摘要:

AbstractRaman and infrared spectra of liquid 1,1,3,3‐tetramethyldisiloxane were recorded in the ranges 100–3500 and 400–4000 cm−1, respectively. A normal coordinate analysis based on a generalized valence force field was carried out. Using the potential energy distributions and the atomic displacements, this investigation permitted a reasonable interpretation of the observed vibrational modes and a description of the coupling of these modes in the 100–1500 cm−1region where the spectra exhibit a comple

ISSN:0377-0486    

DOI:10.1002/jrs.1250240202

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractUsing a highly efficient Raman set‐up, which allows a Raman spectrum to be recorded in less than 1 s, morphology‐dependent resonances in optically levitated microdroplets of water–glycerol mixtures were studied. In addition to the output resonances, where the Raman frequency coincides with an electromagnetic sphere resonance, input resonances could also be demonstrated. The latter are observed when the evaporating droplet reaches a radius which, together with the wavelength of the incident laser lgith, fulfils the resonance condition for the cavity modes of a sphere. Preliminary results for droplet size change during evaporation of a particular droplet in the micrometre range are pres

ISSN:0377-0486    

DOI:10.1002/jrs.1250240203

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractSurface‐enhanced Raman scattering (SERS) of thiourea [SC(NH2)2] was studied in acidic solutions of 0.1MH2SO4and 0.1MHCl. Very strong SERS bands of thiourea were observed in the acidic solutions, in contrast to very weak SERS spectra of thiourea in standard SERS solutions employing K2SO4or KCl. Thiourea seems to have a strong and stable surface adsorption at a silver electrode in the acidic solutions where protonation and anionic co‐adsorption may enhance this surface stability of thiou

ISSN:0377-0486    

DOI:10.1002/jrs.1250240204

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractSimultaneous space‐ and time‐resolved measurements of scalars were made in reacting and non‐reacting dilute, two‐phase, jet flows of methanol. The spontaneous Raman–Rayleigh scattering technique was used to measure temperature and the concentrations of CH3OH, O2, N2, H2, H2O, CO and CO2. In the reacting case, laserinduced fluorescence from the hydroxyl radical was jointly measured. The two‐phase flow is formed at atmospheric pressure at the exit of an axisymmetric jet centered in a co‐flowing stream of air. At the measurement location of ten fuel jet diameters downstream of the nozzle exit plane the volume percentage of liquid in the center of the jet is estimated at about 0.015%. The Rayleigh‐scattered signal can only be used as a marker for the existence of liquid in the measurement volume as it is overhwlemed by Mie and possibly geometrical scattering from droplets. The methanol Raman signal from the liquid–gas mixture increases, mainly owing to the increase in the number density of molecules and the local field effect. Raman signals from other gaseous species are not affected by the existence of droplets in the measurement volume. Gas‐phase temperature is obtained from the sum of the species number densities. The fluorescence from OH shows occasional unrealistic overshoots for rich mixtures, which indicates some interference due to the ex

ISSN:0377-0486    

DOI:10.1002/jrs.1250240205

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe vibrational Raman optical activity (ROA) spectra of the simple amino acidsL‐serine,L‐cysteine,L‐valine,L‐threonine andL‐isoleucine in aqueous solution between 600 and 1600 cm−1measured in backscattering are presented and discussed. Complete vibrational assignments are suggested for serine and cysteine and limited assignments for the others. Bands originating in Cα*H deformations and the symmetric CO2−stretch appear to provide the best signatures for stereochemical studies. The results show that ROA provides a new perspective on amino acid conformation in aq

ISSN:0377-0486    

DOI:10.1002/jrs.1250240206

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractSurface‐enhanced Raman scattering (SERS) spectra ofo‐,m‐ andp‐anisidine molecules were compared with the solution Raman spectra. The experimental results suggest that theo‐ andm‐anisidine molecules are adsorbed on the metal surface principally through the nitrogen atom, whereas thep‐anisidine molecules are adsorbed through the π‐system of the phenyl ring. This observation is explained in terms of the electron densities on the N and O atoms and in the phenyl ring as reflected by the Hammett σ values of the isomers. Charge‐transfer interactions have been shown to contribute si

ISSN:0377-0486    

DOI:10.1002/jrs.1250240207

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractRaman and infrared spectra of polycrystallinecisandtransisomers of the Mo(CO)4(PPh3)2complex were recorded at room temperature. The molecular vibrations around the central Mo atoms and the carbonyl ones were assigned and correlated with the group theoretical treatment. Some changes in the spectra of the triphenylphosphine ligand have also been discussed.

ISSN:0377-0486    

DOI:10.1002/jrs.1250240208

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractSurface Raman spectral studies of triphenylmethane dyes on colloidal silver were carried out. An assessment of the surface and solution spectra led to the conclusion that the dye molecules are most likely lying parallel to the surface of the sol and adoptingC3symmetry. The major vibrational changes suggest that the most important center of interaction is the central carbonium ion, since the greatest changes are observed for the vibrations of the central bonds and only small changes are observed for the N–phenyl stretching modes. For a fixed concentration of sol the lowest level of detection was 5 × 10

ISSN:0377-0486    

DOI:10.1002/jrs.1250240209

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractA procedure for the evaluation of rotational correction terms to polarizability derivatives from Raman spectra with respect to symmetry vibrational coordinates is described. The formulation developed is illustrated with calculations on a number of molecules.

ISSN:0377-0486    

DOI:10.1002/jrs.1250240210

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractComplete Raman spectra of all four fundamentals of pertechnetate, perrhenate and periodate ions in aqueous solution were measured and calibrated against NaClO4, as an external standard. Electro‐optical parameters for the TcO, ReO and IO bonds were calculated. Changes in the previously published force fields were necessary to adjust the eigenvectors to the experimental frequencies and intensities in an aqueous environment. Equilibrium bond polarizabilities were estimated from refractive index measurements in connection with Raman intensities of thev2bending modes. The results are discussed in connection with the ionic size of the XO4−anions and behaviour of perrhenate and pertechnetate ions in extraction

ISSN:0377-0486    

DOI:10.1002/jrs.1250240211

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY