摘要:

AbstractAssignments are proposed for the IR and Raman spectra of potassium, zinc and mercury(II) nicotinates and for the UV‐visible spectra of the f → f transition for erbium nicotinate. The influence of K, Zn, Hg(II), Nd(III), Dy(III) and Er(III) on the aromatic system of nicotinic acid was studied. There are essential differences in the number, wavenumber and intensity of aromatic system bands in the ranges of the ring modes, (1610–1400 cm−1), γ(CH) (970–700 cm−1) and Φ(CC) (700–650 cm−1), depending on the central ion. Potassium and mercury(II) perturb but lanthanides stabilize the aromatic system of nicotinic acid. The wavenumbers and intensities of some vibrational bands of the aromatic system depend systematically on the ionic potenti

ISSN:0377-0486    

DOI:10.1002/jrs.1250241202

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe Raman spectra of trihalides of the Fifth Group, BiCl3, AsCl3, AsBr3, SbBr3and PCl3, in the gas, liquid and solid were obtained. A normal coordinate analysis was performed. The intermolecular force constants were calculated from variations of the intramolecular force constants of the molecule during the phase transition. The half‐periods of librations in the liquid and lattice frequencies in the crystal were calculated and the lattice spectrum of the crystal was interpreted. It is shown that for a heavy central atom the calculation of intermolecular force constants may be performed in the approximation of a diagonal potential energy matrix. For a light central atom such an approximation may be used only for estimates. In this case the use of a complete potential energy matrix of a molecule is necessary for an accurate calculatio

ISSN:0377-0486    

DOI:10.1002/jrs.1250241203

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractPolar and axial tensorial covariants without intrinsic symmetries have been calculated using the method of representation theory up to rank 4 for the 32 crystallographic, the 5 pentagonal, the 2 icosahedral, the 7 decagonal and the 5 continuous one‐parametric classical point groups (Curie limiting point groups). The full results have been published as tables by the Fachinformationszentrum Karlsruhe. This paper reviews the general method of calculation, which is based on representation theory using an extension of Neumann's principle. The results are compared critically with various complications of special cases in the literature and a number of errors and inconsistencies are pointed ou

ISSN:0377-0486    

DOI:10.1002/jrs.1250241204

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractHigh‐pressure Raman spectra of liquid and crystalline CHF2Cl and CHF3were measured up to pressures of 15 and 10 GPa, respectively, at 300 K in a gasketed diamond‐anvil cell. The liquid–solid phase transition pressures were determined to be 3.49 GPa for CHF2Cl and 2.46 GPa for CHF3. For both CHF2Cl and CHF3, the wavenumbers of the CH stretching mode ν1increased rapidly with increasing pressure, and this behaviour was investigated by the theory of reasonance hybrid of the covalent‐bonded and ionic‐bonde

ISSN:0377-0486    

DOI:10.1002/jrs.1250241205

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe Raman spectra (3400–10 cm−1) of gaseous, liquid and solid and the infrared spectra (3500–35 cm−1) of gaseous and solid cyanomethyl methyl ether (methoxyacetonitrile), (CN)CH2OCH3, were recorded. The farinfrared spectrum of the gas was recorded at a resolution of 0.10 cm−1in the region from 370 to 30 cm−1. The fundamental asymmetric torsions of thegaucheandtransconformations were observed at 112.5 and 104.6 cm−1, respectively, with thegaucheform having two excited‐state transitions falling to lower wavenumber. From these data, along with the enthalpy difference andgauchedihedral angle, the asymmetric torsional potential function was calculated with the following coefficients: V1= 153 ± 9, V2= −619 ± 8, V3= 1000 ± 2 and V4= −100 ± 2 cm−1. From this potential function, thetrans to gauche, gauche to gaucheandgauche to transbarriers were determined as 512, 1592 and 951 cm−1, respectively, with an enthalpy difference of 439 ± 19 cm−1(1255 ± 54 cal mol−1) and thegaucheconformer the more stable form in the gas phase. The enthalpy difference was also determined experimentally from variable‐temperature studies of the Raman spectrum and a value of 337 ± 44 cm−1(964 ± 126 cal mol−1) was obtained for the liquid with thegaucheform more stable. Additionally, the symmetric methyl torsions of bothgaucheandtransforms were observed at 170.4 and 217.6 cm−1, respectively. On the basis of a one‐dimensional model, the barrier to internal rotation of the methyl moiety was determined as 839 cm−1(2.40 kcal mol−1) for theguacheconformer and 947 cm−1(2.71 kcal mol−1) for thetransform. A complete vibrational assignment is proposed for agauche‐transequilibrium in the gas and liquid phases from the Raman (3200–10 cm−1) and infrared (3200–35 cm−1) spectra, but in the solid state only thegaucheconformer remains. The structural parameters, conformational stability, barriers to internal rotation and fundamental vibrational frequencies which were determined experimentally were compared with those obtained fromab initiocalculations employing the RHF/4–31G*, RHF/6–31G* and MP2/6–31 + + G** basis sets. These results were compared

ISSN:0377-0486    

DOI:10.1002/jrs.1250241206

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractResonance Raman spectra of iron(II) protoprophyrin IX [Fe(II)PP] in dimethyl sulfoxide (DMSO) and deuterated DMSO were obtained at high and low photon densities using 10 ns laser pulses. At low photon density, comparison of the Raman spectra of the complex with those of carbonmonoxy‐hemoglobin indicates that a low‐spin, six‐coordinate (DMSO)2Fe(II)PP complex exists; at high photon density, spectral comparisons with deoxyhemoglobin and the 2‐methylimidazole heme complex (2‐MeIm)Fe(II)PP indicate that a transient high‐spin, five‐coordinate complex is formed by photodissociation of a DMSO ligand. This phenomenon is reversible and observable on a 10

ISSN:0377-0486    

DOI:10.1002/jrs.1250241207

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractPolarized Raman spectra of methylammoniummercury trichloride crystals were measured at room temperature. Factor group analysis involving the correlation method was applied. The observed spectra were interpreted in terms of internal and external oscillations of the constituent molecular ions, CH3NH3+and HgCl3

ISSN:0377-0486    

DOI:10.1002/jrs.1250241208

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe relationships between the valence optical theory of Raman intensities and the atomic polarizability tensors model were studied. It is shown that the atomic polarizability tensors can be expressed in terms of electro‐optical parameters. The theoretical relationships derived are illustrated with a numerical exampl

ISSN:0377-0486    

DOI:10.1002/jrs.1250241209

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractMonobeam transmission and resonance Raman (RR) experiments were used to study the excited stateSm←S3(B) spectra and the depolarization ratios, ρn, of the ν2(Cβ–Cβ),A1g,\documentclass{article}\pagestyle{empty}\begin{document}$ \Delta \mathop \nu \limits^ - = 1558{\rm cm}^{ - {\rm 1}} $\end{document}, and δ(pyr),A1g,\documentclass{article}\pagestyle{empty}\begin{document}$ \Delta \mathop \nu \limits^ - = 1643{\rm cm}^{ - {\rm 1}} $\end{document}RR peaks ofmeso‐tetrakis(N‐methyl‐4‐pyridyl)porphine, H2TMpyP(4), in phosphate buffer (pH 7) at an excitation of λ1= 422 nm (\documentclass{article}\pagestyle{empty}\begin{document}$ \Delta \mathop {\nu _1 }\limits^ - = 23697{\rm cm}^{ - {\rm 1}} $\end{document}) as a function of pump intensity,I1(mW), over the range ofI1= 0–5 mW. Three factors, ground state depletion, induced anisotropic density distribution of the ground stage,n1G, and the anisotropic polarized excited‐state absorption effect, are discussed to explain the behaviour of ρnversusI1for these two peaks. In addition, scattering tensors and experimentally determined depolarization ratios for the\documentclass{article}\pagestyle{empty}\begin{document}$ \Delta \mathop \nu \limits^ - = 1558{\rm cm}^{ - {\rm 1}} $\end{document}and\documentclass{article}\pagestyle{empty}\begin{document}$ \Delta \mathop \nu \limits^ - = 1643{\rm cm}^{ - {\rm 1}} $\end{document}RR peaks of H2TMpyP(4) at excitations of λ1= 422, 476.5 and 514.5 nm (\documentclass{article}\pagestyle{empty}\begin{document}$ \Delta \mathop \nu \limits^ - = 23697,{\rm 20986 and 19436 cm}^{ - {\rm 1}} $\end{document}, respectively) are presented. The results seem to imply thata>b, and could be interpreted as the presence ofx‐ andy‐sp

ISSN:0377-0486    

DOI:10.1002/jrs.1250241210

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe Raman spectrum of deuterated piperazine hexahydrate shows a new band that is red shifted from the main ND stretch by 38 cm−1. The intensity of this band increases at low temperatures. It is proposed that this band arises from polarons. Although the corresponding new band is not resolved in the NH stretch region of the hydrogenated system, the band width increases on cooling, which suggests the appearance of a new band due to polarons. The less resolved spectral feature in the hydrogenated system is disc

ISSN:0377-0486    

DOI:10.1002/jrs.1250241211

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY