摘要:

AbstractWe have used vibrational Raman spectroscopy to study the chemisorption of carbon monoxide and of ethylene, and the chemical interactions of coadsorbed carbon monoxide and hydrogen on silica‐supported nickel particles. In each case we observe a strong enhancement of all measured vibrational bands which depends on the excitation wavelength. The maximum enhancement lies always in the excitation wavelength range 5200–4500 Å. The enhancement is of the order 102−104. The complex spectra from coadsorbed CO and H2indicate the formation of several surface species: adsorbed carbon monoxide, hydrocarbon‐like species, and different oxygen‐containing hydrocarbon compounds. A complete assignment of all vibrational bands is not possible because of the complexity of the Ram

ISSN:0377-0486    

DOI:10.1002/jrs.1250110602

出版商:John Wiley&Sons, Ltd.    

年代:1981

数据来源: WILEY

摘要:

AbstractDimethylsulphoxide (DMSO)‐hydrogen chloride interactions have been studied by means of Raman and infrared spectroscopy both in solid 1:1 adducts and in liquid mixtures with DMSO:HCl molar ratios>2. The deuterated analogue solid 1:1 (DMSO‐d6)‐DCl was also prepared and studied. Vibrational data suggest the presence of a (DMSOHOSMD)+cation with strong (OHO)+hydrogen bonds both in the solid adducts and in the liquid mixtures. In the solid adducts the (CIHCl)−anion may be present. A relation between some biological properties of DMSO and its protonation i

ISSN:0377-0486    

DOI:10.1002/jrs.1250110603

出版商:John Wiley&Sons, Ltd.    

年代:1981

数据来源: WILEY

摘要:

AbstractThe Raman line shapes of three symmetric modes ν1, ν3and ν4have been measured in liquid dichloromethane as a function of pressure from 1 bar to 3 kbar and of temperature from 183 to 363 K. The reorientation relaxation times are found to increase with higher pressures and to decrease with increasing temperatures. The isotropic half‐width of the ν4band behaves untypically, varying only insignificantly throughout the temperature and pressure range studied. The differences in frequency between the polarized and depolarized bands are also determined. The dipolar coupling mechanism is applied to interpret the effects obs

ISSN:0377-0486    

DOI:10.1002/jrs.1250110604

出版商:John Wiley&Sons, Ltd.    

年代:1981

数据来源: WILEY

摘要:

AbstractAn experimental method for the determination by Raman spectroscopy of the composition of a gas mixture in which a chemical equilibrium occurs, and the related processing of the data are discussed. Acetic acid vapour, for which none of the components of the equilibrium can be isolated, is chosen as an example. The intensities of the ν(CC) bands are taken as monitors for the concentrations of monomer and dimer species. The mixture has been studied at 120°C and 155°C, in the pressure ofc. 0.2–1.5 atm. Using gas density data, a treatment in terms of molal concentrations leads to consistent results, the ratio of Raman scattering cross‐sections at the wavenumbers corresponding to the ν(CC) vibrations (dimer/monomer) being found the same for both isotherms and equal to 1.64. The other significant results are:Kc app= 0.48 atm. at 120°C and 2.67 atm. at 155°C. ΔH(dissociation of one mole of dimer) = 16.3 kcal (range 120–155°C). An alternative treatment in which an ideal behaviour of the gas phase is assumed shows that Raman measurements are accurate enough to emphasize the inadequacy of this approximation in the temperature and pressure range considered. The Raman spectrum of gaseous acetic acid (range 100–3700 cm−1) at ∼220°C

ISSN:0377-0486    

DOI:10.1002/jrs.1250110605

出版商:John Wiley&Sons, Ltd.    

年代:1981

数据来源: WILEY

摘要:

AbstractThe relative intensities of bands in a polarized Raman Lattice spectrum ofp‐chloroaniline are interpreted in terms of the oriented gas model. Among different reasons for deviations from this model the vibronic intensity enhancement ofB1gandB3glattice bands has been found to be the most important on

ISSN:0377-0486    

DOI:10.1002/jrs.1250110606

出版商:John Wiley&Sons, Ltd.    

年代:1981

数据来源: WILEY

摘要:

AbstractRaman spectroscopy has been used to characterize various MoO3/γ‐Al2O3and CoO (or NiO)‐MoO3/γ‐Al2O3catalysts containing 12 wt% MoO3and 3 wt% CoO (or NiO) prepared by different methods. No significant differences between samples prepared by the wet impregnation and the pore volume method could be observed in molybdena‐supported catalysts; in these samples the majority of Mo is present as isolated distorted MoO42−tetrahedra due probably to a low coverage of the alumina surface (SBET=240 m2g−1). Addition of NiO to the molybdena‐supported catalysts seems to cause only a slight increase in the distortion and interaction between MoO42−species. In contrast, CoO addition to the molybdena‐supported catalysts changes considerably the spectra features, suggesting that the Mo species are highly distorted, presumably in different surroundings on the alumina surface, due to the strong interaction of Co with Mo species. However, simultaneous impregnation of both MoO3and CoO or NiO results in a more regular arrangement of Mo species and an increase in formation of polymeric Mo species, particularly with Co‐containing catalyst, where a relative higher degree of polymeric

ISSN:0377-0486    

DOI:10.1002/jrs.1250110607

出版商:John Wiley&Sons, Ltd.    

年代:1981

数据来源: WILEY

摘要:

AbstractThe Raman spectra of gaseous, liquid and solid trimethylgermylazide, (CH3)3GeNNN, and the infrared spectra of the gas and solid have been recorded (20–3200 cm−1). Assignment of the fundamentals, based on their depolarization values and group frequencies, is given and discussed. A normal coordinate calculation has been carried out utilizing a modified simple valence force field. The extent of vibrational coupling has been determined. It is believed that the main force constants should be transferable to other substituted trimethylgermanium compounds and, thus, transferability is demonstrated by some normal coordinate calculations for trimethylgermylisocyanate and trimethylgermylisothiocyanate. The bonding in these pseudohalogens is discussed and it is shown that the appropriate resonance structures can account for the linearity of the GeNCS moiety and the non‐linearity of the GeNCO and GeNNN moi

ISSN:0377-0486    

DOI:10.1002/jrs.1250110608

出版商:John Wiley&Sons, Ltd.    

年代:1981

数据来源: WILEY

摘要:

AbstractThe infrared (4000–80 cm−1) and Raman (3500–10 cm−1) spectra of (CH3)3GaO(CH3)2and (CH3)3GaO(CD3)2have been recorded for the solid state at 77 K. The Raman spectra of the liquids have also been recorded and depolarization values measured. The spectra have been interpreted in detail on the basis ofCsmolecular symmetry. The valence force field model has been utilized in calculating the frequencies and potential energy distribution for the heavy atom skeleton. Considerable coupling has been observed among the OC2bending motions and the GaC3bending modes. The GaO stretch could not be assigned to a particular low frequency band, but this motion contributed significantly to four different bands ranging in frequency from 279 to 148 cm−1. The calculated force constants for the adducts are compared to those previously reported for the Lewis base moiety and the differences are shown to be consistent with structural changes expected upon adduc

ISSN:0377-0486    

DOI:10.1002/jrs.1250110609

出版商:John Wiley&Sons, Ltd.    

年代:1981

数据来源: WILEY

摘要:

AbstractRaman spectra of crystalline pentachloroaniline (PCA) have been measured. The infrared spectra have also been recorded for solid and solutions in CCl4between 4000–200 cm−1. An assignment of the observed frequencies has been proposed for aCsmolecular symmetry based on related halogen substituted benzene derivatives. The molecule does not appear to self‐associate in CCl4solutions although there is some evidence for a weak hydrogen bonding in the solid

ISSN:0377-0486    

DOI:10.1002/jrs.1250110610

出版商:John Wiley&Sons, Ltd.    

年代:1981

数据来源: WILEY

摘要:

AbstractThe Raman and infrared spectra of polycrystalline samples of 9‐methyladenine and three of its methylmercury complexes have been recorded. These complexes include the N1‐coordinated and the N1‐coordinated‐NH2‐substituted derivatives, the third compound being probably N1‐and N7‐coordinated. Spectral changes occurring upon complexation are analysed, and comparisons are made with the corresponding changes in the spectra of various adenine derivatives which are known to form complexes with CH3Hg+in aqu

ISSN:0377-0486    

DOI:10.1002/jrs.1250110611

出版商:John Wiley&Sons, Ltd.    

年代:1981

数据来源: WILEY