摘要:

AbstractThe Raman spectra of gaseous, liquid and solid 1,1,1,3,3,3‐hexafluoro‐2‐methoxypropane, (CF3)2CHOCH3, and the corresponding methoxy‐d3isotope, (CF3)2CHOCD3, together with the infrared spectra of the gases and solids, have been recorded from 3500 to 30 cm−1. A comparison of the vibrational spectra obtained for the fluid phases with those obtained for the amorphous and annealed solids indicates the predominance of a single conformer at ambient temperature in the fluid phases with the same conformer present in the solid state. Based on the lack of depolarized Raman lines in the fluid phases, and a predominance of nondescript infrared band contours, it is concluded that the stable conformer is thegaucheform which has the methoxy group rotated approximately 60° from eclipsing the secondary carbonhydrogen bond. Thirty‐eight of the 39 normal modes have been assigned based on group frequencies, isotopic shifts, depolarization values and infrared band contours. There appears to be coupling of the CF3and methoxy torsional modes. Utilizing a coupled‐top barrier calculation, the barrier to internal rotation of the perfluoromethyl groups is estimated to be 2858 ± 100 cm−1(8.2 ± 0.3 kcal mol−1) based on the torsional frequencies of 107 and 64 cm−1observed in the solid phase. Several of the fundamentals appear as doublets in the spectra of the solids, which indicates that there are at least two molecules per primitive cell. These results are compared with similar data for some

ISSN:0377-0486    

DOI:10.1002/jrs.1250200102

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractRoom‐temperature and low‐temperature (10 K) Raman spectra of a single crystal NaH2PO4were obtained for various polarizations. The polarization characteristics of the Raman spectra remained unchanged throughout the whole temperature range studied. This confirms that there is no phase transition in this crystal at least down to 10 K. High‐frequency H modes showed the well knownABC‐type three‐band structure and correlated with OH…

ISSN:0377-0486    

DOI:10.1002/jrs.1250200103

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractIn the polarized Raman spectra of K3Mn(CN)6and K3Cr(CN)6, soft modes are observed in both the roomtemperature and the low‐temperature phases. The frequencies of these modes decrease as the transition temperatures [205 K for K3Mn(CN)6and 215 K for K3Cr(CN)6] are approached from both sides. Unambiguous spectroscopic evidence for the second‐order displacive phase transition was obtained on the basis of the soft mode behaviour in both crystals. High‐pressure Raman spectra of K3Cr(CN)6were measured up to 35 kbar using a diamond anvil cell. A pressure‐induced phase transition occurs atca

ISSN:0377-0486    

DOI:10.1002/jrs.1250200104

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractA Raman study of a geological fluorapatite with significant substitutions of Ca2+by Sr2+and Ce3+and some other minor impurities is reported. The spectra were measured at 10 K and at room temperature using excitation wavelengths of 488, 514.5 and 647.1 nm. Strong vibroelectronic transitions were observed and are explained in terms of the role played by the impurities.

ISSN:0377-0486    

DOI:10.1002/jrs.1250200105

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe Raman spectral bandwidths of twoA1′ vibrations of 1,3,5‐trifluorobenzene (TFB) were measured in the neat liquid as a function of temperature and in the solvents CH2Cl2and CS2. The Raman and IR linewidths of twoE′ modes were also measured in solution. Derived values of the two rotational diffusion constants,D⊥andD∥, were compared with the predictions of several current theories. It was observed that the Hynes–Kapral‐Weinberg (HKW) theory is superior to both the microviscosity–free rotor and Hu–Zwanzig ‘slip’ models of reorientational diffusion. Calculated values ofD⊥andD∥for TFB in solution using the HKW model are in excellent agreement with the experimentally mea

ISSN:0377-0486    

DOI:10.1002/jrs.1250200106

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractResonance Raman excitation profiles for a substituted phthalocyanine dispersed as a polycrystalline powder in a silver disc were compared with those for a Langmuir–Blodgett (LB) multilayer of the same material on a silicon surface. There is a strong angular dependence of the efficiency of the scattering process. The LB profiles are strongly influenced by the electronic fields from the smooth semiconducting silicon surface, which gives rise to increased π‐π* energy separation and comparatively efficient scattering from upper vibronic s

ISSN:0377-0486    

DOI:10.1002/jrs.1250200107

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe literature contains only very poor Raman spectra on several deeply coloured ions. In this paper, new spectra of high quality are given for the permanganate ion, obtained using Fourier transform Raman techniques and nearinfrared excitation. Several other tetraoxo compounds have also been studied by these techniques as a comparison.

ISSN:0377-0486    

DOI:10.1002/jrs.1250200108

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe Raman and infrared spectra of pimelic acid, (CH2)5[COOH (D)]2, and its potassium salts in aqueous solution were recorded from 4000 to 200 cm−1. The two salts belong to theCssymmetry point group whereas the acid hasC1symmetry. These results are similar to those found previously for lower alkanedloic acids with an odd number of carbon atoms, namely glutaric acid, (CH2)3(COOH)2, and malonic acid, CH2(COOH)

ISSN:0377-0486    

DOI:10.1002/jrs.1250200109

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractAccurate vibrational frequencies are reported for pyrazole and for sevenN‐ andC‐deuterated analogues from FT‐IR spectra for the vapour phase at room temperature, diluted CCl4solutions and polycrystalline solids and from Raman spectra in aqueous solutions. Several frequencies are reported for fundamentals not previously observed in the vapour phase in particular. Assignments were carried out by performing a normal coordinate analysis for in‐plane and out‐of‐plane modes, using either Urey–Bradley or general valence force fields. Great care was taken to determine a refined force constant set which agrees as far as possible with observed isotopic shifts. A detailed description of all the normal modes and atomic displacements for in‐plane

ISSN:0377-0486    

DOI:10.1002/jrs.1250200110

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe infrared and Raman spectra of [NH3CH2CH2NH3](VO3)2were recorded and are briefly discussed. The vibrational behaviour of this compound resembles that of previously investigated MIVO3metavanadates, which also possess a closely related chain structure.

ISSN:0377-0486    

DOI:10.1002/jrs.1250200111

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY