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Singh P, Deckert-Gaudig T, Schneidewind H, Kirsch K, van Schrojenstein Lantman EM, Weckhuysen BM, Deckert V. Differences in single and aggregated nanoparticle plasmon spectroscopy. Phys Chem Chem Phys 2014; 17:2991-5. [PMID: 25516108 DOI: 10.1039/c4cp04850d] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Vibrational spectroscopy usually provides structural information averaged over many molecules. We report a larger peak position variation and reproducibly smaller FWHM of TERS spectra compared to SERS spectra indicating that the number of molecules excited in a TERS experiment is extremely low. Thus, orientational averaging effects are suppressed and micro ensembles are investigated. This is shown for a thiophenol molecule adsorbed on Au nanoplates and nanoparticles.
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Affiliation(s)
- Pushkar Singh
- Leibniz Institute of Photonic Technology, Albert-Einstein-Str. 9, 07745 Jena, Germany
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Upadhyay G, Gomti Devi T. Raman bandshape analysis on CH and CSC stretching modes of dimethyl sulfoxide in liquid binary mixture: comparative study with quantum-chemical calculations. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2014; 133:250-258. [PMID: 24945866 DOI: 10.1016/j.saa.2014.05.043] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Revised: 05/13/2014] [Accepted: 05/14/2014] [Indexed: 06/03/2023]
Abstract
The interacting nature of dimethyl sulfoxide (DMSO) in binary mixtures has been carried out on CH and CSC stretching modes of vibration using chloroform (CLF), chloroform-d (CLFd), acetonitrile (ACN) and acetonitrile-d3 (ACNd) solvents. Peak frequencies of both the stretching modes show blue shift with the increase in solvent concentration. Variation of Raman bandwidth with the solvent concentration was discussed using different mechanisms. Ab initio calculation for geometry optimization and vibrational wavenumber calculation have been performed on monomer and dimer structures of DMSO to explain the experimentally observed Raman spectra. Theoretically calculated values are found in good agreement with the experimental results. Vibrational and reorientational relaxation times have been studied corresponding to solvent concentrations to elucidate the interacting mechanisms of binary mixtures.
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Affiliation(s)
- Ganesh Upadhyay
- Department of Physics, North-Eastern Regional Institute of Science and Technology, Arunachal Pradesh 791109, India.
| | - Th Gomti Devi
- Department of Physics, North-Eastern Regional Institute of Science and Technology, Arunachal Pradesh 791109, India.
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Upadhyay G, Devi TG. Raman spectroscopic study of polar aprotic molecule and its molecular associations with chemical and isotopic solvents: Comparative study with quantum-chemical calculations. J Mol Liq 2014. [DOI: 10.1016/j.molliq.2014.05.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Gomti Devi T, Upadhayay G. Solvent dependent Raman bandshape analysis on CO containing molecules: vibrational relaxation study. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2012; 91:106-112. [PMID: 22366620 DOI: 10.1016/j.saa.2012.01.064] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Revised: 01/16/2012] [Accepted: 01/24/2012] [Indexed: 05/31/2023]
Abstract
Solvent dependent Raman band studies of some carbonyl containing molecules have been carried out in chlorobenzene (CLB) and chloroform (CLF) solvents. The variation of bandwidth with the solvent concentration was discussed using different mechanisms. The vibrational and reorientational correlation times were studied corresponding to solvent concentrations. The reorientational correlation time follows with the liquid viscosity in molecules under study. It reflects about the nature of solvent molecules hindering to the orientational motion of solute in liquid solution.
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Affiliation(s)
- Th Gomti Devi
- Department of Physics, North-Eastern Regional Institute of Science and Technology, Arunachal Pradesh 791109, India.
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Ojha AK, Srivastava SK, Singh RK, Asthana BP. A New Approach to Explain Concentration-Dependent Changes of Isotropic Raman Line Width in the Associated Binary Mixtures. J Phys Chem A 2006; 110:9849-53. [PMID: 16898685 DOI: 10.1021/jp061397h] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report on a new empirical relationship to explain the concentration-dependent isotropic Raman line width changes of a vibrational mode in uniform binary mixtures. The factors contributing to the intrinsic line width and several other broadening mechanisms are, in general, concentration-dependent. Concentration fluctuation in a microscopic volume and microviscosity are the two factors that are known to cause a concentration-dependent line width variation. These two factors combined in a specific manner successfully explain the variation of the line width with concentration strongly associated with binary systems. A readily usable empirical relationship for line width is suggested. It has been demonstrated that it can successfully explain the line width variation with concentration in a given class of hydrogen-bonded systems taking some representative binary mixtures.
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Affiliation(s)
- Animesh K Ojha
- Department of Physics, Banaras Hindu University, Varanasi-221005, India
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Datta S, Kumar K. Vibrational relaxation studies in methyl acetate: role of microenvironment and hydrodynamic forces. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2006; 64:665-9. [PMID: 16386945 DOI: 10.1016/j.saa.2005.08.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2005] [Revised: 07/20/2005] [Accepted: 08/02/2005] [Indexed: 05/06/2023]
Abstract
The Raman spectra were recorded for the C=O stretching vibration of methyl acetate as solutions in various polar and non-polar solvents. The isotropic component was obtained and the vibrational relaxation rates were calculated. On the basis of dependence of isotropic Raman bandwidth on the hydrodynamic properties of the solute-solvent systems, the information was obtained on the microenvironment prevailing in the neighborhood of the C=O stretching mode. Significant correlation is observed between vibrational relaxation rate and solvent parameters namely viscosity, density, refractive index and molecular radius. Microviscosity, involving the size of solute and solvent molecules, is found to be crucial in determining the bandwidth, hence the relaxation rate. The microenvironment appears to play an important role in the vibrational relaxation process.
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Affiliation(s)
- Soma Datta
- Department of Physics, North Eastern Hill University, Shillong 793022, Meghalaya, India
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Musso M, Giorgini MG, Torii H, Dorka R, Schiel D, Asenbaum A, Keutel D, Oehme KL. The Raman non-coincidence effect of the 12CO stretching mode of liquid acetone in chemical and in isotopic mixtures. J Mol Liq 2006. [DOI: 10.1016/j.molliq.2005.11.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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9
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Devi TG, Kumar K. Anisotropy shift and Raman bandwidth studies in carbonyl containing molecule o-chlorobenzaldehyde: role of repulsive forces. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2005; 62:972-9. [PMID: 15950524 DOI: 10.1016/j.saa.2005.04.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2005] [Revised: 04/06/2005] [Accepted: 04/07/2005] [Indexed: 05/02/2023]
Abstract
The analysis of Raman anisotropy shift as a function of solvent concentration shows the weakening of pair interaction of the molecules due to the influence of solvent-induced perturbations. The present study deals with the effect of dielectric constant of the medium on the non-coincidence effect (anisotropy shift) and the role of van der Waals' volume on the anisotropic Raman bandwidth. The CO stretching vibration of o-chlorobenzaldehyde (OCBD) molecule was studied in various polar and non-polar solvents namely CCl4, CH3CN, C6H5Cl and CH3C6H5. The data on anisotropic bandwidth are interpreted using the van der Waals' volume within the framework of lineshape theory of Bratos and Tarjus, while the Onsager-Fröhlich model on non-coincidence effect has been tested. Our study shows that the repulsive potential of the type e-alphaR is playing an important role in the OCBD-solvent interactions. The vanishing of anisotropy shift (non-coincidence effect) on dilution may be explained on the basis of repulsive forces playing a significant role in solute-solvent interactions.
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Affiliation(s)
- Th Gomti Devi
- Department of Physics, North-Eastern Hill University, Shillong 793022, India
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Gomti Devi T, Das A, Kumar K. Raman anisotropic bandwidth study of C=O stretching vibration of methyl isobutyl ketone: role of van der Waals' volume of the interacting systems. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2004; 60:211-216. [PMID: 14670480 DOI: 10.1016/s1386-1425(03)00207-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The bandwidth (FWHM) of the anisotropic component (Gamma(aniso)) of methyl isobutyl ketone (MIBK) for different concentrations of solvents varying from 10 to 90% was measured and was plotted as a function of solvent concentrations. In lower solvent concentration, the graph shows a curvature with a discontinuity which occurs between 40 and 60% and in higher solvent concentration, the graph shows a straight line for most of the solvents. In order to interpret the complicated behaviour we have taken into accounts the van der Waals' volume (V(w)) of the sphere of influence in solute dissolved in all solvents. Considering the role of van der Waals' volume in these systems the parameter Gamma(omega)=ln(Gamma(aniso)/V(w)) was plotted at different solvent concentrations. The graph shows a straight line for the entire region. In order to study the influence of screening effect on the bandwidth, the capacitances of the liquid mixture at different solvent concentrations varying from 10 to 90% were measured for all the solvents. The plot of capacitance at different solvent concentrations for each solvent shows a discontinuity around 50% of solvent concentration.
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Affiliation(s)
- Th Gomti Devi
- Department of Physics, NEHU Campus, North-Eastern Hill University, Shillong 793022, Meghalaya, India
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Keutel D, Seifert F, Oehme KL, Asenbaum A, Musso M. Evidence for negative cross correlations in vibrational dephasing in liquids: isotropic raman-line shift and width phenomena in isotopic mixtures of N2 and O2. PHYSICAL REVIEW LETTERS 2000; 85:3850-3853. [PMID: 11041943 DOI: 10.1103/physrevlett.85.3850] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2000] [Indexed: 05/23/2023]
Abstract
To experimentally confirm the hypothesis of negative cross terms between different dephasing mechanisms, potentially leading to a broadening of the isotropic Raman line upon isotopic dilution, we present a detailed study on the concentration dependencies of all of the line shifts and widths in the four isotopic mixtures of type (15N14N)(x)-(14N2)(1-x), (15N2)(x)-(14N2)(1-x), (15N2)(x)-(15N14N)(1-x), and (16O2)(x)-(18O2)(1-x) near the normal boiling point of nitrogen at T = 77.35 K. A quite disparate behavior of the nitrogen oscillators compared to the oxygen oscillators was observed in respect to a change of their isotopic baths.
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Affiliation(s)
- D Keutel
- Institut fur Physikalische Chemie, Friedrich-Schiller-Universitat Jena, D-07743 Jena, Germany
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Marri E, Morresi A, Paliani G, Cataliotti RS, Giorgini MG. Isotopic and chemical dilution effects on the vibrational relaxation rate of some totally symmetric motions of liquid acetonitrile. Chem Phys 1999. [DOI: 10.1016/s0301-0104(99)00089-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Musso M, Asenbaum A, Keutel D, Seifert F, Oehme KL. Anomalous Behavior of Isotropic Raman Line Shapes near Gas-Liquid Critical Points. PHYSICAL REVIEW LETTERS 1996; 77:2746-2749. [PMID: 10062035 DOI: 10.1103/physrevlett.77.2746] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Moser G, Asenbaum A, Barton J, Döge G. Concentration dependence of the vibrational band shape and frequency in binary mixtures. J Chem Phys 1995. [DOI: 10.1063/1.468903] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Keutel D, Seifert F, Oehme K. Isotropic Raman line widths in binary mixtures of van der Waals liquids: A comparison between isotopically and chemically diluted states of liquid methyl iodide. J Chem Phys 1993. [DOI: 10.1063/1.465728] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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On the validity of reorientational correlation times: Liquid hydrogen bromide as an example. Chem Phys Lett 1990. [DOI: 10.1016/0009-2614(90)87097-b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Oehme KL, Klostermann K. Vibrational relaxation through the resonance coupling mechanism. J Mol Liq 1990. [DOI: 10.1016/0167-7322(90)80005-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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