摘要:

AbstractA design of a high‐temperature cell (used with a Spex‐1403 Ramalog spectrophotometer) for Raman studies with 90° geometry is given. Raman spectra of normal (d0) and denteriated (d12) tetramethylammonium chlorides in phases III and II are reported, together with their assignments. On the basis of the temperature dependence of the thermosensitive bands, the III → II phase transition was found at 367 ± 2 K for normal (d0) tetramethylam monium chloride and at 407±5 K for deuteriated (d12) tetramethylammonium chloride. It is observed that the III → II phase transition is irreversible if the samples are kept under vacuum during the investigation. Traces of moisture present in the samples are responsible for the stability of the room‐temperatu

ISSN:0377-0486    

DOI:10.1002/jrs.1250150402

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

Abstract4, 4′‐Difluorobiphenyl‐d8was synthesized by two routes and its infrared and Raman spectra were recorded. These were analysed with the assistance of calculated frequencies using a force field based on fluorobenzenes and using phase effects. A perturbation treatment of the frequencies of biphenyl, of its 4, 4′‐difluoro derivative and of their fully deuteriated isotopomers yielded a refined force field essentially in accord with previous aromatic fields. By studying the changes in the frequencies of certain skeletal modes on going from crystal to solution, the dihedral angle of the difluoro compound was shown to be very similar to that of biphenyl itself in solution (35–40°). There is, however, a possibility that the present model underestimates the in‐planeB1gskeletal deformation mode. In this case the biphenyl dihedral angle will be slightly overestimated and that of 4, 4′‐difluorobiphenyl slightly underestim

ISSN:0377-0486    

DOI:10.1002/jrs.1250150403

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractEvidence is provided concerning the internal rotation of the CHCl2group in the C6H5CHCl2molecule in the condensed phase using mainly the Raman spectra of the alkylic carbon‐hydrogen stretching vibration of C6H5CHCl2and its deuteriated analogues. Comparison of the Raman bands observed in the region of the CH stretching vibrations for the hydrogenated compound with its deuteriated derivatives allows the assingnment of two Raman bands to the CH vibrator of the CHCl2group. The dependence of the profiles of these bands on temperature and dilution in a series of solvents suggests a conformational equilibrium. Comparision of two different theoretical treatments of the isolated molecule enables us to reconize the importance of non‐boarded interactions operating during the internal rotation of the dichloromethyl group. The experimental results, used together woth the theoretical studies, lead to the evidence for two probable rotational isomers, designated CH⊥and CH‖which are responsible for the two observed Ra

ISSN:0377-0486    

DOI:10.1002/jrs.1250150404

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractNew experimental IR and Raman data have been obtained for 5‐aminotetrazole in the solid state and in aqueous solution. The band pattern observed between 1100 and 1000 cm−1in the Raman spectrum of the hydrated crystals has been interpreted in terms of Fermi resonance of a state associated with the tetrazole ring breathing mode and a two‐phonon state associated with the first overtone of a water libr

ISSN:0377-0486    

DOI:10.1002/jrs.1250150405

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe Raman intensities of lattice vibrations in crystalline naphthalene at room temperature have been calculated and compared with experimental results. The contribution of the local field and the effect of two‐centre representation of the molecular polarizability are discusse

ISSN:0377-0486    

DOI:10.1002/jrs.1250150406

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe Raman spectra of solid and liquid perfluoromethyl oxalate and its IR spectra in the gaseous, solution (CCl4) and solid phases have been recorded. The fluorine NMR spectrum of the substance in CCl4solution has also been obtained. A comparison of the vibrational spectra in the solid and fluid phases shows that perfluoromethyl oxalate exists in the fluid phases as a conformational mixture, whereas in the solid phase it seems to exist as a single conformer oftrans‐planarC24structure. A band assignment has been attempted for the normal vibrational modes of this conforme

ISSN:0377-0486    

DOI:10.1002/jrs.1250150407

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe isotropic Raman linewidth of isopropanol at 818 cm−1assigned to the CO stretching vibrational mode has been measured at a variety of concentrations in aqueous solution and in nonpolar tetrachloroethylene solution. On the basis of the concentration dependence of the linewidths observed in tetrachloroethylene solution, the isotropic Raman linewidth of the observed line is found to reflect the molarity of the hydrogen bonds of isopropanol. The unusual concentration dependence of the linewidths observed in aqueous solution, which shows a prominent maximum at a low concentration of isopropanol, has been examined in the light of these considerations. As a result, it is concluded that the concentration dependence of the linewidth is well explained in terms of the change in the partial molar volume of isopropanol, reflecting the change in the hydration structure in aqueous solution, and that the isotropic Raman linewidth of isopropanol is determined essentially by hydrogen bonding as an inhomogeneous broadening mechanism, other factors such as the vibrational dephasing being of less significa

ISSN:0377-0486    

DOI:10.1002/jrs.1250150408

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractRaman and infrared vibrational spectra have been recorded foro‐phthalic acid as a single crystal, as a powder and in solution. The proposed assignment of the observed frequencies was made on the basis of a normal coordinate analysis and symmetry considerations of the crystal spectrum, which allowed the separation of internal vibrations of theAandBspecie

ISSN:0377-0486    

DOI:10.1002/jrs.1250150409

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe Raman spectra of solid fully deuteriated syndiotactic (D8s‐PMMA, 55%) and undeuteriated isotactic (H8i‐PMMA, 92%) poly(methyl methacrylate) have been recorded in the 3500–200 cm−1range at ambient temperature. Vibrational assignments are proposed for most of the observed bands and, in the case of D8s‐PMMA, the data have resolved some of the inconsistencies in the spectra of the undeuteriate

ISSN:0377-0486    

DOI:10.1002/jrs.1250150410

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractPreliminary experiments using Perot‐Fabry interferometers demonstrated the possibility of filtering selectively the fluorescence background from Rayleigh scattering excited by 25 ps pulses. Experiments aimed at extending the technique to spontaneous, Raman scattering are in progress. This technique is compatible with either single‐channel or multi‐channel detection of Raman spectra excited by mode‐locked ion, dye or solid‐sta

ISSN:0377-0486    

DOI:10.1002/jrs.1250150411

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY