摘要:

AbstractThe isotropic and anisotropic Raman spectra of a diatomic molecule, HCl, have been recorded in the gaseous state, in the liquid state and in solution in various solvents giving increasing interaction with the solute. It will be shown that the depolarization ratio increases with the interaction forces with the solvent, reflecting the appearance of an induced polarizability by molecular interaction on the solute. A linear relationship has been obtained between the ratio of the polarizability component derivatives (α‖/α⟂) and the frequency shift (Vgas—Vsolution). A non‐coincidence of the maximum of the isotropic and anisotropic spectra is also observed and interpreted as resulting from a frequency distribution of a series of solute molecules, involved differently in the interaction with th

ISSN:0377-0486    

DOI:10.1002/jrs.1250080102

出版商:John Wiley&Sons, Ltd.    

年代:1979

数据来源: WILEY

摘要:

AbstractResonance and pre‐resonance Raman spectra are presented for the 1:1 and 3:1 solid complexes of perylene with tetracyanoquinodimethane (TCNQ). Selective resonance enhancement was observed for perylene. A study of the frequency dependence of the Raman intensities shows that, although these are weak complexes, complexing has a marked influence on the scattering intensitie

ISSN:0377-0486    

DOI:10.1002/jrs.1250080103

出版商:John Wiley&Sons, Ltd.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe Raman signals from modes ν1, ν2, ν3, 2ν2, and 2ν8, of 1,1,1‐trichloroethane have been examined by varying the concentration of this molecule in several solvents. In addition temperature studies were conducted, including data from the disordered solid phase of the neat sample. The results of these studies show that (a) the fundamentals (ν1, ν2, and ν3) are involved in a dephasing process controlled by the intramolecular potential function, (b) dephasing processes of the overtones are dominated by intermolecular processes and (c) the ν2and ν3modes of this molecule show very little dilution effects (some broadening), whereas the same modes of the structurally similar molecule CH3I show a definitenarrowingin similar solvents. The theoretical model, proposed by Rothschild, is used to strengthen the interpretative case offered for the mechanistics of the dephasing processes of the fundam

ISSN:0377-0486    

DOI:10.1002/jrs.1250080104

出版商:John Wiley&Sons, Ltd.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe resonance Raman effect is reported for the bipyridyl ligand vibrations in the complexes {Fe(bipy)3}+2, {Fe(bipy)2(CN)2} and {Fe(bipy)(CN)4}−2. The Raman spectra were obtained using exciting laser line frequencies coincident with the visible metal–ligand charge transfer absorption bands. The identity of the resonantly enhanced Raman bands is correlated with the nature of the absorption bands. The resonantly enhanced excitation profiles of the bipyridyl vibrations are analyzed in terms of the theory of resonance Raman scattering. The results indicate that the high frequency components of these bands are primarily due to a superposition of the vibrational progressions of the symmetric ligand stretching modes and not due to additional charge transfer absorpti

ISSN:0377-0486    

DOI:10.1002/jrs.1250080105

出版商:John Wiley&Sons, Ltd.    

年代:1979

数据来源: WILEY

摘要:

AbstractResonance Raman spectra of protonated and unprotonated Schiff bases of all‐transretinal with propylamine, hexylamine, butylamine, deuterated butylamine (d9), methylamine and N15methylamine have been obtained. The spectra of methylated and deuterated butylamine Schiff bases of retinal have also been recorded. It was found that the carbon–nitrogen stretching vibration associated with the Schiff base is insensitive to changes in the mass and/or length of the saturated hydrocarbon group attached to the Schiff base except for the case of methylamine. The fingerprint region, on the other hand, is sensitive to alterations in the Schiff base substituent. Deuterating the Schiff base has a larger effect on the carbon–nitrogen stretching frequency than replacing the Schiff base nitrogen N14with N15. Furthermore, the data on deuterated Schiff bases indicate that the CCH bending vibrational mode is altered by deuteration. Implications concerning use of these compounds for modelling visual pigments and bacteriorhodopsin are

ISSN:0377-0486    

DOI:10.1002/jrs.1250080106

出版商:John Wiley&Sons, Ltd.    

年代:1979

数据来源: WILEY

摘要:

AbstractMeasurements of polarized Raman intensities of partially oriented molecules were shown to be useful for obtaining information about the components of the scattering tensor and the degree of orientation in anisotropic samples. The polarized resonance Raman (RR) spectra of all‐trans‐1,14‐diphenyltetradecaheptaene (DPTH) incorporated in a stretched polyethylene film were studied. The DPTH molecules are highly oriented in the polymer matrix with their longitudinal axis in the direction of stretching. The different components of the scattering tensor for the totally symmetric vibrations of DPTH were determined in the case of resonance excitation. It was found that the diagonal element αzz(z is defined along the polyene chain) gives the largest contribution to the RR intensity. However, the two off‐diagonal elements αzyand αyzalso contribute significantly and have different magnitudes. The physical origin of these off‐diagonal elements and of the asymmetry of the scattering tensor are discussed in terms of the vibronic cou

ISSN:0377-0486    

DOI:10.1002/jrs.1250080107

出版商:John Wiley&Sons, Ltd.    

年代:1979

数据来源: WILEY

摘要:

AbstractData are presented on the second order Raman spectrum of rutile TiO2for various scattering geometries, at room and liquid N2temperatures. The results of a standard critical point analysis (i) allow the most important addition processes at low energies to be identified, (ii) indicate the importance of matrix element effects, and (iii) cannot account for a peak at 172 cm−1for theY(xy)Xgeometr

ISSN:0377-0486    

DOI:10.1002/jrs.1250080108

出版商:John Wiley&Sons, Ltd.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe solvent‐subtracted Raman spectrum of hyaluronic acid is reported. The spectrum is unchanged by (i) variations in the pH of the solution 6.0–8.5, when buffered at constant ionic strength 0.1, and (ii) changes in temperature 10–50°C.As rheological, flow birefringence, and linear dichroism studies of hyaluronate solutions indicate a large and abrupt structural transition across the physiological pH range 7.0–7.5, the negative finding reported here is of considerable interest in contrast with those previous studies. When considering the polysaccharides in general, as precise rheological, flow birefringence and linear dichroism data are only available for hyaluronic acid, the present finding is of interest for hyaluronic acid considered as a model polysaccharide system exhibiting elasticity.The result reported here is discussed within the context of, on the one hand, the possible limitations of the Raman technique which is a probe ofg‐state vibrational modes and, on the other hand, the possible extension of the Raman technique to probing oriented (stressed) samples. As a previous study demonstrated a small limiting birefringence but a large limiting extinction angle with minimum change in monomer anisotropy for these solutions, the suggestion is favored that the abrupt structural transition across the physiological pH range previously reported is due to long‐range Van der Waals

ISSN:0377-0486    

DOI:10.1002/jrs.1250080109

出版商:John Wiley&Sons, Ltd.    

年代:1979

数据来源: WILEY

摘要:

AbstractSingle crystals of ytterbium, lutetium and scandium pyrosilicates were grown by a floating zone technique associated with an are image furnace. The recorded infrared and Raman spectra allow complete attribution of internal and external modes, in good agreement with group theory predictions.

ISSN:0377-0486    

DOI:10.1002/jrs.1250080110

出版商:John Wiley&Sons, Ltd.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe spectra ofm‐ nitroaniline solution in the middle infrared region (300–4000 cm−1) and in the Raman scattering region (150–1650 cm−1) as well as the polarized infrared (240–3500 cm−1) and Raman (170–1650 cm−1) spectra of monocrystalline samples of this compound have been measured. The dichroic ratios of infrared bands for (010) platelets and the depolarization ratios of the bands in the Raman spectra of acetone solution were determined and compared with theoretical values. On the basis of the results obtained and the assignments previously given by other authors, the assignments of all fundamentals ofm‐ nitoaniline have been either confirmed or proposed for the first time. Some relations between the electronic transition directions and the relative intensities of the infrared bands h

ISSN:0377-0486    

DOI:10.1002/jrs.1250080111

出版商:John Wiley&Sons, Ltd.    

年代:1979

数据来源: WILEY