摘要:

AbstractThe Raman (3200 to 10 cm−1) and far‐infrared (375 to 80 cm−1) spectra of gaseous bromocyclobutane, c‐C4H7Br, have been recorded. A series ofQ‐branches observed in both of these spectra, beginning at 149 cm−1with successive transitions falling to lower frequencies, have been assigned to the ring‐puckering vibrations of both the low‐energy equatorial and high‐energy axial conformers. These data have been fit to an asymmetric potential function of the formV(cm−1) = (6.58 ± 0.21) × 105X4− (3.27 ± 0.04) × 104X2× (4.59 ± 0.19) × 104X3with a reduced mass of 214 amu. Utilizing this potential, the difference between the puckering angles for the two conformers is calculated to be 6°, with the equatorial conformer having the larger value of 20°. Also from this potential function, the energy difference between the equatorial and axial forms is found to be 361 ± 20 cm−1(1.03 kcal mol−1), with a barrier of 636 ± 20 cm−1(1.82 kcal mol−1) to interconversion. Experimental values for the enthalpy difference between the two conformers have been determined for both the liquid (297 ± 27 cm−1) and gas (∼ 350 cm−1) from relative intensities of a pair of Raman lines over 90 and 58 °C temperature ranges respectively. These results are compared to the cor

ISSN:0377-0486    

DOI:10.1002/jrs.1250201202

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractA detailed study of the NH2(ND2) modes of benzocaine is reported. The Raman spectra in the solid state and in chloroform solution between 200 and 4000 cm−1were studied and a tentative assignment is proposed. The torsional barriers of the amine groups were calculated using several methods. The determination of the theoretical torsional frequencies was carried out according to the CNDO/2 method, using a Harmonic approximation and a Hamiltonian calculatio

ISSN:0377-0486    

DOI:10.1002/jrs.1250201203

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe Raman spectra of NiCl2· 6H2O, NiBr2· 6H2O and FeCl2· 4H2O single crystals were measured in the range 50–3600 cm−1at liquid nitrogen temperature. A new assignment of the lattice water translations in the two hexahydrates was made and the metal‐halogen stretching mode was identified. A comparison with recent IR data provided a good characterization of the water libration region. Some proposals for discriminating between the lattice water modes and the coordinated water modes are given for the water internal modes (bending and str

ISSN:0377-0486    

DOI:10.1002/jrs.1250201204

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe temperature dependence of the isotropic and anisotropic Raman components for the H2O and D2O stretching vibrations has been studied. The results of resolution of the isotropic component into three constituents and the anisotropic into four constituents are compared with the values calculated by the perturbation method for a superposition of the Fermi and intermolecular coupling resonances. The experimental results were found to agree qualitatively with the predicted values.

ISSN:0377-0486    

DOI:10.1002/jrs.1250201205

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractAn index matching technique for Raman scattering from sapphire fibers is presented; the technique is shown to be effective in suppressing the stray laser background and leads to an improved signal‐to‐noise ratio of the Raman signal. Red shifts of phonon frequencies for bothA1gandEgsymmetry modes were observed under tensile uniaxial stress parallel to thecaxis. The unexpected shifts of theEgmodes may be attributable to effects due to restricted dimensi

ISSN:0377-0486    

DOI:10.1002/jrs.1250201206

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractRaman and far‐infrared spectra of crystalline formaldehyde and its fully deuterated analogue have been recorded over the frequency range 25–350 cm−1and at temperatures of 80 and 20 K; 16 Raman and 8 far‐infrared lattice peaks have been resolved. Isotopic frequency shifts together with inertia and intensity arguments are used to assign the peaks. Raman spectra of the internal vibrational modes of solid formaldehyde are also presented, with several crystal field splittings observed. The results are consistent with a group theoretical analysis based on the molecular and crystal sym

ISSN:0377-0486    

DOI:10.1002/jrs.1250201207

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe vibrational spectra ofn‐octyl‐3,4:9, 10‐perylenetetracarboxylic monoanhydride (Oc‐PTCDO) and ofn‐octyl‐3,4:9,10‐perylenetetracarboxylic monoimide (Oc‐PTCDNH) have been studied. Langmuir‐Blodgett (LB) films of both dye pigments were prepared and transferred to glass slides and silver surfaces for spectroscopic characterization. Using mixed LB monolayers of Oc‐PTCDNH and arachidic acid, the surface‐enhanced fluorescence of the monomer and aggrega

ISSN:0377-0486    

DOI:10.1002/jrs.1250201208

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractA study of the Raman, pre‐resonance Raman and electronic spectra of the [VO(C3H2O4)2]2−anion was performed. The excitation profiles of the vibrational modes that show pre‐resonance on excitation with laser lines within the electronic bands in the visible region are reported. On this basis, the VOmalon. vibrations could be unambiguously assigned and stronger experimental support is provided for the origin of some of the electronic tran

ISSN:0377-0486    

DOI:10.1002/jrs.1250201209

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThere is renewed interest in stimulated Raman scattering in organic liquids because of its potential for droplet sizing in fuel sprays. Contrary to the accepted theories, we observed gain on more than one line simultaneously. In all but the simplest aromatics multiple lines are observed and some expected lines are missing. Absorption spectra suggest that two‐photon absorption could quench the expected Raman signal. A model using real values of two photon cross‐sections shows that in polyaromatics, these are a source loss term for the Raman signal. The resulting disperion in the loss profile leads to gain on the CH stretch rather than the ring breathing mode predicted from the spontaneous spe

ISSN:0377-0486    

DOI:10.1002/jrs.1250201210

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractLaser‐excited emission from YBa2Cu3O7–δwith 7.5% dysprosium nominally subsituted in place of yttrium is presented in the range 13 000–23 000 cm−1. In addition to the reported Raman lines in the CuO stretching region, a number of other spectral features were observed. These include a discrete luminescence with lines at 14 400 and 14 425 cm−1and a broad emission with its peak position and band width varying with excitation wavelength. Additionally, an anti‐Stokes scattering, which has no apparent counterpart in the Stokes region, was observed. These observations may be of significance in the elucidation of the mechanism of high‐temperature s

ISSN:0377-0486    

DOI:10.1002/jrs.1250201211

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY