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The relationships between the polymerization related to structure and the composition of different types of natural resins were determined. Analyses were carried out by Fourier transform infrared spectroscopy (FTIR), differential thermal analysis–thermogravimetry (DTA-TG) and hot stage microscopy (HSM). Copal specimens were collected from the Mai-Ndombe Lake, Democratic Republic of Congo, and amber pieces that came from Bitterfeld, Germany, and from Kaliningrad, Russia. FTIR spectra of copal show a vibrational band at 1643 cm−1 (C=O stretching) attributed to communic acids, while amber shows a band at 1735 cm−1 associated with ester-group vibrations and a shoulder at about 3340 cm−1, suggesting partial oxidization. DTA shows the main exothermic peak, related to the combustion, at 546–552 °C in amber and at 518 °C in copal. The derivative thermogravimetry (DTG) peaks vary in the different resin types; in amber, they occur at 333–335, 401–404 and 548–555 °C and are related to mass losses of 31, 26 and 39 mass%, respectively; copal peaks are at 394 and 507 °C, with mass losses of 71 and 27 mass%, respectively. In copal, hot stage microscopy (HSM) shows the start of sintering at 131 °C, followed by an expansion produced by the material decomposition and the generation of gases that cannot be released because of the material plastic behaviour. Finally, the increase in pressure produces an explosion that results in a lower viscosity of the liquid, which at this point can no longer support the internal pressure of gases. In amber samples, a smaller decrease in viscosity is observed and the start of sintering occurs at 150 °C with no significant change in their morphology. [ABSTRACT FROM AUTHOR]

Herbs have been used as natural remedies for disease treatment, prevention, and health care. Some herbs with functional properties are also used as food or food additives for culinary purposes. The quality and safety inspection of herbs are influenced by various factors, which need to be assessed in each operation across the whole process of herb production. Traditional analysis methods are time-consuming and laborious, without quick response, which limits industry development and digital detection. Considering the efficiency and accuracy, faster, cheaper, and more environment-friendly techniques are highly needed to complement or replace the conventional chemical analysis methods. Infrared (IR) and Raman spectroscopy techniques have been applied to the quality control and safety inspection of herbs during the last several decades. In this paper, we generalize the current application using IR and Raman spectroscopy techniques across the whole process, from raw materials to patent herbal products. The challenges and remarks were proposed in the end, which serve as references for improving herb detection based on IR and Raman spectroscopy techniques. Meanwhile, make a path to driving intelligence and automation of herb products factories. [ABSTRACT FROM AUTHOR]

Natural waters contain some carbonaceous materials referred to as dissolved organic matter, which is mainly composed of humic acids (HA). Owing to its polydispersed character related to the presence of diverse molecular size fractions (< 450 kDa to even < 1 kDa), HA displays curious reactivity in natural waters and during water treatment train. In this study, a system-based stepwise approach was tracked by characterizing HA following photolysis, adsorptive interactions, and solar photocatalysis using bare TiO2, sol–gel prepared TiO2, and their respective Cu-doped specimens complementary to kinetic evaluation on this respect. For this purpose, prior to and following each treatment, HA was monitored by dissolved organic carbon content, UV–vis parameters, and fluorescence features. Attenuated total reflection Fourier transform infrared (FTIR), surface-enhanced Raman scattering spectroscopy (SERS), XRD, SEM, EDAX XPS, and DRS were used to characterize the materials and solutions reported in this study. Most significant quantitative variations were attained in UV–vis spectroscopic parameters along with fluorescence characteristics; however, infrared and Raman profiles displayed slight deviations in qualitative measures. Differentiation between the selected photocatalyst specimens could be visualized through molecular size effects pointing out the significance of HA 10 kDa fraction. For the first time, this study reports the degradation of specific fractions of HA as a function of their molecular size fraction. Cu-TiO2 seems to photocatalyze more effectively the degradation of the diverse HA fractions due to their more extended absorption of solar light by this photocatalyst. [ABSTRACT FROM AUTHOR]

Water oxidation is an essential reaction of an artificial photosystem for solar fuel generation because it provides electrons needed to reduce carbon dioxide or protons to a fuel. Earth-abundant metal oxides are among the most attractive catalytic materials for this reaction because of their robustness and scalability, but their efficiency poses a challenge. Knowledge of catalytic surface intermediates gained by vibrational spectroscopy under reaction conditions plays a key role in uncovering kinetic bottlenecks and provides a basis for catalyst design improvements. Recent dynamic infrared and Raman studies reveal the molecular identity of transient surface intermediates of water oxidation on metal oxides. Combined with ultrafast infrared observations of how charges are delivered to active sites of the metal oxide catalyst and drive the multielectron reaction, spectroscopic advances are poised to play a key role in accelerating progress toward improved catalysts for artificial photosynthesis.

The two new hybrids single crystals having the general formula [(CH3CH2CH2)4N]2MIICl4 with MII = Co (1) and Mn (2) have been synthetised by the slow evaporation process in aqueous solutions. In this article, these compounds were described by the following characterization techniques: X-rays diffraction, thermal analysis (TGA-TDA), vibrational spectroscopy, nuclear magnetic resonance (NMR), and electrical properties. From the crystallographic study, the crystals (1) and (2) have been disclosed to be crystallized too in the centrosymmetric monoclinic systems, with space group P21/c (Z = 4) and C2/c (Z = 8), respectively. Their crystal structures consist of [MCl4]2− anions and two different cations [(CH3CH2CH2)4N]+, which are connected by a three dimensional network of C-H···Cl hydrogen bonds. In both crystals, each MII center atom being surrounded by four chloride ligands forming a slightly distorted tetrahedral geometry. The tetrahedral [CoCl4]2− is ordered, while the tetrahedral [MnCl4]2− is disordered. Some tetrapropylammonium cations of these compounds are found to be disordered. The thermal analysis studies made in the temperature range (298–473 K) did not show any phase transition for the two crystals. Furthermore, the electrical properties of the two compounds are studied by using the complex impedance spectroscopy technique in the temperature and frequency field varied of 290–363 K and 1 kHz–13 MHz, respectively.

The way to analyze data in spectroscopy has changed substantially. At the same time, data science has evolved to the point where spectroscopy can find space to be housed, adapted and be functional. The integration of the two sciences has introduced a knowledge gap between data scientists who know about advanced machine learning techniques and spectroscopists who have a solid background in chemometrics. To reach a symbiosis, the knowledge gap requires bridging. This review article focuses on introducing data science subjects to non-specialist spectroscopists, or those unfamiliar with the subject. The article will explain concepts that are covered in machine learning, such as supervised learning, unsupervised learning, deep learning, and most importantly, the difference between machine learning and artificial intelligence. This article also includes examples of published spectroscopy research, in which some of the concepts explained here are applied. Machine learning together with spectroscopy can provide a useful, fast, and efficient tool to analyze samples of interest both for industrial and research purposes. [ABSTRACT FROM AUTHOR]

The two new hybrids single crystals having the general formula [(CH 3 CH 2 CH 2) 4 N] 2 MIICl 4 with MII = Co (1) and Mn (2) have been synthetised by the slow evaporation process in aqueous solutions. In this article, these compounds were described by the following characterization techniques: X-rays diffraction, thermal analysis (TGA-TDA), vibrational spectroscopy, nuclear magnetic resonance (NMR), and electrical properties. From the crystallographic study, the crystals (1) and (2) have been disclosed to be crystallized too in the centrosymmetric monoclinic systems, with space group P 2 1 /c (Z = 4) and C 2/c (Z = 8), respectively. Their crystal structures consist of [MCl 4 2− anions and two different cations [(CH 3 CH 2 CH 2) 4 N]+, which are connected by a three dimensional network of C-H···Cl hydrogen bonds. In both crystals, each MII center atom being surrounded by four chloride ligands forming a slightly distorted tetrahedral geometry. The tetrahedral [CoCl 4 2− is ordered, while the tetrahedral [MnCl 4 2− is disordered. Some tetrapropylammonium cations of these compounds are found to be disordered. The thermal analysis studies made in the temperature range (298–473 K) did not show any phase transition for the two crystals. Furthermore, the electrical properties of the two compounds are studied by using the complex impedance spectroscopy technique in the temperature and frequency field varied of 290–363 K and 1 kHz–13 MHz, respectively. [ABSTRACT FROM AUTHOR]

Abstract Metastable Ln -orthophosphates (Ln = Tb, Dy) with monoclinic monazite-type structure were obtained via a precipitation route in aqueous solutions and subsequent thermal treatment. The lattice parameters and fractional coordinates of the atoms in the crystal structures were determined by Rietveld refinement of X-ray diffraction data. The lattice parameters of the metastable monazites obtained here fit well into the linear trends observed for stable Ln PO 4 monazites (Ln = La–Gd). Infrared spectroscopic investigations on TbPO 4 and DyPO 4 with monazite structure confirmed the expected shift of the modes to higher wavenumbers with increasing atomic number and decreasing cation radius. Raman spectra of the metastable Tb- and Dy-monazites were obtained for the first time, revealing a typical monazite spectrum for monoclinic TbPO 4 , continuing the general linear correlation between the Raman shifts and Ln 3+ radii observed for the lighter Ln PO 4 monazites. In contrast, the Raman spectrum of DyPO 4 was severely biased by fluorescence effects. Graphical abstract Structural characterisation of metastable Tb-/Dy-monazites. Image 1 Highlights • Comprehensive structural study on metastable Tb- and Dy-monazites. • First published Raman spectra of monoclinic TbPO 4 and DyPO 4. • Data fit well into linear trends of stable lanthanide phosphates. [ABSTRACT FROM AUTHOR]

We investigated the temperature influence on the structural and vibrational properties of β‐HMX (β‐octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine) by using a combination of ab initio molecular dynamics and density function theory. The results indicate that the lattice constants and unit‐cell volume of HMX do not present obvious temperature effects. Most of the vibrational modes display similar hardening trend under the temperatures, suggesting that the crystal transformation of HMX under heat is through this displacement. The dependence of Infra‐red spectra on the temperature presents red‐shifted and a little decrease in the intensity of lattice vibration. This may suggest that there is a new bond formed or an old bond broken in the system if the temperature is higher than 873 K. The intensity of ratting mode caused by volumetric contraction and Raman are obviously much larger than that of the crystalline HMX at 0 K and the lattice vibrations are blue‐shifted. It demonstrates that the lattice vibrations are much more drastic. It is found that the deformation vibrations of cycle and nitro group are milder at relatively higher temperatures. This suggests that the cycle space becomes small enough to influence the HMX vibrations. [ABSTRACT FROM AUTHOR]

Abstract A new phosphonic acid, (2-oxo-2-(thiophen-2-yl)ethyl) phosphonic acid (OTEPA), was synthesized and its molecular and crystal structures investigated using several experimental techniques complemented by different types of calculations. The experimental techniques used include infrared and Raman spectroscopies and single crystal X-ray crystallography. Calculations were performed at both molecular mechanics and DFT(B3LYP)/6–311++G(d,p) levels of approximation, for the isolated molecule. The conformational space of OTEPA was investigated and the most stable conformers characterized both structurally and spectroscopically. It was found that in the lower energy conformers of OTEPA an intramolecular H-bond exists between one of the OH groups of the phosphonic acid fragment and the carbonyl oxygen atom. The two lowest energy conformers have the sulphur atom of the thiophene ring eclipsed with the carbonyl oxygen atom, allowing for the establishment of an O⋯S stabilizing contact, similar to the N⋯S type contact found previously in other molecular systems. Noteworthy, in the crystalline phase the OTEPA molecules do not assume one of the most stable conformations for the isolated molecule, but exist in a conformation similar to that of high-energy conformers, which have predicted energies relative to the conformational ground state higher than 13 kJ mol−1. The infrared spectra of the monomeric molecules of the compound isolated in a low temperature solid argon matrix and of the crystal of the neat compound were also investigated and assigned, together with the Raman spectrum of the crystalline compound. Graphical abstract Image 1 Highlights • A new phosphonic acid (OTEPA) was synthesized and characterized. • OTEPA's molecular and crystal structures were investigated using several experimental and theoretical methods. • Major intramolecular and intermolecular (in the solid phase) interactions were evaluated. • Vibrational spectra for the isolated molecule (in solid argon) and in the crystalline phase were interpreted. [ABSTRACT FROM AUTHOR]

The Bi4I16·4(C6H9N2) 2(H2O) compound was synthesized by slow evaporation at room temperature. It exhibits a zero-dimensional (0D) tetrameric structure, comprising [Bi4I16]4− distorted octahedra, with strong I⋯I interactions among adjacent anionic clusters. We used Hirshfeld surface analysis to discuss the strength of hydrogen bonds and to quantify the inter-contacts (two-dimensional (2D) fingerprint plots). It revealed that the hydrogen bonding interactions H⋯I (56.3%), π–π stacking (11.7%), and I⋯I interactions (5.9%) play the major role in the stability of the crystal structure. The crystal morphology was simulated using Bravais–Friedel, Donnay–Harker (BFDH) and growth morphology (GM) methods. The experimental habit of the title compound was adequately reproduced by the two models. The calculated results show that the crystal morphology of the title compound in a vacuum is dominated by five facets: (020), (011), (110), (10−1), and (11−1). The (020) facet is the largest among all the facets calculated. Projection of the facet showed that there are a few polar groups on the (020) facet. In the 50–400 and 400–4000 cm−1 frequency regions, we measured the Raman and infrared spectra, respectively, of the title compound, and we assigned the observed vibration modes.

This paper undertakes the synthesis by slow evaporation method at room temperature of a new organic-inorganic hybrid material with the general formula [C12H13N2O]H2AsO4. The newly developed hybrid is characterized by X-ray single crystal diffraction, Infrared, Raman spectroscopy and density functional theory (DFT) calculations. At ambient temperature, this compound crystallizes in the non-centrosymmetric space group P212121 of the orthorhombic system. The structural arrangement is formed by infinite anionic chains extending parallel to the direction [100]. The organic entities are linked to these chains by N-H···O type hydrogen bonds which play an important role in the cohesion of the one-dimensional network. The optimized molecular structure, vibrational spectra and the optical properties were calculated by the DFT method using the B3LYP function with the LanL2DZ basis set. The vibrational wavenumbers were evaluated for this compound by using transferable scale factor. The first hyperpolarizability value βtot of the title compound is equal to 15.94 × 10−31 esu. Hence, the large β value calculated by the B3LYP method shows that the studied compound is a good NLO material and is suitable for future non-linear optical studies. The HOMO-LUMO energy gap and other related molecular properties are going to be discussed and reported later. [ABSTRACT FROM AUTHOR]

Glasses in the 25BaSO 4 − 30B2O 3 − (45 −x)P2O 5 − xDy2O3 system with x = 0.1, 0.3, 0.5, 0.7 and 1.0 mol% have been prepared by the melt quenching approach with the aim of using it for optical and white light application. The structural properties are examined by Fourier transform infrared and Raman spectroscopy. The amorphous state of the glasses matrices is determined by X-ray diffraction. Direct and indirect energy bandgap have been evaluated via the data found from UV–visible–near IR spectroscopy. The spectral absorption, emission and excitation are measured, and it is found that the glass doped Dy2O3 ions display good UV-excited luminescence of 4F 9 / 2 → 6 H 1 5 / 2 and 4F 9 / 2 → 6 H 1 3 / 2 transition around 480–500 and 570–600 nm corresponding to blue and yellow regions respectively. The physical parameters of the glasses have also been calculated. Infrared and Raman of the borosulfophosphate glasses revealed intense spectrum which is characterized by distinct bands. [ABSTRACT FROM AUTHOR]

Water oxidation is an essential reaction of an artificial photosystem for solar fuel generation because it provides electrons needed to reduce carbon dioxide or protons to a fuel. Earth-abundant metal oxides are among the most attractive catalytic materials for this reaction because of their robustness and scalability, but their efficiency poses a challenge. Knowledge of catalytic surface intermediates gained by vibrational spectroscopy under reaction conditions plays a key role in uncovering kinetic bottlenecks and provides a basis for catalyst design improvements. Recent dynamic infrared and Raman studies reveal the molecular identity of transient surface intermediates of water oxidation on metal oxides. Combined with ultrafast infrared observations of how charges are delivered to active sites of the metal oxide catalyst and drive the multielectron reaction, spectroscopic advances are poised to play a key role in accelerating progress toward improved catalysts for artificial photosynthesis. [ABSTRACT FROM AUTHOR]

The new mineral shumwayite (IMA2015-058), [(UO2)(SO4)(H2O)2]2·H2O, was found in the Green Lizard and Giveaway-Simplot mines, White Canyon district, San Juan County, Utah, USA, where it occurs as a secondary alteration phase. At the Green Lizard mine, it is found in association with calcite, gypsum, plášilite, pyrite, rozenite and sulfur; at the Giveaway-Simplot mine, shumwayite is associated with rhomboclase and römerite. The mineral occurs as pale greenish-yellow monoclinic prisms, elongated on [100], up to ~0.3 mm long and commonly in subparallel to random intergrowths. The mineral is transparent with a vitreous lustre and has a white streak. It fluoresces bright greenish white under both longwave and shortwave ultraviolet radiation. The Mohs hardness is ∼2. Crystals are brittle with perfect {011} cleavage and irregular fracture. The mineral is slightly deliquescent and is easily soluble in room temperature H2O. The calculated density is 3.844 g cm-3. Optically, shumwayite is biaxial (+/-), with α = 1.581(1), β = 1.588(1), γ = 1.595(1) (measured in white light). The measured 2Vx based on extinction data collected on a spindle stage is 89.8(8)°; the calculated 2Vx is 89.6°. Dispersion is strong, but the sense is not defined because the optic sign is ambiguous. No pleochroism was observed. The optical orientation is X = b, Y ≈ c, Z ≈ a. Energy-dispersive spectrometer analyses (with H2O based on the crystal structure) yielded the empirical formula U2.01S1.99O12.00·5H2O. Shumwayite is monoclinic, P21/c a = 6.74747(15), b = 12.5026(3), c = 16.9032(12) Å, β = 90.919(6)°, V = 1425.79(11) Å3 and Z = 4. The crystal structure (R1 = 1.88% for 2936 F > 4σF) contains UO7 pentagonal bipyramids and SO4 tetrahedra that link by corner-sharing to form [(UO2)(SO4)(H2O)2] chains along [100]. The chains and isolated H2O groups between them are linked together only by hydrogen bonds. The mineral is named in honour of the Shumway family, whose members account for the discovery and mining of hundreds of uranium deposits on the Colorado Plateau, including the Green Lizard mine. [ABSTRACT FROM AUTHOR]

Single crystals of a new organic–inorganic hybrid compound, with the formula (4-APH)(4-APH 2 )[AsO 4 ]·H 2 O, was synthesized at room temperature by slow evaporation method and characterized by X-ray diffraction at 150 K, DSC–TG measurements, FT-IR and Raman spectroscopies. The title salt, (C 5 H 7 N 2 )(C 5 H 8 N 2 )[AsO 4 ]·H 2 O, contains mono and diprotonated 4-aminopyridine cations, an arsenate trianion and one water molecule. The diprotonated 4-ammoniumpyridinium dication [C 5 H 8 N 2 ] 2+ is disordered over two positions with refined site occupancies of 0.73 and 0.27 however the monoprotonated 4-aminopyridinium cation [C 5 H 7 N 2 ] + is ordered. The 4-aminopyridinium rings are essentially planar and occur in stacks along b axis. In the crystal, the As III atom is coordinated by four O atoms in a slightly distorted tetrahedral geometry. The arsenate O atoms link the 4-aminopyridinium cations and water molecules into a three-dimensional network via intermolecular O–H···O and N–H···O hydrogen bonds. Additionally, in this structure, the different types and the nature of aromatic–aromatic interactions can distinguish between a stacked arrangement are parallel displaced and T-shaped conformation. Furthermore, the room temperature IR and Raman spectra of the title compound were recorded and analyzed. On the basis of detailed vibrational studies, the detailed assignment confirms the presence of the organic groups and the anionic entities. Besides, the thermal analysis studies have been performed, but no phase transition was found in the temperature range 298–625 K. Results from X-ray crystallography, Raman, IR spectroscopy and thermal analysis are combined to provide a description of the new organic arsenate monohydrate, (C 5 H 7 N 2 )(C 5 H 8 N 2 )[AsO 4 ]·H 2 O. [ABSTRACT FROM AUTHOR]

Correlation between theoretical and experimental (infrared and Raman spectroscopies) vibrational spectra of two compounds, both with a silyl group present in their main chain and with an optically active structure (L-valine) as side group, was performed. These compounds are based in a chiral dicarboxylic acid monomer and its respective polyamide-imide, oligomer that was previously synthesized by a direct polycondensation. Spectra were recorded in the region comprised between 500 and 4000 cm−1for infrared and Raman analysis. The Raman spectra were obtained through a 1064 nm laser as excitation source. Theoretical models were carried out in order to find the optimal molecular geometry of the analyzed systems, with a complete assignment of their vibrational spectra. The Raman experimental data obtained with a Nd:YAG laser for this kind of silylated organic compounds, and the comparison between these results with the theoretical data is a useful advance in the polymer synthesis field, which can be used as reference for subsequent studies. [ABSTRACT FROM AUTHOR]

Fragments of land snail (Achatinidae) shell were found at Border Cave in varying proportions in all archaeological members, with the exception of the oldest members 5 WA and 6 BS (>227,000 years ago). They were recovered in relatively high frequencies in Members 4 WA, 4 BS, 1 RGBS and 3 WA. The shell fragments present a range of colours from lustrous beige to brown and matt grey. The colour variability can occur when shell is heated. This possibility was explored here through experimental heating of giant land snail shell fragments (Achatinidae , Metachatina kraussi - brown lipped agate snail) in a muffle furnace from 200 to 550 °C for different lengths of time. Colour change, weight loss, and shattering of the heated samples were recorded. Transformation of aragonite into calcite and the occurrence of organic material was investigated by means of Infrared and Raman spectroscopy. Scanning electron microscopy was also used on selected specimens to help identify heat-induced transformation as opposed to taphonomic alteration. The identification on archaeological fragments of features produced by experimentally heating shells at high temperatures or for long periods has led us, after discarding alternative hypotheses, to conclude that large African land snails were systematically brought to the site by humans, roasted and consumed, starting from 170,000 years ago and, more intensively between 160,000 and 70,000 years ago. Border Cave is at present the earliest known site at which this subsistence strategy is recorded. Previous research has shown that charred whole rhizomes and fragments of edible Hypoxis angustifolia were also brought to Border Cave to be roasted and shared at the site. Thus, evidence from both the rhizomes and snails in Border Cave supports an interpretation of members of the group provisioning others at a home base, which gives us a glimpse into the complex social life of early Homo sapiens. • Experimental heating of giant land snail shell fragments produces heating attributes observed on archaeological shell. • Chemical transformation was identified using Raman and Infrared spectroscopy. • Shell is relatively abundant in occupations dated between 170,000 and 70,000 years ago; uncommon in more recent occupations. • The transport of snails to a home base suggests food sharing among early Homo sapiens. [ABSTRACT FROM AUTHOR]

New approaches for identifying disease resistant trees are needed, as the incidence of diseases caused by non-native and invasive pathogens increases. These approaches must be rapid, reliable, cost-effective, and should have the potential to be adapted for high-throughput screening or phenotyping. Within the context of trees and tree diseases, we summarize vibrational spectroscopic and chemometric methods that have been used to distinguish between groups of trees which vary in disease susceptibility or other important characteristics based on chemical fingerprint data. We also provide specific examples from the literature of where these approaches have been used successfully. Finally, we discuss future application of these approaches for wide-scale screening and phenotyping efforts aimed at identifying disease resistant trees and managing forest diseases.

This paper reviews charge ordering in the organic conductors, β″-(BEDT-TTF) (TCNQ), θ-(BEDT-TTF)2X, and α-(BEDT-TTF)2X. Here, BEDT-TTF and TCNQ represent bis(ethylenedithio)tetrathiafulvalene and 7,7,8,8-tetracyanoquinodimethane, respectively. These compounds, all of which have a quarter-filled band, were evaluated using infrared and Raman spectroscopy in addition to optical conductivity measurements. It was found that β″-(BEDT-TTF)(TCNQ) changes continuously from a uniform metal to a charge-ordered metal with increasing temperature. Although charge disproportionation was clearly observed, long-range charge order is not realized. Among six θ-type salts, four compounds with a narrow band show the metal-insulator transition. However, they maintain a large amplitude of charge order (Δρ~0.6) in both metallic and insulating phases. In the X = CsZn(SCN)4 salt with intermediate bandwidth, the amplitude of charge order is very small (Δρ < 0.07) over the whole temperature range. However, fluctuation of charge order is indicated in the Raman spectrum and optical conductivity. No indication of the fluctuation of charge order is found in the wide band X = I3 salt. In α-(BEDT-TTF)2I3 the amplitude of charge order changes discontinuously from small amplitude at high temperature to large amplitude (Δρmax~0.6) at low temperature. The long-range charge-ordered state shows ferroelectric polarization with fast optical response. The fluctuation of multiple stripes occurs in the high-temperature metallic phase. Among α-(BEDT-TTF)2MHg(SCN)4 (X = NH4, K, Rb, Tl), the fluctuation of charge order is indicated only in the X = NH4 salt. α′-(BEDT-TTF)2IBr2 shows successive phase transitions to the ferroelectric state keeping a large amplitude of charge order (Δρmax~0.8) over the whole temperature range. It was found that the amplitude and fluctuation of charge order in these compounds is enhanced as the kinetic energy (bandwidth) decreases.

Many chemometric tools are invaluable and have proven effective in data mining and substantial dimensionality reduction of highly multivariate data. This becomes vital for interpreting various physicochemical data due to rapid development of advanced analytical techniques, delivering much information in a single measurement run. This concerns especially spectra, which are frequently used as the subject of comparative analysis in e.g. forensic sciences. In the presented study the microtraces collected from the scenarios of hit-and-run accidents were analysed. Plastic containers and automotive plastics (e.g. bumpers, headlamp lenses) were subjected to Fourier transform infrared spectrometry and car paints were analysed using Raman spectroscopy. In the forensic context analytical results must be interpreted and reported according to the standards of the interpretation schemes acknowledged in forensic sciences using the likelihood ratio approach. However, for proper construction of LR models for highly multivariate data, such as spectra, chemometric tools must be employed for substantial data compression. Conversion from classical feature representation to distance representation was proposed for revealing hidden data peculiarities and linear discriminant analysis was further applied for minimising the within-sample variability while maximising the between-sample variability. Both techniques enabled substantial reduction of data dimensionality. Univariate and multivariate likelihood ratio models were proposed for such data. It was shown that the combination of chemometric tools and the likelihood ratio approach is capable of solving the comparison problem of highly multivariate and correlated data after proper extraction of the most relevant features and variance information hidden in the data structure. [ABSTRACT FROM AUTHOR]

The X-ray powder diffraction pattern shows that at room temperature, [N(CH 3 ) 3 H] 2 CuCl 4 is crystallized in the monoclinic system with P2 1 /c space group. The phase transitions at T 1 ≈ 292/298 K, T 2 ≈ 262/264 K and T 3 ≈ 241 Khave been confirmed by the differential scanning calorimetry (DSC). Besides, the different phases have been studied by Raman scattering on single crystals, in the frequency range of 60–350 cm −1 . The infrared and Raman spectra are attributed on the basis of ab initio calculations of the vibrational spectra. The optimized geometries, calculated vibrational frequencies, infrared intensities and Raman activities of [CuCl 4 ] 2− and [N(CH 3 ) 3 H] + were calculated using the Hartree-Fock (HF) and density functional theory (B3LYP) with 3-21G, 6-31G(d) and 6-311G(d,p)basis sets. The temperature evolution of Raman spectra reveals the existence of phase transitions at T 1 , T 2 and T 3 and confirms their nature. [ABSTRACT FROM AUTHOR]

The mineral donnayite-(Y) has been studied by scanning electron microscopy with chemical analysis using EDX and vibrational spectroscopy. Multiple carbonate stretching modes are observed and support the concept of non-equivalent carbonate units in the donnayite-(Y) structure. Intense sharp bands at 464, 479 and 508 cm are assigned to YO stretching modes. Raman bands at 765 and 775 cm are assigned to the CO ν bending modes and Raman bands at 589, 611, 674 and 689 cm are assigned to the CO ν bending modes. Multiple Raman and infrared bands in the OH stretching region are observed, proving the existence of water in different molecular environments in the structure of donnayite-(Y). [ABSTRACT FROM AUTHOR]

New approaches for identifying disease resistant trees are needed as the incidence of diseases caused by non-native and invasive pathogens increases. These approaches must be rapid, reliable, cost-effective, and should have the potential to be adapted for high-throughput screening or phenotyping.Within the context of trees and tree diseases, we summarize vibrational spectroscopic and chemometric methods that have been used to distinguish between groups of trees which vary in disease susceptibility or other important characteristics based on chemical fingerprint data. We also provide specific examples from the literature of where these approaches have been used successfully. Finally, we discuss future application of these approaches for wide-scale screening and phenotyping efforts aimed at identifying disease resistant trees and managing forest diseases. [ABSTRACT FROM AUTHOR]

Herbs have been used as natural remedies for disease treatment, prevention, and health care. Some herbs with functional properties are also used as food or food additives for culinary purposes. The quality and safety inspection of herbs are influenced by various factors, which need to be assessed in each operation across the whole process of herb production. Traditional analysis methods are time-consuming and laborious, without quick response, which limits industry development and digital detection. Considering the efficiency and accuracy, faster, cheaper, and more environment-friendly techniques are highly needed to complement or replace the conventional chemical analysis methods. Infrared (IR) and Raman spectroscopy techniques have been applied to the quality control and safety inspection of herbs during the last several decades. In this paper, we generalize the current application using IR and Raman spectroscopy techniques across the whole process, from raw materials to patent herbal products. The challenges and remarks were proposed in the end, which serve as references for improving herb detection based on IR and Raman spectroscopy techniques. Meanwhile, make a path to driving intelligence and automation of herb products factories., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Chen, Liu, Zhang, Wang, Yang, Zhao, Peng, Kong and Huang.)

The feasibility of using tungsten oxide catalysts for furfuryl alcohol (FA) oligomerization reaction was investigated in the liquid phase at 100 °C and ambient pressure. Five dimers (2,2′-difurylmethane, 2-(2-furylmethyl)-5-methylfuran, difurfuryl ether, 4-furfuryl-2-pentenoic acid γ-lactone, 5-fufuryl-furfuryl alcohol) and two trimers (2,5-difurfurylfuran and 2,2′-(furylmethylene)bis(5-methylfuran)) were observed in GC and GC/MS, while Infrared (IR) and Raman spectroscopy provided the co-existence of conjugated diene and diketone molecular structures, respectively. It was observed that C 9 –C 15 oligomers' selectivity decreased as the reaction time increased. Ether bridge and terminal alcohol are dominant FA dimers which are very similar to sulfuric acid (homogeneous catalysis) catalyzed dehydration/condensation reaction of FA. [ABSTRACT FROM AUTHOR]

The effects of addition of Al 3 + , W 6 + , Nb 5 + and Pb 2 + on the density, thermal, optical properties of borotellurite glasses and on the B–O, Te–O and Al–O speciation are studied. Density maximizes in glasses containing Pb 2 + and minimizes in glasses with Al 3 + . The optical absorption cut-off wavelength increases with the addition of heavy metal ions while Al 3 + shifts it to lower wavelengths. W 6 + , Nb 5 + and Al 3 + strengthen the borotellurite network and enhance the glass transition temperatures, however Pb 2 + decreases it. The glass transition temperature is a linear function of the average single bond energy of the glass network. 11 B Magic Angle Spinning (MAS) Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared studies found that the BO 4 structural units are unstable in the presence of Al 3 + , W 6 + and Nb 5 + , however Pb 2 + has an opposite effect and promotes the formation of BO 4 . 27 Al MAS NMR showed that alumino-borotellurite glasses contain AlO 6 , AlO 5 and AlO 4 structural units whose relative concentrations depend on alumina mol%. Raman spectroscopy was used to determine Te–O coordination in glasses, the later decreased on adding metal ions and Al 3 + produced a maximum suppression of TeO 4 units. [ABSTRACT FROM AUTHOR]

The present paper undertakes the study of a new organic/inorganic hybrid compound [2-CH 3 C 6 H 4 NH 3 ]HSO 4 .H 2 O characterized by the X-ray diffraction, TG-DTA, IR and Raman spectroscopy accomplished with DFT calculation. It is crystallized in the monoclinic system with the centrosymmetric space group P 2 1 /c, with a = 9.445 (5) Å, b = 10.499 Å, c = 10.073 Å, β = 90.627 (5)° and Z = 4. The atomic arrangement can be described as inorganic layers built by infinite chains, parallel to the (a c) planes between which the organic cations are inserted. In this atomic arrangement, hydrogen bonds and π-π interactions between the different species have an important role in the tri-dimensional network cohesion. Besides, the X-ray powder diffraction of the title compound confirms the existence of only one phase at room temperature. The thermal decomposition of precursors studied by thermo gravimetric analysis (TGA), the differential thermal analysis (DTA) and the temperature-dependent X-ray diffraction, show crystalline anhydrous compounds upon dehydration. DFT/BHHLYP calculations were performed, using the DZV (d,p) basis set, to determine the harmonic frequencies of the vibrational modes of an optimized cluster structure. The calculated modes were animated using the Molden graphical package to give tentative assignments of the observed IR and Raman spectra. [ABSTRACT FROM AUTHOR]

In the present article, the molecular structure of S-methyl thiobutanoate, CH 3 CH 2 CH 2 C(O)SCH 3 was determined by ab initio (MP2) and DFT calculations using different basis sets. The infrared and Raman spectra for the liquid phase were also recorded and the bands observed were assigned to the vibrational normal modes. The experimental and calculations confirm the presence of two most stable conformers, one with pseudo anti – syn conformation and another with gauche – syn conformation. The study was completed using natural bond orbital (NBO) and AIM analysis. The molecular properties like dipole moment, molecular electrostatic potential surface (MEP) and HOMO–LUMO molecular orbitals were calculated to get a better insight of the properties of the title molecule. Global and local reactivity descriptors were computed in order to predict reactivity and reactive sites on the molecule for nucleophilic, electrophilic and radical attacks. [ABSTRACT FROM AUTHOR]

The mineral tilleyite-Y, a carbonate-silicate of calcium, has been studied by scanning electron microscopy with chemical analysis using energy dispersive spectroscopy (EDX) and Raman and infrared spectroscopy. Multiple carbonate stretching modes are observed and support the concept of non-equivalent carbonate units in the tilleyite structure. Multiple Raman and infrared bands in the OH stretching region are observed, proving the existence of water in different molecular environments in the structure of tilleyite. Vibrational spectroscopy offers new information on the mineral tilleyite. [ABSTRACT FROM AUTHOR]

The mineral brianyoungite, a carbonate–sulphate of zinc, has been studied by scanning electron microscopy (SEM) with chemical analysis using energy dispersive spectroscopy (EDX) and Raman and infrared spectroscopy. Multiple carbonate stretching modes are observed and support the concept of non-equivalent carbonate units in the brianyoungite structure. Intense Raman band at 1056 cm −1 with shoulder band at 1038 cm −1 is assigned to the CO 3 2 − ν 1 symmetric stretching mode. Two intense Raman bands at 973 and 984 cm −1 are assigned to the symmetric stretching modes of the SO 4 2 − anion. The observation of two bands supports the concept of the non-equivalence of sulphate units in the brianyoungite structure. Raman bands at 704 and 736 cm −1 are assigned to the CO 3 2 − ν 4 bending modes and Raman bands at 507, 528, 609 and 638 cm −1 are assigned to the CO 3 2 − ν 2 bending modes. Multiple Raman and infrared bands in the OH stretching region are observed, proving the existence of water and hydroxyl units in different molecular environments in the structure of brianyoungite. Vibrational spectroscopy enhances our knowledge of the molecular structure of brianyoungite. [ABSTRACT FROM AUTHOR]

The rare-earth metal(III) bromide ortho -oxidotungstates(VI) with the formula RE Br[WO 4 ] crystallize triclinically in space group P 1 ¯ ( a = 689–693, b = 715–728, c = 1074–1107 pm, α = 103–106, β ≈ 108 and γ = 93–95°, Z = 4) for RE = Y, Gd–Yb. Their crystal structure is isotypic with the most examples of the formally analogous lanthanoid(III) bromide oxidomolybdates(VI) RE Br[MoO 4 ] with RE = Y, Pr, Nd, Sm, Gd–Lu. It contains two crystallographically different rare-earth metal(III) cations with coordination numbers of seven plus one for ( RE 1) 3+ and seven for ( RE 2) 3+ . The ( RE 1) 3+ cations are surrounded by three Br – and four plus one O 2− anions forming distorted trigonal dodecahedra, while the ( RE 2) 3+ cations exhibit a coordination environment of one Br – and six O 2− anions in the shape of a monocapped trigonal prism. Furthermore, the structure contains two crystallographically independent, isolated tetrahedral [WO 4 ] 2− units. All these polyhedra are fused together to form 1 ∞ { RE Br[WO 4 ]} chains running along [012]. Since the title compounds, synthesized by solid-state reactions from the underlying binaries, emerge as pure phases according to X-ray powder diffractometry, spectroscopic and magnetic measurements were performed. [ABSTRACT FROM AUTHOR]

We have studied the carbonate mineral kamphaugite-(Y)(CaY(CO 3 ) 2 (OH)·H 2 O), a mineral which contains yttrium and specific rare earth elements. Chemical analysis shows the presence of Ca, Y and C. Back scattering SEM appears to indicate a single pure phase. The vibrational spectroscopy of kamphaugite-(Y) was obtained using a combination of Raman and infrared spectroscopy. Two distinct Raman bands observed at 1078 and 1088 cm −1 provide evidence for the non-equivalence of the carbonate anion in the kamphaugite-(Y) structure. Such a concept is supported by the number of bands assigned to the carbonate antisymmetric stretching mode. Multiple bands in the ν 4 region offers further support for the non-equivalence of carbonate anions in the structure. Vibrational spectroscopy enables aspects of the structure of the mineral kamphaugite-(Y) to be assessed. [ABSTRACT FROM AUTHOR]

We have studied the mineral poldervaartite CaCa[SiO 3 (OH)(OH)] which forms a series with its manganese analogue olmiite CaMn[SiO 3 (OH)](OH) using a range of techniques including scanning electron microscopy, thermogravimetric analysis, Raman and infrared spectroscopy. Chemical analysis shows the mineral is reasonably pure and contains only calcium and manganese with low amounts of Al and F. Thermogravimetric analysis proves the mineral decomposes at 485 °C with a mass loss of 7.6% compared with the theoretical mass loss of 7.7%. A strong Raman band at 852 cm −1 is assigned to the SiO stretching vibration of the SiO 3 (OH) units. Two Raman bands at 914 and 953 cm −1 are attributed to the antisymmetric vibrations. Intense prominent peaks observed at 3487, 3502, 3509, 3521 and 3547 cm −1 are assigned to the OH stretching vibration of the SiO 3 (OH) units. The observation of multiple OH bands supports the concept of the non-equivalence of the OH units. Vibrational spectroscopy enables a detailed assessment of the molecular structure of poldervaartite. [ABSTRACT FROM AUTHOR]

The mineral tengerite-(Y) has been studied by vibrational spectroscopy. Multiple carbonate stretching modes are observed and support the concept of non-equivalent carbonate units in the tengerite-(Y) structure. Intense sharp bands at 464, 479 and 508 cm −1 are assigned to YO stretching modes. Raman bands at 765 and 775 cm −1 are assigned to the CO 3 2 − ν 4 bending modes and Raman bands at 589, 611, 674 and 689 cm −1 are assigned to the CO 3 2 − ν 2 bending modes. Multiple Raman and infrared bands in the OH stretching region are observed, proving the existence of water in different molecular environments in the structure of tengerite-(Y). [ABSTRACT FROM AUTHOR]

In this work we have studied the mineral dawsonite by using a combination of scanning electron microscopy with EDS and vibrational spectroscopy. Single crystals show an acicular habitus forming aggregates with a rosette shape. The chemical analysis shows a phase composed of C, Al, and Na. Two distinct Raman bands at 1091 and 1068 cm −1 are assigned to the CO 3 2 − ν 1 symmetric stretching mode. Multiple bands are observed in both the Raman and infrared spectra in the antisymmetric stretching and bending regions showing that the symmetry of the carbonate anion is reduced and in all probability the carbonate anions are not equivalent in the dawsonite structure. Multiple OH deformation vibrations centred upon 950 cm −1 in both the Raman and infrared spectra show that the OH units in the dawsonite structure are non-equivalent. Raman bands observed at 3250, 3283 and 3295 cm −1 are assigned to OH stretching vibrations. The position of these bands indicates strong hydrogen bonding of the OH units in the dawsonite structure. The formation of the mineral dawsonite has the potential to offer a mechanism for the geosequestration of greenhouse gases. [ABSTRACT FROM AUTHOR]

The fourth member of the series of compounds of the type POX 3 with X = I was synthesized and characterized by infrared spectroscopy. The geometrical parameters and vibrational properties of POX 3 (X = F, Cl, Br, I) molecules were investigated theoretically by means DFT and ab initio methods. Available geometrical and vibrational data were used together with theoretical calculations in order to obtain a set of scaled force constants. The observed trends in geometrical parameters are analyzed and compared with those obtained in a previous work for the VOX 3 (X = F, Cl, Br, I) series of compounds. NBO analysis was performed in order to know the hyper-conjugative interactions that favor one structure over another. The molecular properties such as ionization potential, electron affinity, electronegativity, chemical potential, chemical hardness, softness and global electrophilicity index have been deduced from HOMO–LUMO analysis. [ABSTRACT FROM AUTHOR]

A brief overview on the recent applications of infrared and Raman spectroscopy in the field of art forensics is presented. [ABSTRACT FROM PUBLISHER]

A new organic–inorganic hybrid material, 1,4-bis(3-ammoniumpropyl) piperazinium pentachloridocuprate(II) chloride tetrahydrate [(C 10 H 28 N 4 )CuCl 5 Cl⋅4H 2 O], has been synthesized and characterized by X-ray diffraction, UV–visible absorption, Infrared and Raman spectroscopy. The compound crystallizes in the orthorhombic system and Pnma space group with a = 8.18 (3) Å, b = 10.96 (5) Å, c = 21.26 (9) Å, V = 2254.3 (15) Å 3 . In this structure, the Cu 2+ ion, surrounded by five chlorides, adopts the square pyramidal coordination geometry. The structure of this compound consists of tetraprotonated 1,4-bis(3-ammoniumpropyl) piperazinium cations and the anionic sublattice is built up of isolated, square pyramid [CuCl 5 ] 3 − units, chloride ion Cl − and water molecules connected with each other by hydrogen bonds. Organic and inorganic entities are interconnected by means of hydrogen bonding contacts [N H⋯O(Cl), O(W) H⋯Cl and O(W) H⋯O]. Furthermore, the room temperature IR and Raman spectra of the title compound were recorded and analyzed on the basis of literature data. The optical study was also investigated by UV–Vis absorption. In fact, the organic–inorganic hybrid crystal thin film can be easily prepared by spin-coating method from the ethanol solution of the (C 10 H 28 N 4 )CuCl 5 Cl⋅4H 2 O hybrid compound and it showed absorptions characteristics of Cu Cl based layered compounds centered at 275 and 374 nm. [ABSTRACT FROM AUTHOR]

The present paper reports the chemical synthesis, structure study, thermal analysis, and vibrational properties of new hybrid compound called: bis (adeninium) selenate bihydrates. It is crystallized in the triclinic system with P-1 space group and the following parameters a = 7.804(5) Å; b = 9.686 (5) Å; c = 11.771 (5) Å; α = 84.421(5)°; ß = 77.556(5)°; γ = 81.186 (5)°; Z = 2 and V = 856.7(8) Å 3 . The structure is built up from tunnels containing all the components of the structure and following to the c axis, linked via three types of hydrogen bonds (N H…O, N H…N and O H…O). The thermal decomposition of precursors studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), indicate the existence of two mass loss region correspond to dehydration and degradation of the title compound, respectively. The existence of vibrational modes correspond to the organic and inorganic groups and water molecular are identified by the IR and Raman spectroscopy in the frequency ranges 400–4000 and 300–1600 cm −1 , respectively. [ABSTRACT FROM AUTHOR]