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1.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1989,45(2):305-313
Raman and i.r. spectra of tetramethylcyclobutane-1-one-3-thione (TMCBOT) and the fully deuterated derivative TMCBOT-d12 have been recorded. A fairly complete set of vibrational frequencies and assignments are given for the two molecules. The CO stretching mode was observed as a very strong Fermi doublet in the infrared spectrum of TMCBOT at 1811/1782 cm−1. For TMCBOT-d12 a similar doublet was observed at 1808/1775 cm−1. The CS stretching mode was assigned to bands at 1303 cm−1 for TMCBOT and 1307 cm−1 for the deuterated molecule. 相似文献
2.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1981,37(8):639-642
Raman spectra of pivalic acid in the plastic and liquid phase have been measured. The reorientational correlation times have been evaluated from the νasCH, νCO and νCC bands as a function of temperature. The reorientational correlation time corresponding to νas CH and νCC bands is τ < 10−11 s whilst for the νCO band τ = 4ps (T = 20°C). The calculated activation energy is 26 KJ mol−1. The reorientation of the carboxylic groups which may be assisted by the proton transfer along the hydrogen bonds in dimers is discussed. 相似文献
3.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1991,47(9-10):1431-1440
1064-nm-excited Fourier transform Raman spectra of bacteriochlorophyll-a (BChl) in various solid films and in chromatophores from a blue-green mutant of Rhodobacter sphaeroides have been obtained. The observed Raman spectra are free from high fluorescence backgrounds and sample degradation. The observed intensities seem to be enhanced because of a pre-resonant effect between the exciting radiation at 1064 nm and the Qy absorption at 770–870 nm of BChl. The spectral features are substantially different from the Soret and Qx resonance Raman spectra extensively investigated so far; several bands in the wavenumber region lower than 1200 cm−1 are particularly enhanced in the Qy pre-resonance Raman spectra. Bands due to both the C2O and C9O stretches appear at 1700–1620 cm−1, providing structural information on these carbonyl groups. In the CC stretching region (1620–1490 cm−1), the correlation between band positions and the co-ordination number of central magnesium, which was previously found in the Soret-excited Raman spectra, is preserved in the Qy, pre-resonance Raman spectra as well. The relative intensities of strong bands in the 1200–1000 cm−1 region appear to be useful for characterizing the BChl state. By using these advantages of the Qy, pre-resonance Raman spectra, molecular interactions and arrangements of BChl in hydrated films and in the B870 light-harvesting complex of R. sphaeroides are discussed. 相似文献
4.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1989,45(2):207-211
Infrared and Raman spectra of KHFur 2,3 and KDFur 2,3 are presented. An assignment of the bands is given which is in good agreement with previous results concerning acid salts possessing intramolecular hydrogen bonds. The νas OHO participation was observed at 670 and 520 cm−1, absorption bands of medium intensity. The absence of a more pronounced broadening might be explained by assuming an anharmonic coupling between the νas OHO and the νs OHO modes, resulting in a combination band at 1000 cm−1. 相似文献
5.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1979,35(11):1265-1276
The i.r. and Raman spectra of the trans-enol form of some β-diketones and their deuterated analogues in α position are examined in the 4000-50cm−1 range and an approximate assignment is given for the fundamental vibrations. The νas(OH) and ν(CO) values suggest that the intramolecular H-bond strength increases in the order: hexafluoroacetylacetone < trifluoroacetylacetone < acetylacetone < α - Cl - acetylacetone < benzoylacetone < dibenzoylmethane < tetraacetylethane.The observed relative Raman intensities of the ν(CC) and ν(CC) bands also support this feature. The spectroscopic results show a great change in the internal modes of the β-diketones upon deuteration; this behaviour indicates a greater localization of the π-electron system of the chelate ring and a weakening of the H-bond on deuteration. The νs(OH) vibration seems to be involved in one of the in-plane ring deformational modes. 相似文献
6.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1981,37(3):177-181
The following zinc (II), cadmium (II) and mercury (II) complexes of 2-methyl-benzoxazole (L) have been prepared and studied by conductometric and i.r. methods: MLX2 (MCd, XCl, Br; MHg, XCl), HgL1.5X2 (XBr, ClO4), ML2X2 (MZn, XCl, Br, I, NO3; MCd, Hg, XI, NO3), ZnL3(ClO4)2·2H2O, CdL3(ClO4)2·3H2O. The frequency decrease of the ligand bands at 1614 and 1573 cm−1 having a ν(CN) and the increase of the ligand band at 918 cm−1 having a ν(CO) contribution indicate that in the complexes the ligand is N-bonded to the metal. 相似文献
7.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1989,45(12):1305-1312
Interactions between perfluoro-t-butanol (PFTB) and acetonitrile-d3 (AN) in a mixture of freons are studied between 298 and 88 K in liquid or vitreous states. In the conditions of the experiment, a mean 1:2 stoichiometry [PFTB⋯(AN)2] is inferred from previous matrix measurements. A νOH shift of about 160 cm−1 is observed in this temperature range: it is mainly ascribed to solvent effects on the complex. In fact, the dνOH/dT coefficient increases at low temperature on account of specific solvation of the complex by the freon Br atoms. The νOH + τOH combination wavenumber is little dependent on the state of PFTB, near 3900 cm−1. A comparatively strong simultaneous transition involving the PFTB νOH mode and a νCN mode of neighbouring AN molecules is observed. Weaker bands could also be explained by such transitions involving a combination level of PFTB and a νCN vibration. Strong Fermi resonances are displayed in the 2νOH region when the νOH band is located around 3100 cm−1, either in pure AN or in freons at low temperature. The levels interacting with 2νOH are ternary combinations and quaternary overtones mainly involving the COH bend and the CO stretch. These resonances are favoured by a strong increase of the OH stretching vibration anharmonicity. 相似文献
8.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1988,44(6):553-565
The infrared spectrum of CHF2Cl has been recorded between 15 000 and 350 cm−1. The Fermi resonance between levels involving ν4 and 2ν6 is analysed in bands extending from 800 cm−1 to 7000 cm−1 leading to a best value of k466 = ± 14.98 cm−1. In conjunction with the recent results of Amrein, Dubal and Quack, Molec. Phys. 56,727 (1985); estimates are reported for 38 out of 45 possible xij constants. A variation in the relative intensity of the two Q branches associated with ν1, on cooling the gas cell, indicates that a hot band contributes to the upper branch at 3024.55 cm−1. However, other evidence suggests that the latter arises also from the combination ν2 + ν7 + ν9, in a very weak, close resonance with ν1 at 3021.27 cm−. A number of anomalous band contours are reported. 相似文献
9.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1987,43(5):657-673
The i.r. (4000-40 cm−1) and Raman (4000-10 cm−1) spectra of gaseous, liquid and solid methoxy difluorophosphinoxide, CH3OP(O)F2, and the deuterated analog have been recorded. Results obtained from variable solvent and matrix isolation studies are consistent with the existence of both trans (CO bond trans to the PO bond) and gauche (dihedral angle approximately 120° from the trans form) conformers in the fluid phases. From simulations of observed gas phase i.r. band profiles, it was possible for assignments to be made to the individual conformers for a number of the fundamentals. Variable temperature studies carried out for the gaseous and liquid phases give energy differences between the gauche and trans conformers of 451 ± 100 cm−1 (1.29 ± 0.3 kcal/mol) and 69 ± 20 cm−1 (197 ± 57 cal/mol), respectively. Furthermore, these data are consistent with the gauche form being the thermodynamically preferred conformer for the gas phase whereas the trans conformer is preferred in the liquid phase and the only conformer present in the annealed solid. The methoxy torsional mode of the gauche conformer has been assigned to a very strong band observed in the far i.r. spectrum of the gas phase at 42 cm−1. The matrix isolation spectra of the normal compound in Ar, CO and N2 matrices indicated no changes in the conformational equilibrium among these different matrices and this equilibrium remains unchanged upon annealing the matrices. 相似文献
10.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1993,49(7):953-964
The structures and force field of 1,3,5,7-cyclooctatetraene (COT) have been studied using ab initio theory at the SCF level with the 4-21G basis set. The quadratic force field of the D2d structure obtained by systematic scaling of the ab initio force constants successfully reproduces the observed frequencies of COT and COT-d8 with a mean deviation of less than 10 cm−1 for non-CH stretching modes. On the basis of the calculated results, assignments of the fundamental vibrations are examined. The normal mode υ5 is reassigned to a weak band at 758 cm−1 in the Raman spectrum of COT and to a weak band at 591 cm−1 in the Raman spectrum of COT-d8. The calculations favor the assignment of υ26 given by Lippincott et al. [J. Am. Chem. Soc. 73, 3370 (1951)] over the revised assignment of Perec [Spectrochim. Acta 47A, 799 (1991)]. The calculations also furnish reliable prediction for the inactive A2 fundamentals of COT and COT-d8. The fundamental frequencies and IR and Raman intensities of 13CC7H8, which constitutes about 9% of COT in natural abundance, are also calculated. Only ν10 (calculated at 908 cm−1) of the formal inactive A2 modes has appreciable Raman intensity (0.23 Å4/amu). A spectral feature due to this fundametal is identified in the liquid Raman spectrum of Tabacik and Blaise [C. R. Acad. Sci. Ser. II 303, 539 (1986)] as a weak peak at 908 cm−1. 相似文献
11.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1979,35(9):1029-1032
Infrared and Raman spectra in the liquid state of 3-R, 4-X cyclohexenes (R = CH3, (CH3)3C; X = CN,Cl) and their d1-(4) and d3-(3,6,6) isotopic modifications, Raman spectra of some low temperature crystallised compounds, vibrational spectra in the solid state of cis and trans 1-acetoxy 3-t-butyl 4-cyano cyclohexenes, were studied.The frequencies of cyclohexenic skeleton modes below 900 cm−1 and the frequencies of deformation modes involving the CCN bond or stretching νCCl vibration of the different conformers were assigned. In the cis and trans 1-acetoxy 3-R 4-cyano cyclohexenes (respectively in the e′a and e′e conformations), the positions of the 627 cm−1 δax and the 538 cm−1 δeq deformation vibrations agree with the assignments proposed for the other cyano derivatives. 相似文献
12.
《Journal of Molecular Structure》1987,157(4):371-384
Spectroscopic investigation of 5-chloro-2-pyridone has been carried out in the temperature range 77–300 K. At room temperature the 35Cl NQR spectrum shows a single line at 35.618 MHz, but at 250.7 K two lines appear at 35.850 MHz and 35.840 MHz respectively indicating the presence of a phase transition. IR, far-IR, laser Raman and dielectric measurements have been carried out to investigate the phase transition further. Low temperature IR studies show splitting of ν(CCl), β(NH) and ν(CO) bands at Tc. Dielectric measurements show a small, but finite, change in the value of the dielectric constant around Tc. Raman spectra at different temperatures support the existence of a new phase, as shown by the appearance of a new band at 81 cm−1, the frequency of which changes slowly as Tc is approached and which disappears at Tc. The temperature dependence of the NQR frequencies has been analysed using Bayer Kushida and Brown equations toevaluate the torsional frequencies. 相似文献
13.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1993,49(11):1683-1684
The solid state IR and Raman spectra of SnPh3Br do not show any band at 338 cm−1, and there is not C3ν point group inversion between νas SnC3 and νs SnC3 for SnPh3X (X Cl, Br). The presence or absence of a band around 338 cm−1 in the IR spectra of triphenyltin compounds cannot be used to distinguish between pyramidal and planar SnPh3 groups. 相似文献
14.
Infrared transmission,attenuated total reflectance,and Raman spectra of potassium hydrogen succinate
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1977,33(8):735-744
The nature of the broad and strong absorption culminating near 950 m−1 and of the bands in the 1600–1700 cm−1 region is discussed with respect to polarized transmission, ATR, and Raman data obtained with single crystals of potassium hydrogen (and deuterium) succinate. The former absorption seems to be due to the Bu type OHO stretching combined with multiphononic components arising from transitions between the ν OHO and σ OHO branches for k ≠ 0. These appear to activate also the CO modes not allowed in the harmonic approximation for the C2h factor group. Assignments for other bands are also given. 相似文献
15.
This research was done on hureaulite samples from the Cigana claim, a lithium bearing pegmatite with triphylite and spodumene. The mine is located in Conselheiro Pena, east of Minas Gerais. Chemical analysis was carried out by Electron Microprobe analysis and indicated a manganese rich phase with partial substitution of iron. The calculated chemical formula of the studied sample is: (Mn3.23, Fe1.04, Ca0.19, Mg0.13)(PO4)2.7(HPO4)2.6(OH)4.78. The Raman spectrum of hureaulite is dominated by an intense sharp band at 959 cm−1 assigned to PO stretching vibrations of HPO42− units. The Raman band at 989 cm−1 is assigned to the PO43− stretching vibration. Raman bands at 1007, 1024, 1047, and 1083 cm−1 are attributed to both the HOP and PO antisymmetric stretching vibrations of HPO42− and PO43− units. A set of Raman bands at 531, 543, 564 and 582 cm−1 are assigned to the ν4 bending modes of the HPO42− and PO43− units. Raman bands observed at 414, and 455 cm−1 are attributed to the ν2 HPO42− and PO43− units. The intense A series of Raman and infrared bands in the OH stretching region are assigned to water stretching vibrations. Based upon the position of these bands hydrogen bond distances are calculated. Hydrogen bond distances are short indicating very strong hydrogen bonding in the hureaulite structure. A combination of Raman and infrared spectroscopy enabled aspects of the molecular structure of the mineral hureaulite to be understood. 相似文献
16.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1976,32(9):1563-1569
The ν1 spectrum of HCCCl was studied at a resolution of 0.045 cm−1. Six bands were assigned and analyzed, two for the Cl37 and four for the Cl35 isotope. Band constants obtained for the six bands are listed. The ν1 + ν5 ← ν5 band is unusually intense on the P side. 相似文献
17.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1981,37(8):615-626
The rovibrational spectra of CF379Br and CF381Br in the region of ν2+ν3 near 1120 cm−1 and ν1+ν2+ν3 near 2200 cm−1 have been investigated with a resolution of 0.04 and 0.03 cm−1 respectively. The rotational J structures have been resolved and were analyzed by means of polynomial and band contour simulation procedures. Molecular parameters (ν0, xij, αA,B) have been obtained from the analysis of the cold bands and the hot bands involving ν6, 2ν6, ν3 and ν5 for both isotopomers. 相似文献
18.
《Vibrational Spectroscopy》2002,28(2):209-221
Syngenite (K2Ca(SO4)2·H2O), formed during treatment of manure with sulphuric acid, was studied by infrared, near-infrared (NIR) and Raman spectroscopy. Cs site symmetry was determined for the two sulphate groups in syngenite (P21/m), so all bands are both infrared and Raman active. The split ν1 (two Raman+two infrared bands) was observed at 981 and 1000 cm−1. The split ν2 (four Raman+four infrared bands) was observed in the Raman spectrum at 424, 441, 471 and 491 cm−1. In the infrared spectrum, only one band was observed at 439 cm−1. From the split ν3 (six Raman+six infrared) bands three 298 K Raman bands were observed at 1117, 1138 and 1166 cm−1. Cooling to 77 K resulted in four bands at 1119, 1136, 1144 and 1167 cm−1. In the infrared spectrum, five bands were observed at 1110, 1125, 1136, 1148 and 1193 cm−1. From the split ν4 (six infrared+six Raman bands) four bands were observed in the infrared spectrum at 604, 617, 644 and 657 cm−1. The 298 K Raman spectrum showed one band at 641 cm−1, while at 77 K four bands were observed at 607, 621, 634 and 643 cm−1. Crystal water is observed in the infrared spectrum by the OH-liberation mode at 754 cm−1, OH-bending mode at 1631 cm−1, OH-stretching modes at 3248 (symmetric) and 3377 cm−1 (antisymmetric) and a combination band at 3510 cm−1 of the H-bonded OH-mode plus the OH-stretching mode. The near-infrared spectrum gave information about the crystal water resulting in overtone and combination bands of OH-liberation, OH-bending and OH-stretching modes. 相似文献
19.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1980,36(2):171-176
The i.r. spectrum of gaseous CF3Cl has been recorded in the ν4 region near 1200 cm−1 with a resolution of 0.08 cm−1. The rovibrational band system has been analyzed by means of band contour simulation. It is shown that the irregular structure of the R branch arises from the two components of ν4 + ν6 - ν6. A general theoretical treatment for hot bands νi + νj - νj is given where νi and νj belong to E species of point group C3ν. 相似文献
20.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1994,50(8-9):1467-1473
The resonance Raman spectra of all-trans carotenoids have been observed in the region of 5000-500 cm−1 for samples in glassy solution at 77 K and in the in vivo state at room temperature. Prominent bands in the wavenumber region higher than 2000 cm−1 are assigned to either overtones or combinations of three modes due to skeletal stretches and the CH3 in-plane rock. From the wavenumbers of the observed Raman bands, anharmonicity constants for these three modes (including cross-term constants) are obtained. It is found that, for each carotenoid studied, the cross-term anharmonicity constant between the CC and CC stretches is significantly larger than the other anharmonicity constants. 相似文献