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A new chalcone based chemosensor like 6-cinnamoylthiochroman-4-one (AZAN), has been designed and synthesized from 6-chlorothiochroman-4-one and cinnamaldehyde via keto ethylenic linkage. Its amino derivatives were synthesized by using urea (AZANU), thiourea (AZANTU) and 2,6-diamino pyridine (AZANPy) respectively and its metal ion sensing properties were investigated. The sensors can selectively recognize and sense the metal cations by showing different fluorescent characteristics at different concentrations. The fluorescence intensity shows remarkable enhancement by Cr 3+ over other common metal ions (Cd 2+ , Hg 2+ and Pb 2+ ). The proposed mechanism can be confirmed by UV-Vis and emission titration. The newly synthesized receptor can sense the metal ions even in nano molar level. The binding or association constant and detection limit of chemosensor to Cr 3+ are 1.684 × 10 5 M -1 and 0.2245 × 10 -9 M respectively. A computation using the density functional theory was done to gain detailed insights into the electronic structures of the ligand and its derivatives. B3LYP function and 6-31G(d,p) basis set were used to optimize the ground-state geometry of the chemical and its derivatives., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Multi-walled carbon nanotubes-fluorine-co-doped TiO2 composite was synthesized by the solid state method. The prepared photocatalysts were characterized by using XRD, FTIR and FE-SEM. In addition, the samples were evaluated for antimicrobial activity and photocatalytic activity. The composites exhibited enhanced absorption properties in the UV light range compared to pure TiO2. The MWCNTS-F-co-doped TiO2 composites showed significant photocatalytic activity in the generation of oxygen., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Silver nanoparticles have been synthesized by a simple and inexpensive solution combustion method with urea as fuel. The structural and morphology of the silver nanoparticles were investigated through X-ray powder diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersion Spectra (EDS) techniques. Structural and morphological results confirmed the nanocrystalline nature of the silver nanoparticles. Density Functional Theory (DFT) calculations were also performed to study the ground and excited state behavior of 2-bromo-1,4-naphthoquinone (2-BrNQ) and 2-BrNQ on silver nanoparticles. Surface-Enhanced Raman Scattering (SERS) spectra of 2-BrNQ adsorbed on silver nanoparticles were investigated. The CO, CH in-plane bending and CBr stretching modes were enhanced in SERS spectrum with respect to normal Raman spectrum. The spectral analysis reveals that the 2-BrNQ adsorbed 'stand-on' orientation on the silver surface. Density Functional Theory (DFT) calculations are also performed to study the vibrational features of 2-BrNQ molecule and 2-BrNQ molecule on silver surface., (Copyright © 2014 Elsevier B.V. All rights reserved.)

SERS provides essential data regarding the interaction of molecules in drugs with DNA. In the present study silver nanoparticles were synthesized using a solution combustion method with urea as fuel. The prepared silver nanoparticles are rod like structure. Surface-enhanced Raman scattering (SERS) of N-(1-2-bromophenyl)-2-(2-nitrophenyl)ethyl)-4-methylbenzenesulfonamide (BrS) adsorbed on the silver nanoparticle was studied. The nRs and Raman spectral analysis reveal that the BrS adsorbed tilted orientation on the silver surface. Vibrational modes of nRs along with HF calculations are also performed to study the HOMO and LUMO behavior and vibrational features of BrS., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Surface Enhanced Raman Spectroscopic technique has been employed to investigate the orientation of 2-bromo-3-methylamino-1,4-naphthoquinone (BMANQ) on silver nanoparticles. Silver nanoparticles have been prepared by solution combustion method with citric acid as fuel. Silver nanoparticles were characterized by X-ray Diffraction (XRD), High Resolution Transmission Electron Microscopy (HRTEM) and Scanning Electron Microscopy (SEM). XRD and morphological results confirmed the nanocrystalline nature of the prepared silver nanoparticles. The observed intense CO stretching, CBr stretching and NH2 vibration suggests that the BMANQ molecule may be adsorbed in a 'stand-on' orientation to the silver surface. The calculated highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy show that charge transfer occurs within the molecule., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The aqueous beetroot extract was used as reducing agent for silver nanoparticles synthesis. The synthesized nanoparticles were characterized using UV-visible spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The surface plasmon resonance peak of synthesized nanoparticles was observed at 438 nm. As the concentration of beetroot extract increases, absorption spectra shows blue shift with decreasing particle size. The prepared silver nanoparticles were well dispersed, spherical in shape with the average particle size of 15 nm. The prepared silver nanoparticles are effective in inhibiting the growth of both gram positive and gram negative bacteria. The prepared silver nanoparticles reveal faster catalytic activity. This natural method for synthesis of silver nanoparticles offers a valuable contribution in the area of green synthesis and nanotechnology avoiding the presence of hazardous and toxic solvents and waste., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Silver nanoparticles (Ag NPs) were prepared by solution combustion method with urea as fuel. Silver nanoparticles were characterized by UV-visible spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. Surface-enhanced Raman scattering (SERS) of 2-bromo-3-methyl-1,4-dimethoxy-9,10-anthraquinone (BMDMAQ) adsorbed on silver nanoparticles was investigated. The orientation of BMDMAQ on silver nanoparticles was inferred from nRs and SERS spectral features. Density functional theory (DFT) calculation was also performed to study the theoretical performance. The observed spectral features such as the high intensity of C-H out-of-plane bending mode and ring C-C stretching mode revealed that BMDMAQ adsorbed on silver surface through 'stand-on' orientation. Anthraquinone (AQ) derivatives have wide biomedical application which includes laxatives, antimalarials and antineoplastics used in the treatment of cancer. This present study would help to identify the interaction of drug molecules with DNA., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Silver nanoparticles (Ag NPs) of different sizes from 7nm to 22nm have been prepared by simple Dirk and Charles chemical method and characterized using UV-vis spectroscopy and high resolution transmission electron microscopy (HRTEM). Fluorescence quenching of 1,4-dimethoxy-2,3-dimethylanthracene-9,10-dione (DMDMAD) by silver nanoparticles has been investigated by fluorescence spectroscopy to understand the role of quenching mechanism. Furthermore, the intensity of DMDMAD fluorescence emission peak decreases with decrease in the size of the Ag NPs. The fluorescence quenching rate constant and association constant for above system were determined using Stern-Volmer and Benesi-Hildebrand plots. The mechanism of DMDMAD fluorescence quenched by Ag NPs was discussed according to the Stern-Volmer equation. It has been observed that the quenching due to Ag NPs proceeds via dynamic quenching process. The distance between DMDMAD (donor) to Ag NPs (acceptor) and the critical energy transfer distance were estimated based on the Förster Resonance Energy Transfer (FRET) theory., (Copyright © 2014 Elsevier B.V. All rights reserved.)

We report an extensive study on the evolution of a highly facile, selective colorimetric probe for Hg(2+) detection using cysteine modified silver nanoparticles. The nanoparticles are stable in a basic medium and the Surface Enhanced Raman Spectrum (SERS) reveal that the cysteine is bound to the Ag surface through the thiolate moiety with the charged carboxylate group pointing outwards in a morphology that lends itself to sensor applications. In the presence of Hg(2+), the absorption peak is quenched resulting in a drastic colour change. The sensor displays high selectivity to Hg(2+) over other metallic ions., (Copyright © 2014 Elsevier B.V. All rights reserved.)

In the present study, the silver nanoparticles were synthesized using a solution combustion method with urea as fuel. The prepared silver nanoparticles show an FCC crystalline structure with particle size of 59nm. FESEM image shows the prepared silver is a rod like structure. The surface-enhanced Raman scattering (SERS) spectrum indicates that the N-(1-(2-chlorophenyl)-2-(2-nitrophenyl)ethyl)-4-methylbenzenesulfonamide (CS) molecule adsorbed on the silver nanoparticles. The spectral analysis reveals that the sulfonamide is adsorbed by tilted orientation on the silver surface. The Hatree Fock calculations were also performed to predict the vibrational motions of CS. This present investigation has been a model system to deduce the interaction of drugs with DNA., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Green biogenic method for the synthesis of gold and silver nanoparticles using Solanum lycopersicums extract as reducing agent was studied. The biomolecules present in the extract was responsible for reduction of Au(3+) and Ag(+) ions from HAuCl4 and AgNO3 respectively. The prepared nanoparticles were characterized by UV-visible spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) technique to identify the size, shape of nanoparticles and biomolecules act as reducing agents. UV-visible spectra show the surface plasmon resonance peak at 546 nm and 445 nm corresponding to gold and silver nanoparticles respectively. Crystalline nature of the nanoparticles was evident from TEM images and XRD analysis. TEM images showed average size of 14 nm and 12 nm for prepared gold and silver nanoparticles respectively. FTIR analysis provides the presence of biomolecules responsible for the reduction and stability of the prepared silver and gold nanoparticles. XRD analysis of the silver and gold nanoparticles confirmed the formation of metallic silver and gold. The prepared gold and silver nanoparticles show good sensing and antimicrobial activity., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Silver nanoparticles (Ag NPs) of different sizes have been prepared by chemical reduction method and characterized using UV-vis spectroscopy and transmission electron microscopy (HRTEM). Fluorescence spectral analysis showed that the quenching of fluorescence of textile dyeing waste water (TDW) has been found to decrease with decrease in the size of the Ag NPs. Experimental results show that the silver nanoparticles can quench the fluorescence emission of adsorbed TDW effectively. The fluorescence interaction between Ag NPs (acceptor) and TDW (donor) confirms the Förster Resonance Energy Transfer (FRET) mechanism. Long range dipole-dipole interaction between the excited donor and ground state acceptor molecules is the dominant mechanism responsible for the energy transfer. Furthermore, photocatalytic degradation of TDW was measured spectrophotometrically by using silver as nanocatalyst under UV light illumination. The kinetic study revealed that synthesized Ag NPs was found to be effective in degrading TDW., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Silver nanoparticles were prepared using aqueous fruit extract of Ananas comosus as reducing agent. These silver nanoparticles showed surface plasmon peak at 439 nm. They were monodispersed and spherical in shape with an average particle size of 10 nm. The crystallinity of these nanoparticles was evident from clear lattice fringes in the HRTEM images and bright circular spots in the SAED pattern. The antibacterial activities of prepared nanoparticles were found to be size-dependent, the smaller nanoparticles showing more bactericidal effect. Aqueous Zn(2+) and Cu(4+) selectivity and sensitivity study of this green synthesized nanoparticle was performed by optical sensor based surface plasmon resonance (SPR) at room temperature., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Fluorine doped TiO2 were synthesized by solid state reaction method. Optical and structural properties of fluorine doped TiO2 were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, UV-vis diffusion reflectance spectroscopy and scanning electron microscopic techniques. The prepared fluorine doped TiO2 was smaller in size with respect to pure TiO2 and it is tetragonal in crystalline structure. Nanoflakes like structure of pure and fluorine doped TiO2 was confirmed from SEM image. Fluorine doped TiO2 shows smaller band gap, high strain and dislocation density when compared to pure TiO2. It also has higher photocatalytic activity with respect to pure TiO2., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Silver nanoparticles (Ag NPs) have been prepared by solution combustion method with glycine as fuel. Silver nanoparticles were characterized by X-Ray Diffraction (XRD), High Resolution Transmission Electron Microscopy (HRTEM) and UV-visible spectroscopy. The prepared silver nanoparticles exhibit cubic crystalline structure with grain size of 59 nm. HRTEM image shows that the silver nanoparticles have strain and four-fold symmetry formed by twinning in the crystal structure. The optical adsorption spectrum shows that the surface plasmon resonance peak of silver is observed at 380 nm. The orientation of 1,4-dibromonaphthlaene (1,4-DBrN) on silver nanoparticles has been inferred from nRs and SERS spectral features. The absence of a C-H stretching vibrations, the observed high intense C-H out-of-plane bending modes and high intense C-Br stretching vibration suggest that the 1,4-DBrN molecule may be adsorbed in a 'stand-on' orientation to the surface., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Silver nanoparticles were rapidly synthesized using Moringa oleifera flower extract as the reducing agent shows surface plasmon resonance peak at 439nm. The size and shape of the nanoparticles controlled by varying the concentration of M. oleifera flower extract in the reaction medium. The synthesized silver nanoparticles were well-dispersed spherical nanoparticles with the average size of 14nm. The retinoic acid present in M. oleifera flower extract used as reducing agent and proteins was responsible for capping of the bioreduced silver nanoparticles. The obtained nanoparticle shows size-dependent SERS activity. The SERS spectrum indicates that the pyridine adsorbed on the silver surface in a stand-on orientation via its nitrogen lone pair electrons., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Silver nanoparticles (Ag NPs) were synthesized by solution combustion method using glycine and citric acid as fuels. The prepared Ag NPs were characterized by optical absorption spectroscopy, X-Ray Diffraction (XRD), High Resolution Transmission Electron Microscopy (HRTEM), Fourier Transform Infrared spectroscopy (FTIR) and Energy Dispersion Spectroscopic (EDS) techniques. Surface plasmon resonance peak was appeared at 410 and 418 nm for glycine (GAg) and citric acid (CAg) assisted silver nanoparticles respectively. The silver NPs are fcc in crystal structure. The calculated average particle size from XRD was found around 29 nm for GAg and 41 nm for CAg. HRTEM image shows that the silver nanoparticles have strain and fivefold symmetry formed by twinning in the crystal structure. The photocatalytic activity of TiO2 nanoparticles with Ag NPs were also elucidated and were found that the Ag NPs enhance the photocatalytic activity of TiO2., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Copper oxide (CuO) nanoflowers were prepared by solution combustion method and glycine was used as fuel. The prepared nanoflowers are monoclinic in crystalline structure. FESEM and HRTEM studies confirmed the flower like structure of the CuO. The CuO nanoflowers were composed of wide nanopetals/sheets. CuO nanoflowers show very good photocatalytic activity. The apparent rate constant of this catalytic reaction was 0.016/min. The estimated direct band gap energy of the CuO was 3 eV., (Copyright © 2013 Elsevier B.V. All rights reserved.)

In the present study silver nanoparticles were synthesized using a solution combustion method with glycine as fuel. The prepared silver nanoparticles show an fcc crystalline structure with a particle size of 39 nm. Surface-enhanced Raman scattering (SERS) spectra of 2,3-dibromo-1,4-naphthoquinone (DBNQ) adsorbed on silver nanoparticles were investigated. The C-C stretching modes were enhanced and they were broaden in SERS spectrum with respect to normal Raman spectrum. The spectral analysis reveals that the DBNQ adsorbed flat-on orientation on the silver surface. DFT calculations are also performed to study the vibrational features of DBNQ., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Synthesis of silver nanoparticles using leaf extract of Hibiscus cannabinus has been investigated. The influences of different concentration of H. cannabinus leaf extract, different metal ion concentration and different reaction time on the above cases on the synthesis of nanoparticles were evaluated. The synthesized nanoparticles were characterized using UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). The prepared silver nanoparticles were monodispersed, spherical in shape with the average particle size of 9 nm and shows surface plasmon peak at 446 nm. The study also reveals that the ascorbic acid present in H. cannabinus leaf extract has been used as reducing agent. The prepared silver nanoparticle shows good antimicrobial activity against Escherichia coli, Proteus mirabilis and Shigella flexneri., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Preferential solvation of 1,4-dihydroxy-3-methylanthracene-9,10-dione (DHMAD) has been investigated using optical absorption and fluorescence emission techniques. Optical absorption spectra of DHMAD in different solvents show the intra molecular charge transfer band in the region 400-550 nm. The preferential solvation parameter shows that in dimethyl formamide (DMF)+carbon tetrachloride (CCl(4)) mixture, the DHMAD is preferentially solvated by DMF in the ground state and in the excited state DHMAD is preferentially solvated by CCl(4) in DMF rich region and by DMF in CCl(4) rich region., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Preferential solvation of 1,4-dimethoxy-3-methyl anthracene-9,10-dione (DMMAD) has been investigated using optical absorption technique. The preferential solvation parameters show that the DMMAD is preferentially solvated by acetone in acetone (AC)+propan-2-ol (PROH), AC+CH2Cl2 and AC+CCl4 mixtures. DMMAD prefers PROH in PROH+CCl4 mixture. In the case of benzene+CCl4 mixture DMMAD is preferentially solvated by benzene in benzene rich region and by CCl4 in CCl4 rich region. The results have been discussed in terms of hydrogen bonding, dipole-dipole and induced dipole-dipole interactions between DMMAD and solvent molecules., (Copyright © 2010 Elsevier B.V. All rights reserved.)

FTIR spectra of propionic acid (PA), 2-propanol (PROH) and its binary mixtures with varying molefraction of the PA were recorded in the region 500-3500 cm(-1), to investigate the formation of hydrogen bonded complexes in a mixed system. The observed features in nu(CO), nu(CO) and delta(COH) of PA, nu(CO) of PROH and delta(COH) of PA+PROH have been explained in terms of the hydrogen bonding interactions between PROH and PA and dipole-dipole interaction. The dipole moment derivative for the above mentioned vibrational modes have also been predicted from the integrated absorbance. The intrinsic linewidth for the vibrational modes nu(CO) and delta(COH) of PA has been elucidated using Bondarev and Mardaeva model., (Copyright 2009 Elsevier B.V. All rights reserved.)

FTIR spectra of propionic acid (PA), N,N-dimethyl formamide (DMF) and its binary mixtures with varying molefractions of the PA were recorded in the region 500-3500 cm(-1), to investigate the formation of hydrogen bonded complexes in a mixed system. The observed features in nu(C=O), delta(O=C-N) and nu(as)(CN) of DMF, nu(C=O) and nu(CO) of PA have been explained in terms of the hydrogen bonding interactions between DMF and PA and dipole-dipole interaction. The intrinsic bandwidth for the vibrational modes nu(as)(CN) and nu(CO) has been elucidated using Bondarev and Mardaeva model.

Preferential solvation studies of acridine have been investigated using optical absorption technique. The preferential solvation parameter shows that in dimethyl formamide (DMF)+ethanol mixture, the acridine is preferentially solvated by ethanol in DMF rich region and by DMF in ethanol rich region. In the case of DMF+Carbon tetrachloride mixture acridine is preferentially solvated by DMF.

Preferential solvation of a solvatochromic probe has been studied in binary mixtures comprising of a non-protic and a protic solvent. The non-protic solvents employed are carbon tetrachloride (CCl(4)), acetonitrile (AcN) and N,N-dimethyl formamide (DMF) and the protic solvents are methanol (MeOH) and ethanol (EtOH). The probe molecule exhibits different spectroscopic characteristics depending upon the properties of the solubilizing media. The observed spectral features provide an indication of the microenvironment immediately surrounding the probe. Solvatochromic shifts of the ground and excited states of the probe were analysed by monitoring the charge transfer absorption band and the fluorescence emission spectra in terms of the solute-solvent and solvent-solvent interactions. Fluorescence emission spectra show the dual emission due to excited state proton transfer nature of the probe molecule. The effect of solvent and the excitation energy on dual emission are also studied. The observed magnitude of the Stokes shift in the above solvents has been used to deduce experimentally the dipole moment ratio of the probe molecule for the excited state to the ground state. The dipole moment of excited state is higher than the ground state.

The optical absorption and IR spectra of 1,4-dimethylamino anthraquinone (1,4-DMAAQ) in CH(2)Cl(2)/C(2)H(5)OH mixtures have been investigated. The preferential solvation of 1,4-DMAAQ in CH(2)Cl(2)/C(2)H(5)OH mixed solvents has been studied by monitoring the charge transfer band of 1,4-DMAAQ. The optical absorption spectral study indicates that 1,4-DMAAQ is preferentially solvated by CH(2)Cl(2) in CH(2)Cl(2)/C(2)H(5)OH mixtures. This can be confirmed by the observed index of preferential solvation value (delta(s1)) as well as higher mole fraction of CH(2)Cl(2) in the solvation microsphere (x(1)(L)) than in the bulk solvent (x(1)). The CH(2)Cl(2) molecules become more available to enter the solvation shell of 1,4-DMAAQ because of the hydrogen bonded clusters formed by ethanol molecules. This is also evident from the non-linear behavior of the transition energy (E(12)) as well as the absence of synergistic behavior. IR spectral studies show that the observed shifts in the nu(CO) and nu(NH) of 1,4-DMAAQ are due to the dipole-dipole interaction between the 1,4-DMAAQ and the associated ethanol.

FT-IR and FT-Raman spectra were recorded and analyzed for l-valine l-valinium perchlorate monohydrate crystals. The wave number assignments have been made for the functional groups, viz. COOH, COO(-), --[NH(3)](+), C--(CH(3))(2), C--C--N and C--H. One of the two amino acid residues remains in the zwitterionic form while the other residue exists in the cationic form. The symmetry of the ClO(4)(-) anion has been found to be lowered corresponding to ClO(2) group. The hydrogen bonds that prevail between amino acid residues, perchlorate anion and water molecule influence the wave numbers of several stretching and deformation modes to deviate from the expected values.

The infrared and Raman spectra of L-lysine L-lysinium dichloride nitrate were recorded at room temperature and the vibrational assignments of the observed bands were made. The presence of both the carbonyl and ionized carboxylic groups has been identified in the title complex. The lysine and lysinium residues form a dimer through a strong O-H...O bond between them in the crystal. This together with the different environments has seen by the four -CH2- groups in each skeleton cause several of the functional group wavenumbers to occur as doublets or as broad bands. Some of the forbidden modes of the nitrate group have been observed. The extensive intermolecular hydrogen bonding in the crystal was identified by the shifting of bands due to the stretching and bending modes of the various functional groups.

The infrared and Raman spectra of bis(L-threoninium) sulphate monohydrate crystal have been recorded and analysed at room temperature. The proposed assignment of normal modes is based on group theoretical analysis. There is extensive intermolecular hydrogen bonding in the crystal and this is responsible for the changes in the position and intensity of several bands. The anion fundamentals continue to be degenerated which indicates that its symmetry is unaffected in the molecule.

The infrared and laser Raman spectra of L-methionine L-methioninium perchlorate monohydrate were recorded at room temperature and the vibrational assignments of the observed wave numbers were made. The presence of both the carbonyl and the ionized carboxylic groups has been identified in the title complex. The L-methionine and L-methioninium the cation have different conformations. This together with the different environment has seen by the two -CH(2)- groups in each skeleton cause several of the group wave numbers to occur as doublets or as broad bands. The perchlorate anion was found to be in the T(d) symmetry in the methionine environment. The coordination to other ligands in the crystal through hydrogen bonding does not affect this symmetry. The extensive intermolecular hydrogen bonding in the crystal was identified by the shifting of bands due to the stretching and bending modes of the various functional groups. Fermi resonance has also been observed.

Nano structured noble metals have very important applications in diverse fields as photovoltaics, catalysis, electronic and magnetic devices, etc. Here, we report the application of dual beam thermal lens technique for the determination of the effect of silver sol on the absolute fluorescence quantum yield (FQY) of the laser dye rhodamine 6G. A 532 nm radiation from a diode pumped solid state laser was used as the excitation source. It has been observed that the presence of silver sol decreases the fluorescence quantum efficiency. This is expected to have a very important consequence in enhancing Raman scattering which is an important spectrochemical tool that provides information on molecular structures. We have also observed that the presence of silver sol can enhance the thermal lens signal which makes the detection of the signal easier at any concentration., (Copyright 2003 Elsevier B.V.)

Optical absorption, fluorescence emission and surface enhanced Raman spectra of 1,5-dipiperidino anthraquinone (1,5-DPAQ) have been examined to elucidate the nature of molecule in different environments. Fluorescence emission and optical absorption measurements show that the polarity of the solvent plays a vital role through intermolecular hydrogen bonding and reorientational motion of solvent molecule around excited state fluorophore. Anisotropy measurement gives the angle between absorption and emission transition dipoles. The vibrational features observed in surface enhanced Raman spectroscopy (SERS) suggest that the molecules are chemisorbed. The adsorption of the molecule is through pi electrons in the anthraquinone ring and the axial lone pair of electrons of nitrogen. The orientation of the molecule is found to be 'flat-on'.

Surface enhanced Raman spectrum of 1,4-dimethylamino anthraquinone (1,4-DMAAQ) adsorbed on silver particles has been analyzed to understand the interaction between the molecule and silver surface. By studying the band intensities, the orientation of the molecule is determined. The high intensity and frequency downshifted peak due to carbonyl stretching vibration plays a major role, which shows that the molecules are chemisorbed through coordinating sites. The new peaks observed due to C-N and N-H stretching vibrations also provide the evidence for adsorption through co-ordinating sites. Optical absorption and laser induced fluorescence spectra of this molecule have also been studied in different solvents to understand the effect of environment. Polarization and anisotropy measurements provide the change in orientation induced by solvent molecules between absorption and emission transition dipoles.