44 results on '"Dominique R. T. Appadoo"'
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2. PC 12 Pheochromocytoma Cell Response to Super High Frequency Terahertz Radiation from Synchrotron Source
- Author
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Palalle G. Tharushi Perera, Dominique R. T. Appadoo, Samuel Cheeseman, Jason V. Wandiyanto, Denver Linklater, Chaitali Dekiwadia, Vi Khanh Truong, Mark J. Tobin, Jitraporn Vongsvivut, Olha Bazaka, Kateryna Bazaka, Rodney J. Croft, Russell J. Crawford, and Elena P. Ivanova
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terahertz exposure ,cell viability ,PC 12 neuronal cells ,super high frequency electromagnetic radiation ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
High frequency (HF) electromagnetic fields (EMFs) have been widely used in many wireless communication devices, yet within the terahertz (THz) range, their effects on biological systems are poorly understood. In this study, electromagnetic radiation in the range of 0.3⁻19.5 × 1012 Hz, generated using a synchrotron light source, was used to investigate the response of PC 12 neuron-like pheochromocytoma cells to THz irradiation. The PC 12 cells remained viable and physiologically healthy, as confirmed by a panel of biological assays; however, exposure to THz radiation for 10 min at 25.2 ± 0.4 °C was sufficient to induce a temporary increase in their cell membrane permeability. High-resolution transmission electron microscopy (TEM) confirmed cell membrane permeabilization via visualisation of the translocation of silica nanospheres (d = 23.5 ± 0.2 nm) and their clusters (d = 63 nm) into the PC 12 cells. Analysis of scanning electron microscopy (SEM) micrographs revealed the formation of atypically large (up to 1 µm) blebs on the surface of PC 12 cells when exposed to THz radiation. Long-term analysis showed no substantial differences in metabolic activity between the PC 12 cells exposed to THz radiation and untreated cells; however, a higher population of the THz-treated PC 12 cells responded to the nerve growth factor (NGF) by extending longer neurites (up to 0⁻20 µm) compared to the untreated PC12 cells (up to 20 µm). These findings present implications for the development of nanoparticle-mediated drug delivery and gene therapy strategies since THz irradiation can promote nanoparticle uptake by cells without causing apoptosis, necrosis or physiological damage, as well as provide a deeper fundamental insight into the biological effects of environmental exposure of cells to electromagnetic radiation of super high frequencies.
- Published
- 2019
- Full Text
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3. Vibrational mode analysis of hydrogen-bonded organic frameworks (HOFs): synchrotron infrared studies
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Courtney Ennis, Dominique R. T. Appadoo, Stephanie A. Boer, and Nicholas G. White
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General Physics and Astronomy ,Physical and Theoretical Chemistry - Abstract
Hydrogen-bonded organic frameworks (HOFs) are a promising class of porous crystalline materials for gas sorption and gas separation technologies that can be constructed under mild synthetic conditions. In forming three-dimensional networks of flexible hydrogen bonds between donor/acceptor subunits, these materials have displayed high stability at elevated temperature and under vacuum. Although the structural properties of HOFs are commonly characterized by diffraction techniques, new complimentary methods to elucidate phase behaviour and host-guest interactions at the molecular level are sought, particularly those that can be applied under changing physical conditions or solvent environment. To this end, this study has applied synchrotron far-IR and mid-IR spectroscopy to probe the properties of two known and one new HOF system assembled from tetrahedral amidinium and carboxylate building blocks. All three frameworks produce feature-rich and resolved infrared profiles from 30 to 4000 cm
- Published
- 2022
4. Water Sorption Controls Extreme Single‐Crystal‐to‐Single‐Crystal Molecular Reorganization in Hydrogen Bonded Organic Frameworks
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Stephanie A. Boer, Luke Conte, Andrew Tarzia, Michael T. Huxley, Michael G. Gardiner, Dominique R. T. Appadoo, Courtney Ennis, Christian J. Doonan, Christopher Richardson, and Nicholas G. White
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Organic Chemistry ,General Chemistry ,Catalysis - Abstract
As hydrogen bonded frameworks are held together by relatively weak interactions, they often form several different frameworks under slightly different synthesis conditions and respond dynamically to stimuli such as heat and vacuum. However, these dynamic restructuring processes are often poorly understood. In this work, three isoreticular hydrogen bonded organic frameworks assembled through charge-assisted amidinium⋅⋅⋅carboxylate hydrogen bonds (1
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- 2022
5. THz/Far infrared synchrotron observations of superlattice frequencies in MgB2
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Mahboobeh Shahbazi, Dominique R. T. Appadoo, Ian D.R. Mackinnon, Jose A. Alarco, and Bharati Gupta
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Superconductivity ,Materials science ,Condensed matter physics ,Phonon ,Superlattice ,General Physics and Astronomy ,Synchrotron ,law.invention ,Far infrared ,law ,Condensed Matter::Superconductivity ,Wavenumber ,Density functional theory ,Physical and Theoretical Chemistry ,Absorption (electromagnetic radiation) - Abstract
THz/Far Infrared synchrotron absorption experiments on pure and doped MgB2 samples show that the absorption spectral weight at low wavenumber (i.e.
- Published
- 2021
6. Traditional salt-in-water electrolyte vs. water-in-salt electrolyte with binary metal oxide for symmetric supercapacitors: capacitive vs. faradaic
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Manickam Minakshi Sundaram and Dominique R. T. Appadoo
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Supercapacitor ,Aqueous solution ,Materials science ,Oxide ,chemistry.chemical_element ,Electrolyte ,Electrochemistry ,Energy storage ,Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Electrode ,Lithium - Abstract
The electrochemical energy storage of lithium and sodium ions from aqueous solutions in binary metal oxides is of great interest for renewable energy storage applications. Binary metal oxides are of interest for aqueous energy storage due to their better structural stability and electronic conductivity and tunability of redox potentials. They have also been widely studied as novel electrodes for supercapacitors. The interactions between water and lithium/sodium ions, and water and binary metal oxide surface determine the electrochemical reactions and their long-term stability. Our results indicate that the aqueous sodium electrolyte has a stronger influence on the capacitance and cycling stability of the binary (Ca and Mo) metal oxide electrode than its lithium cousin. The symmetric cell in a two-electrode configuration was assembled with the proposed binary metal oxide, which shows an average discharge voltage of 1.2 V, delivering a specific capacitance of 72 F g−1 at a specific energy density of 32 W h kg−1 based on the total mass of the active materials. The development of highly concentrated aqueous electrolytes such as the “water-in-salt” electrolyte showed a larger electrochemical (voltage) window with enhanced storage capacitance for increasing the salt concentrations has also been discussed.
- Published
- 2020
7. Mechanochemically Synthesised Flexible Electrodes Based on Bimetallic Metal–Organic Framework Glasses for the Oxygen Evolution Reaction
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Zhonghua Zhu, Zhiliang Wang, Jingwei Hou, Jeffrey Harmer, Sebastian Beyer, Wupeng Wang, Dominique R. T. Appadoo, Andraž Krajnc, Ana Guilherme Buzanich, Lianzhou Wang, Vicki Chen, Simon Smart, Linzhou Zhuang, Zhiheng Li, Rijia Lin, Gregor Mali, Thomas D. Bennett, Xuemei Li, and Mengran Li
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chemistry.chemical_classification ,Materials science ,010405 organic chemistry ,Oxygen evolution ,chemistry.chemical_element ,General Medicine ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Catalysis ,0104 chemical sciences ,Coordination complex ,chemistry.chemical_compound ,Chemical engineering ,chemistry ,Mechanochemistry ,Imidazolate ,Metal-organic framework ,Bimetallic strip ,Cobalt ,Zeolitic imidazolate framework - Abstract
The melting behaviour of metal-organic frameworks (MOFs) has aroused significant research interest in the areas of materials science, condensed matter physics and chemical engineering. This work first introduces a novel method to fabricate a bimetallic MOF glass, through melt-quenching of the cobalt-based zeolitic imidazolate framework (ZIF) [ZIF-62(Co)] with an adsorbed ferric coordination complex. The high-temperature chemically reactive ZIF-62(Co) liquid facilitates the formation of coordinative bonds between Fe and imidazolate ligands, incorporating Fe nodes into the framework after quenching. The resultant Co-Fe bimetallic MOF glass therefore shows a significantly enhanced oxygen evolution reaction performance. The novel bimetallic MOF glass, when combined with the facile and scalable mechanochemical synthesis technique for both discrete powders and surface coatings on flexible substrates, enables significant opportunities for catalytic device assembly.
- Published
- 2021
8. Liquid-phase sintering of lead halide perovskites and metal-organic framework glasses
- Author
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Tong Wei, Sean M. Collins, Mingyuan Lu, Anthony K. Cheetham, Luiz H. G. Tizei, Mark S’ Ari, Tiesheng Wang, Dominique R. T. Appadoo, Isaac Martens, Gregor Mali, Lianzhou Wang, Peng Chen, Ebinazar B. Namdas, Zhiliang Wang, Atul Shukla, Rana Doasa, Shih-Chun Lo, Rijia Lin, Thomas D. Bennett, Xuemei Li, Tobias U. Schülli, Vicki Chen, Shichun Li, Andraž Krajnc, Jingwei Hou, Duncan N. Johnstone, and Bun Chan
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Multidisciplinary ,Photoluminescence ,Semiconductor ,Materials science ,Chemical engineering ,Passivation ,business.industry ,Phase (matter) ,Sintering ,Halide ,Metal-organic framework ,business ,Perovskite (structure) - Abstract
Lead halide perovskite (LHP) semiconductors show exceptional optoelectronic properties. Barriers for their applications, however, lie in their polymorphism, instability to polar solvents, phase segregation, and susceptibility to the leaching of lead ions. We report a family of scalable composites fabricated through liquid-phase sintering of LHPs and metal-organic framework glasses. The glass acts as a matrix for LHPs, effectively stabilizing nonequilibrium perovskite phases through interfacial interactions. These interactions also passivate LHP surface defects and impart bright, narrow-band photoluminescence with a wide gamut for creating white light-emitting diodes (LEDs). The processable composites show high stability against immersion in water and organic solvents as well as exposure to heat, light, air, and ambient humidity. These properties, together with their lead self-sequestration capability, can enable breakthrough applications for LHPs.
- Published
- 2021
9. Estimating the dielectric parameters of water and gel using reflectance and transmission at 1.85 to 2.07 THz
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Alireza Lajevardipour, Saulius Juodkazis, Andrew Wood, Negin Foroughimehr, Zoltan Vilagosh, and Dominique R. T. Appadoo
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Materials science ,Optics ,Transmission (telecommunications) ,Terahertz radiation ,business.industry ,business ,Reflectivity - Published
- 2021
10. Attenuated Total Reflection at THz Wavelengths: Peculiarities of Total Internal Reflection and Polariscopy
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Soon Hock Ng, Meguya Ryu, Dominique R. T. Appadoo, Jingwen Hu, Zoltan Vilagosh, Vijayakumar Anand, Junko Morikawa, Andrew Wood, Saulius Juodkazis, Tomas Katkus, and Stefan Lundgaard
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Wavelength ,Total internal reflection ,Materials science ,Optics ,Terahertz radiation ,business.industry ,Attenuated total reflection ,Synchrotron radiation ,Computer Science::Programming Languages ,Physics::Optics ,business ,acoustics - Abstract
Capabilities of the Attenuated Total Reflection (ATR) at THz wavelengths for increased sub-surface depth characterisation of (bio-)materials is presented. The penetration depth of a THz evanescent wave in biological samples is dependent on the wavelength and temperature and can reach 0.1-0.5 mm depth due to strong refractive index change ∼0.4 of the ice-water transition; this is quite significant and important when studying biological samples. Technical challenges are discussed when using ATR for uneven, heterogeneous, high refractive index samples with possibility of frustrated total internal reflection (a breakdown of the ATR reflection-mode into transmission-mode). Local field enhancements at the interface are discussed with numerical/analytical examples. Maxwell’s scaling was used to model behaviour of absorber-scatterer inside materials at the interface with ATR prism for realistic complex refractive indices of bio-materials. Modality of ATR with polarisation analysis is proposed and its principle illustrated, opening an invitation for its experimental validation. The sensitivity of the polarised ATR mode to the refractive index between the sample and ATR prism is revealed. Design principles of polarisation active optical elements and spectral filters are outlined. The results and concepts are based on experiments carried out at the THz beamline of the Australian Synchrotron.
- Published
- 2021
11. Spectroscopy of excised skin patches exposed to THz and far-IR radiation
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Zoltan Vilagosh, Jeffrey A. Davis, Alireza Lajevardipour, Dominique R. T. Appadoo, Saulius Juodkazis, and Andrew Wood
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Absorbance ,Materials science ,Far infrared ,Attenuation coefficient ,Bound water ,Human skin ,Fourier transform infrared spectroscopy ,Photochemistry ,Spectroscopy ,Absorption (electromagnetic radiation) ,Atomic and Molecular Physics, and Optics ,Article ,Biotechnology - Abstract
Applications of far infrared (Far-IR) and terahertz (THz) radiation in areas such as healthcare and security are fast-growing. As a consequence, humans and the environment are becoming more exposed to mm-wave and Far-IR radiation than previously. We examined typical skin-care and sunscreen ingredients and propitiatory products with transmission FTIR, ATR-FTIR and THz-time domain spectroscopy (THz-TDS) methods using fresh and dehydrated toad and fresh human skin samples for their absorption properties in these frequency ranges. The skin hydration compounds glycerol and sorbitol have comparable absorption characteristics to physiological bulk water. Products containing these and similar hydrating compounds have significant Far-IR absorption characteristics. The sunscreen ingredients ZnO (20 micron), TiO2 (mesh 325), and graphene platelet demonstrate a generally poor Far-IR absorbance, with TiO2 displaying some frequency-specific absorption in the 3-6 THz and 12 THz regions. The Far-IR absorbance of proprietary sunscreens was, however, shown not to be significant. The absorption properties of melanin, collagen, bound water, and other constituents are significant in dehydrated skin samples but are not of the same order of importance as the hydrating agents examined.
- Published
- 2021
12. Using Attenuated Total Reflection (ATR) Apparatus to Investigate the Temperature Dependent Dielectric Properties of Water, Ice, and Tissue-Representative Fats
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Andrew Wood, Dominique R. T. Appadoo, Zoltan Vilagosh, Alireza Lajevardipour, and Saulius Juodkazis
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Materials science ,Terahertz radiation ,Analytical chemistry ,Synchrotron radiation ,02 engineering and technology ,Dielectric ,lcsh:Technology ,01 natural sciences ,lcsh:Chemistry ,010309 optics ,0103 physical sciences ,Thermal ,General Materials Science ,Sample preparation ,lcsh:QH301-705.5 ,Instrumentation ,Water content ,Fluid Flow and Transfer Processes ,synchrotron radiation ,lcsh:T ,Process Chemistry and Technology ,allergology ,General Engineering ,021001 nanoscience & nanotechnology ,lcsh:QC1-999 ,Computer Science Applications ,ATR ,temperature variation ,lcsh:Biology (General) ,lcsh:QD1-999 ,lcsh:TA1-2040 ,Attenuated total reflection ,THz ,biological tissues ,lcsh:Engineering (General). Civil engineering (General) ,0210 nano-technology ,Refractive index ,lcsh:Physics - Abstract
A novel method of investigating the temperature dependent variation of aspects of the complex refractive index n* in samples in the THz range using continuous, non-polarised, synchrotron radiation is presented. The method relies on the use of ATR apparatus, and retains the advantage of minimal sample preparation, which is a feature of ATR techniques. The method demonstrates a “proof of concept” of monitoring temperature reflectance whilst continuously heating or cooling samples by using a temperature variable Thermal Sample Stage. The method remains useful when the refractive index of the sample precludes attenuated total reflection study. This is demonstrated with the water reflectance experiments. The temperature dependent ATR reflectance of tissue-representative fats (lard and Lurpak® butter) was investigated with the novel approach. Both are within the ATR range of the diamond crystal in a “true” ATR mode. Lard showed no clear temperature variation between −15 °C and 24 °C at 0.7 to 1.15 THz or 1.70 to 2.25 THz. Lard can be regarded as having invariable, constant, dielectric properties within mixtures when biological substances are being assessed for temperature dependent dielectric variation within the stated THz ranges. Lurpak® butter (water content 14.7%) displayed temperature dependent reflected signal intensity features with a steady decline in reflectivity with increasing temperature. This is in line with the temperature-dependent behaviour of liquid water. There is no rapid change in reflected signal intensity even at −20 °C, suggesting that emulsified water retains liquid-water-like THz properties at freezing temperatures.
- Published
- 2021
13. Terahertz Radiation Stimulates Neurite Growth in PC12 Derived Neurons During Development Phase: Preliminary Study
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Stuart I. Hodgetts, Sergii Romanenko, Dominique R. T. Appadoo, Vincent P. Wallace, Nicholas B. Lawler, and Alan R. Harvey
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Tubulin ,Materials science ,biology ,Neurite ,Terahertz radiation ,Cell culture ,Microtubule ,Cell growth ,biology.protein ,Biophysics ,macromolecular substances ,Elongation ,Cytoskeleton - Abstract
Recently, it was demonstrated that Terahertz (THz) radiation facilitates elongation of tubulin microtubules and actin microfilaments. The phenomenon could have a dramatic impact on living cells, especially in the phase of cell development when dramatic structural changes in cytoskeleton occur. In this study, the THz/Far-IR Beamline of Australian Synchrotron was used as a broadband source of THz radiation to stimulate perturbation in cytoskeleton structure in neuronal culture. Preliminary results indicate alterations of neurite shape and length in THz exposed cell cultures.
- Published
- 2020
14. Halogenated Metal-Organic Framework Glasses and Liquids
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Dean S. Keeble, Alice M. Bumstead, Aoife McCaul, Thomas D. Bennett, Bun Chan, Gregor Mali, Philip A. Chater, Dominique R. T. Appadoo, Vicki Chen, Jingwei Hou, Zeyu Deng, David A. Keen, Rijia Lin, Adam F. Sapnik, María Laura Ríos Gómez, Shichun Li, and Andraž Krajnc
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Steric effects ,Terahertz radiation ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Catalysis ,0104 chemical sciences ,Crystal ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,chemistry ,Imidazolate ,Physical chemistry ,Metal-organic framework ,Deformation (engineering) ,Zeolitic imidazolate framework - Abstract
The synthesis of four novel crystalline zeolitic imidazolate framework (ZIF) structures using a mixed-ligand approach is reported. The inclusion of both imidazolate and halogenated benzimidazolate-derived linkers leads to glass-forming behavior by all four structures. Melting temperatures are observed to depend on both electronic and steric effects. Solid-state NMR and terahertz (THz)/far-IR demonstrate the presence of a Zn-F bond for fluorinated ZIF glasses. In situ THz/far-IR spectroscopic techniques reveal the dynamic structural properties of crystal, glass, and liquid phases of the halogenated ZIFs, linking the melting behavior of ZIFs to the propensity of the ZnN4 tetrahedra to undergo thermally induced deformation. The inclusion of halogenated ligands within metal-organic framework (MOF) glasses improves their gas-uptake properties.
- Published
- 2020
15. Binary-Phase Acetonitrile and Water Aerosols: Infrared Studies and Theoretical Simulation at Titan Atmosphere Conditions
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Mahmut Ruzi, Rebecca Auchettl, Evan G. Robertson, Dominique R. T. Appadoo, and Courtney Ennis
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Atmospheric Science ,Materials science ,010504 meteorology & atmospheric sciences ,Infrared ,Hydrogen bond ,Infrared spectroscopy ,Discrete dipole approximation ,01 natural sciences ,Molecular physics ,Spectral line ,chemistry.chemical_compound ,chemistry ,13. Climate action ,Space and Planetary Science ,Geochemistry and Petrology ,0103 physical sciences ,Astrophysics::Earth and Planetary Astrophysics ,Atmosphere of Titan ,Australian Synchrotron ,Acetonitrile ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,0105 earth and related environmental sciences - Abstract
Acetonitrile (CH3CN) and water (H2O) ice particles were generated within a collisional cooling cell coupled to the Australian Synchrotron light source. The evolution of the aerosols was tracked by infrared spectroscopy compiled over the 4000–50 cm–1 region. Gas pressure and temperature conditions were varied to replicate the lower altitudes of the Titan atmosphere allowing for comparison to far-infrared features detected by the Cassini–Huygens spacecraft. The experimental spectra show that CH3CN and H2O particles are microheterogeneous in composition and spherical in shape. CH3CN lattice bands display temperature-dependent shifts in frequency, implying that pure β-phase is present in the mixed particles. In addition, a red shift identified for the C≡N fundamental stretching mode indicates dipole–dipole and π-electron side-directed hydrogen bond coupling between segregated CH3CN and H2O phases exclusively at the grain interface. Discrete dipole approximation theory was implemented to evaluate various clust...
- Published
- 2018
16. High-resolution far-infrared synchrotron FTIR spectrum of the ν12 band of formamide-d1 (DCONH2)
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Donald McNaughton, Dominique R. T. Appadoo, L.L. Ng, Q.Y. Wu, and T.L. Tan
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Physics ,010304 chemical physics ,Spectrometer ,Infrared ,Rotational–vibrational spectroscopy ,010402 general chemistry ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Synchrotron ,0104 chemical sciences ,law.invention ,symbols.namesake ,Fourier transform ,Far infrared ,law ,0103 physical sciences ,symbols ,Physical and Theoretical Chemistry ,Fourier transform infrared spectroscopy ,Atomic physics ,Ground state ,Spectroscopy - Abstract
The spectrum of the ν 12 band of formamide-d1 (DCONH2) was recorded using a synchrotron Fourier transform infrared (FTIR) spectrometer coupled to the Australian Synchrotron THz/Far-IR beamline, with an unapodized resolution of 0.00096 cm−1 in the 350–210 cm−1 region. For the first time, rovibrational constants up to five quartic and two sextic terms were derived for the v 12 = 1 state through the fitting of a total of 2072 far-infrared transitions using Watson's A-reduced Hamiltonian in the Ir representation with a root-mean-square (rms) deviation of 0.000073 cm−1. The band centre of the ν 12 band of DCONH2 was found to be 289.3327553(47) cm−1 although the experimental uncertainty was limited to ±0.0002 cm−1. Ground state rovibrational constants of DCONH2 up to five quartic and two sextic constants were derived from a fit of 847 ground state combination differences (GSCDs) obtained from the infrared transitions of the ν 12 band, together with 6 previously reported microwave transitions, with a rms deviation of 0.000108 cm−1. The ground state rotational constants (A, B, and C) of DCONH2 were improved while the ground state centrifugal distortion constants were accurately obtained for the first time. The uncertainty of the measured infrared lines was estimated to be ±0.0002 cm−1. From the ground state rotational constants, the inertial defect of DCONH2 was calculated to be 0.0169412(11) uA2.
- Published
- 2018
17. Dominance of eclipsed ferrocene conformer in solutions revealed by the IR spectra between 400 and 500 cm-1
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Stephen P. Best, Feng Wang, Narges Mohammadi, Dominique R. T. Appadoo, and Christopher T. Chantler
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Radiation ,010308 nuclear & particles physics ,Infrared spectroscopy ,01 natural sciences ,Spectral line ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Ferrocene ,chemistry ,0103 physical sciences ,Physical chemistry ,Density functional theory ,Fourier transform infrared spectroscopy ,Solvent effects ,Spectroscopy ,Conformational isomerism - Abstract
A combined Fourier transform infrared (FTIR) spectra of ferrocene (Fc) and density functional theory (DFT) based quantum mechanical calculations confirmed the dominance of the eclipsed Fc conformer in the fingerprint region of 400–500 cm−1 in solutions. Solution IR spectra of Fc measured in acetonitrile (ACN, e = 35.69), dichloromethane (DCM, e = 8.93), tetrahydrofuran (THF, e = 7.43) and dioxane (DOX, e = 2.21) show two well-defined bands in the 480-500 cm−1 region with the higher-wavenumber band higher in intensity. The band profile agrees well with the earlier IR spectra of Lippincott and Nelson (1958) in tetrachloromethane solution as well as more recent measurement in dichloromethane solution of Duhovic and Diaconescu (2013). DFT based quantum mechanical calculations predict that the eclipsed (D5h) Fc conformer is lower in energy than the staggered (D5d) conformer and that the room-temperature solution spectrum of Fc is dominated by that of the D5h form (Best et al., 2016). The present study confirms that solvent effects enhanced the dominance of the D5h Fc conformer which resulted in switch of the IR profile patterns in 400–500 cm−1, from low-wavenumber band higher in intensity pattern in gas phase to higher-wavenumber band higher in intensity in solutions. It further suggests that the effects of solvents on the IR spectra of Fc in this region are small and the solvent model effects are also small for the IR spectrum in the region of 400–500 cm−1 of Fc.
- Published
- 2021
18. The ν 8 band of C 2 HD 3 by high-resolution synchrotron FTIR spectroscopy: Coriolis interactions between the v 8 = 1 and v 6 = 1 states
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Luqman Akasyah, Donald McNaughton, Andy Wong, T.L. Tan, Dominique R. T. Appadoo, and L.L. Ng
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Physics ,010304 chemical physics ,Infrared ,Anharmonicity ,Rotational–vibrational spectroscopy ,010402 general chemistry ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,symbols.namesake ,Nuclear magnetic resonance ,Fourier transform ,Quartic function ,0103 physical sciences ,symbols ,Physical and Theoretical Chemistry ,Fourier transform infrared spectroscopy ,Atomic physics ,Ground state ,Spectroscopy ,Basis set - Abstract
The synchrotron Fourier transform infrared (FTIR) spectrum of the ν 8 band of ethylene- d 3 (C 2 HD 3 ) was measured at an unapodized resolution of 0.00096 cm −1 from 830 to 1010 cm −1 . Rovibrational constants up to five quartic terms were derived with improved precision for the v 8 = 1 state through the fitting of 1566 unperturbed infrared transitions using the Watson's A -reduced Hamiltonian in the I r representation with a root-mean-square (rms) deviation of 0.00044 cm −1 . For the first time, 446 perturbed IR transitions of the ν 8 band were fitted together with the 1566 unperturbed infrared transitions to obtain the a - and b -Coriolis resonance parameters from its interaction with the v 6 = 1 state, with an rms deviation of 0.00039 cm −1 . The IR lines of the ν 6 band were too weak for detection. Three rotational constants, a quartic constant and band center of the v 6 = 1 state were also derived for the first time in this work. Ground state rovibrational constants of C 2 HD 3 up to five quartic constants were also derived from a fit of 906 ground state combination differences with an rms deviation of 0.00030 cm −1 from infrared transitions of the present analysis. The ground state rotational constants are in close agreement with theoretically calculated values using the cc-pVTZ basis set at CCSD(T), MP2 and B3LYP levels of theory. Alpha constants determined from the rotational constants of the v 8 = 1 state derived from the perturbed IR fit compared favourably with those from anharmonic calculations.
- Published
- 2017
19. Torsion–vibration interactions determined from (far) infrared spectra
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Jason R. Gascooke, Dominique R. T. Appadoo, and Warren D. Lawrance
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Materials science ,Absorption spectroscopy ,General Physics and Astronomy ,Infrared spectroscopy ,Torsion (mechanics) ,Molecular physics ,Spectral line ,chemistry.chemical_compound ,Far infrared ,chemistry ,Physics::Chemical Physics ,Physical and Theoretical Chemistry ,Spectroscopy ,Laser-induced fluorescence ,Methyl group - Abstract
Observations of the torsional and low-lying vibrational–torsional states of toluene, p-fluorotoluene, and m-fluorotoluene using the technique of two dimensional laser induced fluorescence (2D-LIF) have revealed interactions between the methyl torsion and low frequency out-of-plane methyl wagging vibration. These interactions can change the values of constants extracted from the analysis of rotational spectra, which usually assume that the large amplitude torsional motion can be treated independent of the small amplitude vibrations. Since out-of-plane methyl wagging modes will be present whenever a methyl group is attached to a planar frame, this type of torsion–vibration interaction is potentially widespread; it is thus important to establish the extent and strength of this type of interaction. 2D-LIF is limited to molecules that fluoresce from excited electronic states, and to explore interactions between torsion and methyl wagging vibrations in a wide range of molecules necessitates developing alternative experimental approaches. Infrared absorption spectroscopy is one such approach. It is shown that for the low torsional barrier case, the torsional sequence bands accompanying the out-of-plane methyl wagging transition provide a sensitive probe of the interaction. As an illustration, the far infrared absorption spectrum of toluene in the region of the M20 band (∼205 cm−1) is presented and analyzed. The torsional sequence structure provides insight into the higher torsional states (up to m = 7) in the ground vibrational state and M20. An analysis of these bands enables the torsion–vibration coupling and torsional constants to be extracted. A general method to analyze such spectra is presented.
- Published
- 2021
20. Attenuated Total Reflection at THz Wavelengths: Prospective Use of Total Internal Reflection and Polariscopy
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Dominique R. T. Appadoo, Soon Hock Ng, Meguya Ryu, Zoltan Vilagosh, Junko Morikawa, Tomas Katkus, Stefan Lundgaard, Vijayakumar Anand, Jingwen Hu, Andrew Wood, and Saulius Juodkazis
- Subjects
Technology ,Materials science ,QH301-705.5 ,Terahertz radiation ,QC1-999 ,Physics::Optics ,four polarisation method ,02 engineering and technology ,01 natural sciences ,010309 optics ,Optics ,0103 physical sciences ,diagnostics ,General Materials Science ,Biology (General) ,Penetration depth ,QD1-999 ,Instrumentation ,Fluid Flow and Transfer Processes ,Total internal reflection ,synchrotron radiation ,business.industry ,Physics ,Process Chemistry and Technology ,General Engineering ,Engineering (General). Civil engineering (General) ,021001 nanoscience & nanotechnology ,Computer Science Applications ,Chemistry ,Wavelength ,ATR ,Attenuated total reflection ,polariscopy ,Reflection (physics) ,THz ,Prism ,TA1-2040 ,0210 nano-technology ,business ,Refractive index - Abstract
Capabilities of the attenuated total reflection (ATR) at THz wavelengths for increased sub-surface depth characterisation of (bio-)materials are presented. The penetration depth of a THz evanescent wave in biological samples is dependent on the wavelength and temperature and can reach 0.1–0.5 mm depth, due to the strong refractive index change ∼0.4 of the ice-water transition; this is quite significant and important when studying biological samples. Technical challenges are discussed when using ATR for uneven, heterogeneous, high refractive index samples with the possibility of frustrated total internal reflection (a breakdown of the ATR reflection mode into transmission mode). Local field enhancements at the interface are discussed with numerical/analytical examples. Maxwell’s scaling is used to model the behaviour of absorber–scatterer inside the materials at the interface with the ATR prism for realistic complex refractive indices of bio-materials. The modality of ATR with a polarisation analysis is proposed, and its principle is illustrated, opening an invitation for its experimental validation. The sensitivity of the polarised ATR mode to the refractive index between the sample and ATR prism is numerically modelled and experimentally verified for background (air) spectra. The design principles of polarisation active optical elements and spectral filters are outlined. The results and proposed concepts are based on experimental conditions at the THz beamline of the Australian Synchrotron.
- Published
- 2021
21. Time-Domain THz Spectroscopy Reveals Coupled Protein–Hydration Dielectric Response in Solutions of Native and Fibrils of Human Lysozyme
- Author
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Saeideh Ostovar Pour, Jeffrey A. Davis, Ashkan Roozbeh, Dominique R. T. Appadoo, Jonathan O. Tollerud, Fabio Novelli, and Ewan W. Blanch
- Subjects
Time Factors ,Materials science ,Terahertz radiation ,Analytical chemistry ,FOS: Physical sciences ,Dielectric ,010402 general chemistry ,01 natural sciences ,Phase (matter) ,0103 physical sciences ,Materials Chemistry ,Water environment ,Humans ,Physics - Biological Physics ,Physical and Theoretical Chemistry ,Terahertz time-domain spectroscopy ,Terahertz Spectroscopy ,010304 chemical physics ,Water ,0104 chemical sciences ,Surfaces, Coatings and Films ,Terahertz spectroscopy and technology ,Solutions ,Dipole ,Amplitude ,Biological Physics (physics.bio-ph) ,Chemical physics ,Muramidase - Abstract
Here we reveal details of the interaction between human lysozyme proteins, both native and fibrils, and their water environment by intense terahertz time domain spectroscopy. With the aid of a rigorous dielectric model, we determine the amplitude and phase of the oscillating dipole induced by the THz field in the volume containing the protein and its hydration water. At low concentrations, the amplitude of this induced dipolar response decreases with increasing concentration. Beyond a certain threshold, marking the onset of the interactions between the extended hydration shells, the amplitude remains fixed but the phase of the induced dipolar response, which is initially in phase with the applied THz field, begins to change. The changes observed in the THz response reveal protein-protein interactions me-diated by extended hydration layers, which may control fibril formation and may have an important role in chemical recognition phenomena.
- Published
- 2017
22. Methods and methodology for FTIR spectral correction of channel spectra and uncertainty, applied to ferrocene
- Author
-
Stephen P. Best, Christopher T. Chantler, Dominique R. T. Appadoo, M. T. Islam, and Ryan M. Trevorah
- Subjects
010401 analytical chemistry ,Analytical chemistry ,Infrared spectroscopy ,010402 general chemistry ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Spectral line ,0104 chemical sciences ,Analytical Chemistry ,chemistry.chemical_compound ,Interference (communication) ,Ferrocene ,chemistry ,Fourier transform infrared spectroscopy ,Australian Synchrotron ,Spectroscopy ,Dispersion (chemistry) ,Instrumentation - Abstract
We present methodology for the first FTIR measurements of ferrocene using dilute wax solutions for dispersion and to preserve non-crystallinity; a new method for removal of channel spectra interference for high quality data; and a consistent approach for the robust estimation of a defined uncertainty for advanced structural χr2 analysis and mathematical hypothesis testing. While some of these issues have been investigated previously, the combination of novel approaches gives markedly improved results. Methods for addressing these in the presence of a modest signal and how to quantify the quality of the data irrespective of preprocessing for subsequent hypothesis testing are applied to the FTIR spectra of Ferrocene (Fc) and deuterated ferrocene (dFc, Fc-d10) collected at the THz/Far-IR beam-line of the Australian Synchrotron at operating temperatures of 7K through 353K.
- Published
- 2017
23. Improved rovibrational constants for the v7= 1 state of ethylene-cis-1,2-d2 (cis-C2H2D2) by high-resolution synchrotron FTIR spectroscopy
- Author
-
G. Aruchunan, Donald McNaughton, Andy Wong, L.L. Ng, M.G. Gabona, Dominique R. T. Appadoo, and T.L. Tan
- Subjects
Physics ,010304 chemical physics ,010504 meteorology & atmospheric sciences ,Infrared ,Analytical chemistry ,Rotational–vibrational spectroscopy ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Synchrotron ,law.invention ,symbols.namesake ,Nuclear magnetic resonance ,law ,0103 physical sciences ,symbols ,Physical and Theoretical Chemistry ,Fourier transform infrared spectroscopy ,Australian Synchrotron ,Ground state ,Hamiltonian (quantum mechanics) ,Spectroscopy ,Microwave ,0105 earth and related environmental sciences - Abstract
Using the far-infrared beamline of the Australian Synchrotron, the spectrum of the ν 7 band of ethylene- cis -1,2- d 2 ( cis -C 2 H 2 D 2 ) was recorded in the 640–990 cm −1 region at an unapodized resolution of 0.00096 cm −1 . A rovibrational analysis of a total of 2823 infrared transitions of the ν 7 band was carried out using an asymmetric rotor fitting program based on the Watson’s A -reduced Hamiltonian in the I r representation to derive up to four sextic constants with a rms deviation of 0.00035 cm −1 . From the fitting of 2634 ground state combination differences (GSCDs) of cis -C 2 H 2 D 2 which were derived from the infrared transitions of the ν 7 band of this work, and ν 10 and ν 12 bands of previous studies, together with 22 microwave frequencies, accurate ground state constants of cis -C 2 H 2 D 2 up to four sextic terms were obtained. The rotational constants ( A , B , and C ) of the v 7 = 1 state of cis -C 2 H 2 D 2 were found to agree within 0.5% with the calculated values using B3LYP/cc-pVTZ and MP2/cc-pVTZ levels of theory. From this work, the band center of ν 7 at 842.209489(20) cm −1 and the rovibrational constants of the v 7 = 1 state of cis -C 2 H 2 D 2 were determined with better accuracy than previously reported.
- Published
- 2017
24. Reinterpretation of Dynamic Vibrational Spectroscopy to Determine the Molecular Structure and Dynamics of Ferrocene
- Author
-
Shawkat Islam, Christopher T. Chantler, Feng Wang, M. Tauhidul Islam, Stephen P. Best, Ryan M. Trevorah, and Dominique R. T. Appadoo
- Subjects
010405 organic chemistry ,Norbornadiene ,Organic Chemistry ,Infrared spectroscopy ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Catalysis ,Transition state ,0104 chemical sciences ,Reaction coordinate ,Molecular dynamics ,chemistry.chemical_compound ,chemistry ,Computational chemistry ,Ab initio quantum chemistry methods ,Molecular vibration ,Physical chemistry ,Conformational isomerism - Abstract
Molecular distortion of dynamic molecules gives a clear signature in the vibrational spectra, which can be modeled to give estimates of the energy barrier and the sensitivity of the frequencies of the vibrational modes to the reaction coordinate. The reaction coordinate method (RCM) utilizes ab initio-calculated spectra of the molecule in its ground and transition states together with their relative energies to predict the temperature dependence of the vibrational spectra. DFT-calculated spectra of the eclipsed (D5h ) and staggered (D5d ) forms of ferrocene (Fc), and its deuterated analogue, within RCM explain the IR spectra of Fc in gas (350 K), solution (300 K), solid solution (7-300 K), and solid (7-300 K) states. In each case the D5h rotamer is lowest in energy but with the barrier to interconversion between rotamers higher for solution-phase samples (ca. 6 kJ mol-1 ) than for the gas-phase species (1-3 kJ mol-1 ). The generality of the approach is demonstrated with application to tricarbonyl(η4 -norbornadiene)iron(0), Fe(NBD)(CO)3 . The temperature-dependent coalescence of the ν(CO) bands of Fe(NBD)(CO)3 is well explained by the RCM without recourse to NMR-like rapid exchange. The RCM establishes a clear link between the calculated ground and transition states of dynamic molecules and the temperature-dependence of their vibrational spectra.
- Published
- 2016
25. The Coriolis-interacting ν6 and ν4 bands of ethylene-cis-1,2-d2 (cis-C2H2D2) by high-resolution synchrotron Fourier transform infrared (FTIR) spectroscopy
- Author
-
T.L. Tan, Donald McNaughton, Dominique R. T. Appadoo, Andy Wong, and M.G. Gabona
- Subjects
Ethylene ,010504 meteorology & atmospheric sciences ,Infrared ,02 engineering and technology ,01 natural sciences ,law.invention ,chemistry.chemical_compound ,symbols.namesake ,Nuclear magnetic resonance ,law ,Physical and Theoretical Chemistry ,Fourier transform infrared spectroscopy ,Australian Synchrotron ,Spectroscopy ,0105 earth and related environmental sciences ,Physics ,Rotational–vibrational spectroscopy ,021001 nanoscience & nanotechnology ,Atomic and Molecular Physics, and Optics ,Synchrotron ,Fourier transform ,chemistry ,symbols ,Atomic physics ,0210 nano-technology ,Hamiltonian (quantum mechanics) - Abstract
The infrared spectrum of the ν 6 band of ethylene- cis -1,2- d 2 ( cis -C 2 H 2 D 2 ) was recorded at the Australian Synchrotron in the 980–1100 cm −1 region at an unapodized resolution of 0.00096 cm −1 . Some of the transitions of the ν 6 band centered at 1039.768335(30) cm −1 were perturbed by the upper energy levels of the infrared inactive ν 4 band at 980.364(24) cm −1 by an a -type Coriolis interaction. Rovibrational analysis of a total of 941 unperturbed and perturbed infrared transitions of the ν 6 band was carried out using an asymmetric rotor fitting program based on the Watson’s A -reduced Hamiltonian in the I r representation to derive up to 2 sextic constants for the ν 6 = 1 state and 3 rotational constants ( A , B , and C ) for the ν 4 = 1 state with a rms deviation of 0.00028 cm −1 . From the perturbed analysis, the a -type Coriolis resonance parameter Z 6 , 4 a for the ν 6 and ν 4 interacting bands was determined to be 0.5249(14) cm −1 . The band center and the rotational constants of the ν 6 = 1 state were found to agree within 1% to the calculated values using B3LYP/cc-pVTZ and MP2/cc-pVTZ levels of theory. Furthermore, the a -type Coriolis coupling constant of these two bands derived from this work were compared to those experimentally determined previously and presently calculated.
- Published
- 2016
26. Focal Plane Array Infrared Imaging of Linear Polymeric Patterns
- Author
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Reo Honda, Jitraporn Vongsvivut, Soon Hock Ng, Masayuki Moritake, Mark J. Tobin, Meguya Ryu, Dominique R. T. Appadoo, Jingliang Li, Armandas Balčytis, Saulius Juodkazis, Junko Morikawa, and Vygantas Mizeikis
- Subjects
Optics ,Materials science ,Cardinal point ,Thermal source ,nanotechnology ,Infrared ,business.industry ,Synchrotron radiation ,Hyperspectral imaging ,Infrared spectroscopy ,business - Abstract
A focal plane array (FPA) detector was used for hyperspectral imaging in the infrared (IR) spectral region using thermal and synchrotron light sources. FPA Fourier-transform IR (FTIR) imaging microspectroscopy will be able to monitor real time changes at specific absorption bands when combined with high brightness synchrotron source. In this study, several types of samples with unique structural motifs were selected and used for assessing the capability of the FPA-FTIR imaging technique. It was shown that the time required for polariscopy at IR wavelengths can be substantially reduced by the FPA-FTIR imaging approach. By using natural and laser fabricated polymers with sub-wavelength features, alignment of absorbing molecular dipoles was revealed as well as higher order patterns (laser fabricated structures). Micro-spectroscopy of absorber orientation reveals alignment patterns even when they are not spatially resolved.
- Published
- 2019
27. PC 12 Pheochromocytoma Cell Response to Super High Frequency Terahertz Radiation from Synchrotron Source
- Author
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Russell J. Crawford, Rodney J. Croft, Palalle G. Tharushi Perera, Jason V. Wandiyanto, Kateryna Bazaka, Denver P. Linklater, Dominique R. T. Appadoo, Vi Khanh Truong, Chaitali Dekiwadia, Olha Bazaka, Elena P. Ivanova, Samuel Cheeseman, Mark J. Tobin, and Jitraporn Vongsvivut
- Subjects
0301 basic medicine ,Cancer Research ,Materials science ,Terahertz radiation ,Scanning electron microscope ,Population ,02 engineering and technology ,Radiation ,lcsh:RC254-282 ,Article ,Cell membrane ,03 medical and health sciences ,medicine ,Irradiation ,education ,cell viability ,education.field_of_study ,Environmental exposure ,021001 nanoscience & nanotechnology ,lcsh:Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,PC 12 neuronal cells ,terahertz exposure ,super high frequency electromagnetic radiation ,030104 developmental biology ,medicine.anatomical_structure ,Oncology ,Transmission electron microscopy ,Biophysics ,0210 nano-technology - Abstract
High frequency (HF) electromagnetic fields (EMFs) have been widely used in many wireless communication devices, yet within the terahertz (THz) range, their effects on biological systems are poorly understood. In this study, electromagnetic radiation in the range of 0.3&ndash, 19.5 ×, 1012 Hz, generated using a synchrotron light source, was used to investigate the response of PC 12 neuron-like pheochromocytoma cells to THz irradiation. The PC 12 cells remained viable and physiologically healthy, as confirmed by a panel of biological assays, however, exposure to THz radiation for 10 min at 25.2 ±, 0.4 °, C was sufficient to induce a temporary increase in their cell membrane permeability. High-resolution transmission electron microscopy (TEM) confirmed cell membrane permeabilization via visualisation of the translocation of silica nanospheres (d = 23.5 ±, 0.2 nm) and their clusters (d = 63 nm) into the PC 12 cells. Analysis of scanning electron microscopy (SEM) micrographs revealed the formation of atypically large (up to 1 µ, m) blebs on the surface of PC 12 cells when exposed to THz radiation. Long-term analysis showed no substantial differences in metabolic activity between the PC 12 cells exposed to THz radiation and untreated cells, however, a higher population of the THz-treated PC 12 cells responded to the nerve growth factor (NGF) by extending longer neurites (up to 0&ndash, 20 µ, m) compared to the untreated PC12 cells (up to 20 µ, m). These findings present implications for the development of nanoparticle-mediated drug delivery and gene therapy strategies since THz irradiation can promote nanoparticle uptake by cells without causing apoptosis, necrosis or physiological damage, as well as provide a deeper fundamental insight into the biological effects of environmental exposure of cells to electromagnetic radiation of super high frequencies.
- Published
- 2019
28. Influence of DFT Functionals and Solvation Models on the Prediction of Far-Infrared Spectra of Pt-Based Anticancer Drugs: Why Do Different Complexes Require Different Levels of Theory?
- Author
-
Ekaterina I. Izgorodina, Bayden R. Wood, Eunice S. H. Gwee, Zoe L. Seeger, and Dominique R. T. Appadoo
- Subjects
010304 chemical physics ,Chemistry ,General Chemical Engineering ,Solvation ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Spectral line ,Article ,0104 chemical sciences ,Ion ,lcsh:Chemistry ,lcsh:QD1-999 ,Computational chemistry ,0103 physical sciences ,Atom ,Molecule ,Density functional theory ,Basis set ,CHELPG - Abstract
Computational modeling was applied to far-infrared (FIR) spectra of Pt-based anticancer drugs to study the hydrolysis of these important molecules. Here, we present a study that investigates the influence of different factors-basis sets on non-Pt atoms, relativistic effective core potentials (RECPs) on the Pt atom, density functional theory (DFT) functionals, and solvation models-on the prediction of FIR spectra of two Pt-based anticancer drugs, cisplatin and carboplatin. Geometry optimizations and frequency calculations were performed with a range of functionals (PBE, PBE0, M06-L, and M06-2X), Dunning's correlation-consisted basis sets (VDZ, VTZ, aVDZ, and aVTZ), RECPs (VDZ-pp, VTZ-pp, aVDZ-pp, and aVTZ-pp), and solvation models (IEFPCM, CPCM, and SMD). The best combination of the basis set/DFT functional/solvation model was identified for each anticancer drug by comparing with experimentally available FIR spectra. Different combinations were established for cisplatin and carboplatin, which was rationalized by means of the partial atomic charge scheme, ChelpG, that was utilized to study the charge transfer between the Pt ion and ligands in both cisplatin and carboplatin.
- Published
- 2018
29. Characterisation of Biological Materials at THz Frequencies by Attenuated Total Reflection: Lard
- Author
-
Saulius Juodkazis, Zoltan Vilagosh, Alireza Lajevardipour, Soon Hock Ng, Dominique R. T. Appadoo, and Andrew Wood
- Subjects
Materials science ,Terahertz radiation ,02 engineering and technology ,lcsh:Technology ,lcsh:Chemistry ,03 medical and health sciences ,0302 clinical medicine ,Optics ,Dispersion (optics) ,General Materials Science ,Penetration depth ,lcsh:QH301-705.5 ,Instrumentation ,Fluid Flow and Transfer Processes ,Total internal reflection ,synchrotron radiation ,lcsh:T ,business.industry ,Process Chemistry and Technology ,General Engineering ,021001 nanoscience & nanotechnology ,lcsh:QC1-999 ,Computer Science Applications ,Wavelength ,ATR ,lcsh:Biology (General) ,lcsh:QD1-999 ,lard ,lcsh:TA1-2040 ,030220 oncology & carcinogenesis ,Attenuated total reflection ,Reflection (physics) ,THz ,lcsh:Engineering (General). Civil engineering (General) ,0210 nano-technology ,business ,Refractive index ,lcsh:Physics - Abstract
The penetration depth of an evanescent wave in Attenuated Total Reflection (ATR) is dependent on the wavelength of the radiation utilised. At THz frequencies, the penetration depth into biological tissues is in the order of 0.1 to 0.5 mm, rendered pig lard was used as a model sample in this study. A method for the direct measurement of the evanescent wave penetration depth is presented which allows for the estimation of the dispersion of the complex refractive index by using the reflection of the evanescent wave from varying sample depths. The method employs frustrated total internal reflection, and has been demonstrated by using the THz/Far-IR beamline at the Australian synchrotron, and modelled using finite difference time domain (FDTD) simulations.
- Published
- 2020
30. High-resolution synchrotron FTIR spectroscopic analysis of the Coriolis interaction between the v10 = 1 and v8 = 1 states of ethylene-cis-1,2-d2
- Author
-
Dominique R. T. Appadoo, T.L. Tan, Andy Wong, Donald McNaughton, and L.L. Ng
- Subjects
010304 chemical physics ,010504 meteorology & atmospheric sciences ,Chemistry ,Infrared ,Biophysics ,Analytical chemistry ,Rotational–vibrational spectroscopy ,Condensed Matter Physics ,01 natural sciences ,Synchrotron ,law.invention ,symbols.namesake ,Full width at half maximum ,Fourier transform ,law ,0103 physical sciences ,symbols ,Physical and Theoretical Chemistry ,Fourier transform infrared spectroscopy ,Atomic physics ,Hamiltonian (quantum mechanics) ,Ground state ,Molecular Biology ,0105 earth and related environmental sciences - Abstract
The synchrotron Fourier transform infrared (FTIR) spectrum of the b-type ν10 band of ethylene-cis-1,2-d2 (cis-C2H2D2) was recorded at a resolution of 0.00096 cm−1 in the 550–750 cm−1 region. The measured FWHM of the lines was about 0.002 cm−1. The ν10 band, centred at 662.871885(27) cm−1 was found to be perturbed through a b-type Coriolis resonance with the infrared inactive ν8 at 759.9582(20) cm−1. In this work, 1989 infrared transitions of ν10 were assigned for the first time. These perturbed and unperturbed infrared transitions were fitted with an rms deviation of 0.00033 cm−1 using the Watson's A-reduced Hamiltonian in the Ir representation with three Coriolis terms to derive the rovibrational constants for v10 = 1 and v8 = 1 states. Ground state rovibrational constants up to two sextic terms were also derived from a fit of a total of 2532 ground state combination differences with arms deviation of 0.00030 cm−1 from the infrared transitions of the present analysis and those determined previous...
- Published
- 2016
31. Synchrotron far-infrared spectra for the characterisation of molecular crystals of forensic interest: Amphetamine, methamphetamine, MDA, MDMA and substituted methcathinones
- Author
-
William F. Graf, Dominique R. T. Appadoo, Courtney Ennis, James R. Pearson, and Evan G. Robertson
- Subjects
Materials science ,Hydrochloride ,010401 analytical chemistry ,Analytical chemistry ,Amphetamine Sulfate ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Spectral line ,Synchrotron ,0104 chemical sciences ,law.invention ,Crystal ,chemistry.chemical_compound ,Far infrared ,chemistry ,law ,Molecule ,0210 nano-technology ,Australian Synchrotron ,Spectroscopy - Abstract
This combined laboratory and theoretical investigation focussed on a suite of crystalline phenethylamine-class molecules of forensic interest: amphetamine sulfate, levo- and dextro-methamphetamine hydrochloride, 3,4-methylenedioxy-methamphetamine (MDMA) hydrochloride, 3,4-methylenedioxy-amphetamine (MDA) hydrochloride, and the hydrochloride salts of two substituted (4-fluoro and 4-methyl) methcathinones. Far-infrared (far-IR) spectra across the 30–600 cm−1 wavenumber range were recorded at the Australian Synchrotron light source. Resolved absorption profiles enabled vibrational features to be assigned via comparison to periodic density functional theory (p-DFT) performed at the B3LYP-D3/6-311 G(d) level. The calculations accurately reproduce the experimental spectra (frequencies and peak intensities) for ordered molecular crystal-type samples, such as methamphetamine stereoisomers and two substituted methcathinones. Significant band broadening for amphetamine sulfate was observed, likely due to crystal disorder, while MDMA and MDA showed convolved stretching modes from comparatively impure samples. For all seven molecular crystals investigated, previously unpublished peak assignments and relative band intensities have now been systematically compiled; completing the spectral region that lies between the more thoroughly studied terahertz and mid-IR regions. These results can be incorporated in spectral libraries and databases to enable far-IR statistical analyses to be performed on forensic samples of mixed or impure compounds.
- Published
- 2020
32. Resolution of ferrocene and deuterated ferrocene conformations using dynamic vibrational spectroscopy: Experiment and theory
- Author
-
Feng Wang, Ryan M. Trevorah, Dominique R. T. Appadoo, N.T.T. Tran, and Christopher T. Chantler
- Subjects
010405 organic chemistry ,Chemistry ,Molecular configuration ,Dihedral angle ,010402 general chemistry ,01 natural sciences ,Molecular physics ,Spectral line ,0104 chemical sciences ,Reaction coordinate ,Inorganic Chemistry ,Molecular dynamics ,Molecular vibration ,Materials Chemistry ,Physical and Theoretical Chemistry ,Spectroscopy ,Conformational isomerism - Abstract
The signature of molecular vibrations and distortions in dynamic molecules gives a complex fingerprint which is insightful and can substantiate (or otherwise) chemical hypotheses regarding molecular and conformer stability. Using high-accuracy experimental data of ferrocene (Fc) and deuterated ferrocene (dFc, Fc − d 10 ) at temperatures from 7 K through to 388 K, we obtain complex spectral profiles which require an advanced reaction coordinate model to explain. We obtain compelling evidence that the single conformer model (staggered D 5 d or eclipsed D 5 h ) used to interpret and explain many experimental results on ferrocene is invalid. However we also present compelling evidence that mixed conformer models are invalid, where ferrocene is represented by an effective dihedral angle between the cyclopentadienyl (Cp) rings; or by a mixture of Boltzmann populations of the two conformers. We find no evidence for single or mixed conformer models despite covering almost all conclusions from past literature for gas, solution or solid phase Fc. Some molecular dynamics computations have imputed free rotation at liquid helium temperatures or at room temperature – we find no evidence for either of these hypotheses. We measure and derive point-wise experimental uncertainty of the spectra, enabling quantitative assessment of specific chemical and physical models about the origin of the spectral line-shapes. A new principle based on the reaction coordinate is introduced. Advanced spectroscopy and modelling is introduced for hypothesis testing, to articulate the nature of the potential surface, the reaction coordinate and subtle conformational changes in dilute systems. Two expected spectral peaks appear inverted in the gas phase, but are explained by our Reaction Coordinate Method (RCM) model. The non-uniform broadening of the singlet and doublet peaks with increasing temperature is explained. Our experimental analysis shows that the lowest energy conformer is D 5 h for both Fc and dFc. We are able to represent the reduced mass ratios of the lowest vibrational modes for Fc and dFc of 1.11 for ν 1 for Fc to Fc - d 9 and of 1.10 for Fc to Fc - d 10 . The measured barrier height for rotation is 7.4 kJ mol−1 and 6.3 kJ mol−1 for Fc and dFc respectively, in comparison to numerous theoretical treatments and past experimental studies. For the first time, we obtain agreement of the model with the complex spectral evolution of profiles. These new techniques are sensitive discriminants of alternate models and chemical systems, which argues for wider application to other complex or impenetrable problems across fields arising for numerous other solutions, frozen or at room temperature.
- Published
- 2020
33. 3D Printed Gratings: IR-THz Applications
- Author
-
Edvinas Skliutas, William L. Hart, Dominique R. T. Appadoo, Meguya Ryu, Elena P. Ivanova, Mangirdas Malinauskas, Denver P. Linklater, Saulius Juodkazis, Junko Morikawa, Yaw-Ren Eugene Tan, and Armandas Balčytis
- Subjects
3d printed ,business.industry ,Terahertz radiation ,Optoelectronics ,business - Published
- 2018
34. 3D Printed Polarising Grids for IR-THz Synchrotron Radiation
- Author
-
Elena P. Ivanova, Mangirdas Malinauskas, Denver P. Linklater, Meguya Ryu, Edvinas Skliutas, Saulius Juodkazis, Junko Morikawa, Yaw-Ren Eugene Tan, William L. Hart, Armandas Balčytis, and Dominique R. T. Appadoo
- Subjects
Materials science ,business.industry ,Terahertz radiation ,Linear polarization ,Physics::Optics ,Synchrotron radiation ,02 engineering and technology ,Polarizer ,021001 nanoscience & nanotechnology ,Polarization (waves) ,Dichroic glass ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Synchrotron ,Electronic, Optical and Magnetic Materials ,law.invention ,010309 optics ,Optics ,law ,0103 physical sciences ,0210 nano-technology ,Anisotropy ,business - Abstract
Grid polarisers 3D-printed out of commercial acrilic resin were tested for the polariser function and showed spectral regions where the dichroic ratio and implying importance of molecular and/or stress induced anisotropy. Metal-coated 3D-printed THz optical elements can find a range of applications in intensity and polarization control of IR-THz beams. The used 3D printing method allows for fabrication of an arbitrary high aspect ratio grid polarisers. Polarization analysis of synchrotron THz radiation was carried out with a standard stretched polyethylene polariser and revealed that the linearly polarized (horizontal) component contributes up to 22% ± 5% to the circular polarized synchrotron emission extracted by a gold-coated mirror with a horizontal slit inserted near the bending magnet edge. Comparison with theoretical predictions shows a qualitative match with dominance of the edge radiation.
- Published
- 2018
35. The Limits of Rovibrational Analysis: The Severely Entangled ν1 Polyad Vibration of Dichlorodifluoromethane in the Greenhouse IR Window
- Author
-
Evan G. Robertson, Chris Medcraft, Dominique R. T. Appadoo, and Donald McNaughton
- Subjects
chemistry.chemical_compound ,chemistry ,Infrared ,Infrared window ,Resonance ,Dichlorodifluoromethane ,Rotational–vibrational spectroscopy ,Physical and Theoretical Chemistry ,Atomic physics ,Spectral line ,Line (formation) ,Fermi Gamma-ray Space Telescope - Abstract
Five intense bands of dichlorodifluoromethane (CFC-12, or R12) in the infrared atmospheric window help make it a major greenhouse contributor. These include the ν1 fundamental at 1101.4 cm(-1) and the ν2 + ν3 combination at 1128.6 cm(-1). High-resolution spectra measured using the Australian Synchrotron Far-Infrared beamline were analyzed, and transitions of C(35)Cl2F2 were assigned to ν1, ν2 + ν3, and the ν3 + 2ν5 combination at 1099.7 cm(-1). The (v3 = 1; v5 = 2) state couples indirectly to v1 = 1 via Fermi resonances linking both states with v2 = v3 = 1. The v1 = 1 rotational levels are further riddled with perturbations and avoided crossings due to Coriolis resonance with the upper vibrational states of ν2 + ν9 at 1102.4 cm(-1) and (indirectly) ν2 + ν7 at 1105.8 cm(-1). A global treatment of all these states fits the observed line positions and satisfactorily accounts for the significant intensity of ν2 + ν3. Spectral simulations elucidate resonance perturbations that affect the distribution of IR absorption in the CF stretch region, and consequently the global warming potential of R12. Combination levels derived from rovibrational analysis lead to reassessment of the gas phase wavenumber values for the ν3 (458.6 cm(-1)), ν7 (437.7 cm(-1)) and ν9 (436.9 cm(-1)) fundamentals of C(35)Cl2F2, consistent with a cold, vapor phase far IR spectrum and previously published solid state spectra. B3LYP and MP2 anharmonic frequency calculations provide further support. At the MP2/aug-cc-pVTZ level, the root mean square (r.m.s.) error for unscaled anharmonic fundamentals is 6.2 cm(-1), decreased to 1.7 cm(-1) if only considering the seven lowest wavenumber modes, and integrated band intensities according with experimental literature values. Smaller basis sets produce band strengths that are too high. Low-resolution band assignments are reported for C(35)Cl(37)ClF2, C(37)Cl2F2, and (13)C(35)Cl2F2.
- Published
- 2014
36. Silk: Optical Properties over 12.6 Octaves THz-IR-Visible-UV Range
- Author
-
Xungai Wang, Jeffrey A. Davis, Saulius Juodkazis, Armandas Balčytis, Fabio Novelli, Jingliang Li, Meguya Ryu, Junko Morikawa, Gediminas Seniutinas, Xuewen Wang, Dominique R. T. Appadoo, and Shan Du
- Subjects
spectroscopy ,Materials science ,Wild silk ,Analytical chemistry ,Fibroin ,02 engineering and technology ,Antheraea pernyi ,010402 general chemistry ,01 natural sciences ,Article ,terahertz ,Bombyx mori ,biopolymer ,General Materials Science ,silk ,Composite material ,Spectroscopy ,biology ,solubility ,fibroin ,proteins ,biodegradable polymers ,Spectral bands ,021001 nanoscience & nanotechnology ,biology.organism_classification ,0104 chemical sciences ,Wavelength ,SILK ,0210 nano-technology - Abstract
Domestic (Bombyx mori) and wild (Antheraea pernyi) silk fibers were characterised over a wide spectral range from THz 8 cm −1 ( λ = 1.25 mm, f = 0.24 THz) to deep-UV 50 × 10 3 cm − 1 ( λ = 200 nm, f = 1500 THz) wavelengths or over a 12.6 octave frequency range. Spectral features at β-sheet, α-coil and amorphous fibroin were analysed at different spectral ranges. Single fiber cross sections at mid-IR were used to determine spatial distribution of different silk constituents and revealed an α-coil rich core and more broadly spread β-sheets in natural silk fibers obtained from wild Antheraea pernyi moths. Low energy T-ray bands at 243 and 229 cm −1 were observed in crystalline fibers of domestic and wild silk fibers, respectively, and showed no spectral shift down to 78 K temperature. A distinct 20±4 cm−1 band was observed in the crystalline Antheraea pernyi silk fibers. Systematic analysis and assignment of the observed spectral bands is presented. Water solubility and biodegradability of silk, required for bio-medical and sensor applications, are directly inferred from specific spectral bands.
- Published
- 2017
37. Rovibrational constants of the ground and ν 12 = 1 states of C 2 D 4 by high-resolution synchrotron FTIR spectroscopy
- Author
-
T.L. Tan, M.G. Gabona, Donald McNaughton, Peter D. Godfrey, and Dominique R. T. Appadoo
- Subjects
Physics ,Absorption spectroscopy ,Infrared ,Resolution (electron density) ,Rotational–vibrational spectroscopy ,Atomic and Molecular Physics, and Optics ,symbols.namesake ,Fourier transform ,Nuclear magnetic resonance ,symbols ,Wavenumber ,Physical and Theoretical Chemistry ,Fourier transform infrared spectroscopy ,Atomic physics ,Ground state ,Spectroscopy - Abstract
The Fourier transform infrared (FTIR) absorption spectrum of the ν 12 fundamental band of ethylene- d 4 (C 2 D 4 ) was recorded in the 1000–1150 cm −1 region with a resolution of 0.00096 cm −1 using the THz/far-infrared beamline of the Australian Synchrotron. Upper state ( ν 12 = 1) rovibrational constants consisting of three rotational constants and up to five quartic constants were improved by assigning and fitting 3950 rovibrational transitions using Watson’s A -reduced and S -reduced Hamiltonians in the I r representation. The band centres of the unperturbed A -type ν 12 band are found to be 1076.984958(14) cm −1 and 1076.984813(14) cm −1 for A -reduced and S -reduced Hamiltonians respectively. The present analysis, covering a wider wavenumber range and higher J and K c values (up to 58) than previous studies, yielded upper state constants including the band centre which are more accurate than previously reported. The rms deviation of the upper state ( ν 12 = 1) fit is 0.00040 cm −1 in the A -reduction and 0.00041 cm −1 in the S -reduction. Improved ground state rovibrational constants were also determined from the fit of 3151 ground state combination differences (GSCD) from the presently-assigned transitions of the ν 12 band of C 2 D 4 using Watson’s A -reduced and S -reduced Hamiltonians in the I r representation. The rms deviation of the GSCD fit is 0.00036 cm −1 in the A -reduction and 0.00035 cm −1 in the S -reduction. The ground state constants of C 2 D 4 derived from the experimental GSCD fit are in good agreement with those from theoretical calculations using the B3LYP/cc-pVTZ, MP2/cc-pVTZ, and CSSD/cc-pVTZ levels, up to five quartic constants.
- Published
- 2014
38. High-resolution Fourier transform infrared spectrum of the ν6 band of formamide-d (DCONH2)
- Author
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Dominique R. T. Appadoo, L.L. Ng, Q.Y. Wu, and T.L. Tan
- Subjects
Physics ,010304 chemical physics ,Infrared ,Anharmonicity ,Rotational–vibrational spectroscopy ,010402 general chemistry ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Rotational energy ,symbols.namesake ,Fourier transform ,0103 physical sciences ,symbols ,Isotopologue ,Rotational spectroscopy ,Physical and Theoretical Chemistry ,Atomic physics ,Ground state ,Spectroscopy - Abstract
The high-resolution rovibrational spectrum of the ν 6 band of formamide-d1 (DCONH2) was recorded using the Fourier transform infrared (FTIR) spectrometer at the Australian Synchrotron with an unapodized resolution of 0.00142 cm−1 in the mid-infrared region of 910–990 cm−1 region. From the rovibrational analysis of this A-type band, the v 6 = 1 state rovibrational constants up to one sextic term were derived for the first time from a total of 1450 infrared transitions. These transitions were fitted using the Watson's A-reduced Hamiltonian in the Ir representation with a root-mean-square (rms) deviation of 0.00078 cm−1. The center of the ν 6 band of DCONH2 was accurately determined to be 954.857070(41) cm−1. This v 6 = 1 state was found to be perturbed by the nearby ( v 10 = 1 , v 12 = 1) state, just around 16 cm−1 higher. Two c-Coriolis parameters were obtained from the perturbation analysis of the interaction between the rotational energy levels of the v 6 = 1 and ( v 10 = 1 , v 12 = 1) states. Additionally, the center of the ν 10 + ν 12 band was found at 970.671(41) cm−1 and rotational constant C was fitted accurately. Ground state rotational constants and centrifugal distortion constants up to two sextic terms were obtained by fitting of 1432 ground state combination differences (GSCDs) derived from the infrared (IR) transitions of both the ν 6 band of the present work and ν 12 band of previous work of DCONH2, together with 6 previously reported microwave frequencies. The root-mean-square (rms) deviation value of this fit was 0.000183 cm−1. The ground state constants in this study provide a better representation for the DCONH2 isotopologue as the values were derived from a larger pool of GSCDs. In addition, ground state rovibrational constants up to five quartic terms and rotational constants of the v 6 = 1 state were computed from theoretical anharmonic calculations at two different levels of theory, B3LYP and MP2 with the cc-pVTZ basis set, for comparison with the experimental results.
- Published
- 2019
39. Infrared Polariscopy Imaging of Linear Polymeric Patterns with a Focal Plane Array
- Author
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Meguya Ryu, Jingliang Li, Masayuki Moritake, Jitraporn Vongsvivut, Junko Morikawa, Reo Honda, Dominique R. T. Appadoo, Mark J. Tobin, Saulius Juodkazis, Vygantas Mizeikis, Armandas Balčytis, and Soon Hock Ng
- Subjects
Brightness ,Materials science ,focal plane array ,hyperspectral imaging ,Infrared ,General Chemical Engineering ,Synchrotron radiation ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Article ,thermal source ,law.invention ,lcsh:Chemistry ,Optics ,law ,silk ,General Materials Science ,infrared spectroscopy ,Absorption (electromagnetic radiation) ,synchrotron radiation ,business.industry ,Hyperspectral imaging ,021001 nanoscience & nanotechnology ,Laser ,Synchrotron ,0104 chemical sciences ,Cardinal point ,lcsh:QD1-999 ,0210 nano-technology ,business - Abstract
Polariscopy is demonstrated using hyperspectral imaging with a focal plane array (FPA) detector in the infrared (IR) spectral region under illumination by thermal and synchrotron light sources. FPA Fourier-transform IR (FTIR) imaging microspectroscopy is useful for monitoring real time changes at specific absorption bands when combined with a high brightness synchrotron source. In this study, several types of samples with unique structural motifs were selected and used for assessing the capability of polariscopy under this FPA-FTIR imaging technique. It was shown that the time required for polariscopy at IR wavelengths can be substantially reduced by the FPA-FTIR imaging approach. By using natural and laser fabricated polymers with sub-wavelength features, alignment of absorbing molecular dipoles and higher order patterns (laser fabricated structures) were revealed. Spectral polariscopy at the absorption peaks can reveal the orientation of sub-wavelength patterns (even when they are not spatially resolved) or the orientation of the absorbing dipoles.
- Published
- 2019
40. Comprehensive vibrational spectroscopic investigation of trans,trans,trans-[Pt(N3)2(OH)2(py)2], a Pt(IV) diazido anticancer prodrug candidate
- Author
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Leone Spiccia, Manja Kubeil, Bayden R. Wood, Tanmaya Joshi, Ekaterina I. Izgorodina, Robbin R. Vernooij, Evyenia Shaili, Bimbil Graham, Dominique R. T. Appadoo, and Peter J. Sadler
- Subjects
Organoplatinum Compounds ,Infrared ,Stereochemistry ,Antineoplastic Agents ,010402 general chemistry ,01 natural sciences ,Article ,Inorganic Chemistry ,RC0254 ,chemistry.chemical_compound ,symbols.namesake ,Pyridine ,Prodrugs ,Physical and Theoretical Chemistry ,010405 organic chemistry ,Ligand ,Spectrum Analysis ,3. Good health ,0104 chemical sciences ,Crystallography ,chemistry ,13. Climate action ,Molecular vibration ,Attenuated total reflection ,symbols ,Density functional theory ,Azide ,Raman spectroscopy - Abstract
We report a detailed study of a promising photoactivatable metal-based anticancer prodrug candidate, trans,trans,trans-[Pt(N3)2(OH)2(py)2] (C1; py = pyridine), using vibrational spectroscopic techniques. Attenuated total reflection Fourier transform infrared (ATR-FTIR), Raman, and synchrotron radiation far-IR (SR-FIR) spectroscopies were applied to obtain highly resolved ligand and Pt-ligand vibrations for C1 and its precursors (trans-[Pt(N3)2(py)2] (C2) and trans-[PtCl2(py)2] (C3)). Distinct IR- and Raman-active vibrational modes were assigned with the aid of density functional theory calculations, and trends in the frequency shifts as a function of changing Pt coordination environment were determined and detailed for the first time. The data provide the ligand and Pt-ligand (azide, hydroxide, pyridine) vibrational signatures for C1 in the mid- and far-IR region, which will provide a basis for the better understanding of the interaction of C1 with biomolecules., A detailed investigation of the Pt(IV) diazido anticancer prodrug candidate, trans,trans,trans-[Pt(N3)2(OH)2(py)2], and its precursors is presented, which includes the use of synchrotron radiation far-IR, ATR-FTIR, Raman, and DFT calculations.
- Published
- 2016
41. Heavy snow: IR spectroscopy of isotope mixed crystalline water ice
- Author
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Donald McNaughton, Evan G. Robertson, Dominique R. T. Appadoo, Liang Shi, Andy Wong, and Rebecca Auchettl
- Subjects
010304 chemical physics ,Hydrogen ,Hydride ,Chemistry ,Buffer gas ,Intermolecular force ,Analytical chemistry ,General Physics and Astronomy ,chemistry.chemical_element ,Infrared spectroscopy ,010402 general chemistry ,01 natural sciences ,Potential energy ,Spectral line ,0104 chemical sciences ,0103 physical sciences ,Fermi resonance ,Physics::Chemical Physics ,Physical and Theoretical Chemistry - Abstract
Mid-infrared spectra have been measured for crystalline water ice aerosols of widely varied H/D isotopic composition. Particles with diameters ranging from 10–200 nm were generated via rapid collisional cooling with a cold buffer gas over a range of temperatures from 7–200 K. In near isotopically pure ices, the νL band position is slightly red-shifted with increasing temperature whilst in the ν2 region apparently anomalous shifts in peak maxima are explained by the contribution of a broad 2νL band of H2O and a 3νL band of D2O together with ν2 intensity that is particularly weak in low temperature crystalline ice. The hydrogen bonded OH (or OD) oscillator bands of near pure H2O (or D2O) ices are blue-shifted with temperature, with a gradient very similar to that of the corresponding band in isotope diluted samples, HOD in D2O (or H2O). It implies that this observed temperature trend is predominantly due to the intrinsic change in local hydride stretch potential energy, rather than to changes in intermolecular coupling. However, it is also observed that the narrow hydride stretch bands of an isotope diluted sample rapidly develop sub-band structure as the oscillator concentration increases, evidence of strong intermolecular coupling and a high degree of delocalisation. Anomalous blue-shifts in the OD stretch profile as D2O concentration grows is attributable to Fermi resonance with 2ν2 of D2O, in much closer proximity than the corresponding H2O levels. Theoretical results from a mixed quantum/classical approach are used to validate these findings in the hydride stretching region. Theory qualitatively reproduces the experimental trends as a function of temperature and isotopic variance.
- Published
- 2016
42. HYDROGEN AND NITROGEN BROADENED ETHANE AND PROPANE ABSORPTION CROSS SECTIONS
- Author
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Peter F. Bernath, Dominique R. T. Appadoo, Robert J. Hargreaves, and Brant Billinghurst
- Subjects
chemistry.chemical_compound ,Materials science ,Hydrogen ,chemistry ,Propane ,chemistry.chemical_element ,Photochemistry ,Absorption (electromagnetic radiation) ,Nitrogen - Published
- 2015
43. Back Cover: Reinterpretation of Dynamic Vibrational Spectroscopy to Determine the Molecular Structure and Dynamics of Ferrocene (Chem. Eur. J. 50/2016)
- Author
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Feng Wang, Ryan M. Trevorah, Dominique R. T. Appadoo, Shawkat Islam, M. Tauhidul Islam, Stephen P. Best, and Christopher T. Chantler
- Subjects
chemistry.chemical_compound ,Molecular dynamics ,Ferrocene ,chemistry ,Ab initio quantum chemistry methods ,Computational chemistry ,Organic Chemistry ,Infrared spectroscopy ,Molecule ,Cover (algebra) ,General Chemistry ,Catalysis - Published
- 2016
44. Double-layered nitrocellulose membrane sample holding technique for THz and FIR spectroscopic measurements
- Author
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Bernd Fischer, Gretel M. Png, Dominique R. T. Appadoo, Derek Abbott, and Ruth Plathe
- Subjects
Materials science ,Terahertz radiation ,business.industry ,Scattering ,Atomic and Molecular Physics, and Optics ,Synchrotron ,law.invention ,Terahertz spectroscopy and technology ,Optics ,law ,Attenuation coefficient ,Absorption (electromagnetic radiation) ,Spectroscopy ,business ,Fabry–Pérot interferometer - Abstract
In terahertz (THz) and far-infrared (FIR) spectroscopic measurements, weak absorption spectral features due to small quantities of test sample can be masked by undesirable etalon fringe artifacts caused by multiple reflections within a pellet or a rigid sample holder. A double-layered nitrocellulose (NC) membrane structure is proposed in this paper as an alternative holder for small quantities of either dry or wet pure (no added polyethylene powder) samples with significantly reduced etalon artifacts. Utilizing a THz time-domain spectroscopy system and a synchrotron source, we demonstrate the performance of the NC structure across the THz/FIR spectrum, benchmarking against pellets holding similarly small quantities of α-lactose powder either with or without different grades of polyethylene powder. With only pure samples to consider, scattering can be mitigated effectively in NC-derived spectra to reduce their baselines.
- Published
- 2015
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