摘要:

AbstractRaman‐induced Kerr effect spectroscopy (RIKES) as a tool for the investigation of species in solution is presented. RIKES has proved to be a particularly useful probe for Raman modes of molecules in solution because control of the polarizations of the interacting laser fields allows non‐resonant solvent contributions to the background to be minimized. New techniques to subtract laser power fluctuations from the signal have further increased the sensitivity of RIKES. Spectra of carbon tetrachloride, benzene and the hydroxide ion are presented to show the utility of RIKES for investigating solutions. The ability to decrease background noise by controlling the polarization of the pump laser was demonstrated by studying the 459 cm−1carbon tetrachloride resonance. Concentration studies on benzene in carbon tetrachloride showed a narrowing of the 992 cm−1mode of benzene as its concentration was decreased. The sensitivity of the technique is demonstrated with spectra recorded on 0.01Mbenzene in carbon tetrachloride. The 3620 cm−1OH−resonance is presented for a 10Msolution of NaOH in water. A nearby water resonance makes the OH−mode difficult to see at lower concentrations. Polarization tuning was not able to improve the RIKES sensitivity

ISSN:0377-0486    

DOI:10.1002/jrs.1250200402

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractModel calculations are reported aimed at interpreting the Raman excitation profiles observed by Lichtmannet al. They refine earlier calculations by Siebrand and Zgierski based on displaced harmonic oscillators. A distribution of conjugation lengths is introduced and the dependence of the model parameters, in particular the resonant state energy, on this length is investigated. This, together with an allowance for vibrational frequency changes and non‐Condon effects, yields a much improved fit to the observed profiles. The results suggest a narrow distribution of relatively short conjugation lengths (⩽20 double bonds), contrary to most earlier reported distributions based on the dispersion of Raman bands, but comparable to a distribution based on isomerization kinet

ISSN:0377-0486    

DOI:10.1002/jrs.1250200403

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractL'étude Raman des verres de la série 0.2Na2O(0.8 −x)SiO2xB2O3a été réalisée pour des pourcentages molairesxen B2O3tels que 0

ISSN:0377-0486    

DOI:10.1002/jrs.1250200404

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractLow‐frequency Raman spectra of liquids on both Stokes and anti‐Stokes sides were investigated. The spectra are given in theR(v̄) representation. Results for a pure and an impure sample of fluorobenzene were compared. The results allow a distinction between the effects of stray light and fluorescence in the spectra. The same method was used for liquid water at temperatures ranging from the freezing point to 40°C. The background correction for Raman spectra in theR(v̄) representation is discussed. This procedure is of special importance for aqueous solutions of biologically interesting molecules. The use of the anti‐Stokes side is an advantage, as demonstrated byR(v̄) spectra of an aqueous solution of L‐as

ISSN:0377-0486    

DOI:10.1002/jrs.1250200405

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe efficiency of Raman microscopy coupled with multichannel acquisition of data was tested for studying the dissolution layer of a mineral salt in its undersaturated mother solution. Experimental work was carried out on sodium nitrate solutions at concentrations ranging between 0.05 and 7.8M. At lower concentrations the existence of three main species, free aquated ions, solvent‐separated ion pairs and contact ion pairs, was confirmed spectroscopically, in addition to a small amount of aggregates (NO3−· Na+)nwhich occur only at high concentrations ([NO3−]>2M). Gaussian‐Lorentzian parameters of each ν1(A′1) band characteristic of such individual species were calculated and were found to vary considerably depending on whether the Raman spectra were recorded with a standard scanning system or with a multichannel detector. When the laser beam was focused at the interface between a dissolving NaNO3crystal and the sodium nitrate solution ([NO3−]=4.68M), the micro‐Raman spectra showed that the concentration of aggregates was considerably increased compared with that determined in the same way in the bulk of the nitrate solution. The technique used to obtain reliable spectra of the dissolution layer is disc

ISSN:0377-0486    

DOI:10.1002/jrs.1250200406

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractRaman spectra ofp‐cresol, a model compound for tyrosine, were measured in solutions of various solvents, paying special attention to the effects of hydrogen bonding on the Raman bands in the 1300–1150 cm−1region. The frequency of the ν7a(CO stretch) band was found to be sensitive to the state of hydrogen bonding at the phenolic hydroxyl group. It occurs at 1275–1265 cm−1in proton‐donating states, 1240–1230 cm−1in proton‐accepting states and around 1255 cm−1in weakly or non‐hydrogen‐bonding states. This relationship between the ν7a′frequency and hydrogen bonding was verified in the Raman spectra of L‐tyrosine and its derivatives in the crystalline state. Analysis of the crystal Raman spectra further suggested that the ν7a(CC stretch) frequency also serves as a marker, though less sensitive, of hydrogen bonding and the ν9a(CH bend) frequency reflects the displacement of the OH hydrogen atom from the plane of benzene ring, which may be induced by hydrogen bonding. These Raman bands are strong with UV excitation and are expected to be useful in characterizing tyrosine side‐chains in peptides and prot

ISSN:0377-0486    

DOI:10.1002/jrs.1250200407

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe Raman and IR spectra of chloro‐ and bromo‐cyclobutane as vapours, liquids and as amorphous and crystalline solids were recorded at various temperatures. Additional IR spectra of the high‐pressure crystalline phases were obtained at ca 25 kbar pressure. IR matrix isolation spectra were recorded at 14 K, using the hot nozzle technique.Evidence is presented to show that chloro‐ and bromo‐cyclobutane have a second (axial) conformer existing in amounts less than 10% for chloro‐ and 3% for bromo‐cyclobutane at ambient temperature, in addition to the dominant (equatorial) conformer. From the study of the Raman spectra of the liquid and vapour as a function of temperature, enthalpy differences between the two conformers were calculated. The axial conformers could not be trapped at 17 K, revealing the barrier to ring conversion to be smaller than 5 kJ mol−1.New vibrational assignments, supported by normal coordinate analyses are presented for

ISSN:0377-0486    

DOI:10.1002/jrs.1250200408

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractN‐Alkylurotropinium polyiodides, UrRIx, with different iodine contents and different sizes of alkyl group were investigated by Raman spectroscopy. The spectra were recorded for wavenumber shifts up to 500 cm−1. It was found that the triiodides, UrRI3, contain a symmetrical linear I3−ion. The pentaiodides, UrRI5, contain no triiodide unit; the anion structure can be described as nearly symmetrical, rectangular L‐shaped I5−. An interpretation of the Raman spectra of the heptaiodides, UrRI7, is that the anion corresponds to an I5−. I2structure. This is the first proof of such a heptaiodide. A review of previously published data on the Raman spectra of polyiodides is

ISSN:0377-0486    

DOI:10.1002/jrs.1250200409

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe Raman spectra of polymerized tetra‐n‐butoxy titanate [pol‐Ti(OBu)4] formed on the surface of five different types of silica gel were studied. Characteristic peaks were found in the range 1000‐1200 cm−1in all the spectra. The observed Raman spectra showed that the network structure of pol‐Ti(OBu)4formed on the surface of silica gels, that is, the TiOTiO chain, seems to depend on the properties of the pores of the silica gels. The butoxy groups might be located in a state with a different degree of order. On the other hand, the catalysts which were prepared by using pol‐Ti(OBu)4showed different ph

ISSN:0377-0486    

DOI:10.1002/jrs.1250200410

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe infrared and Raman spectra ofp‐nitrobenzaldehyde were recorded on a Perkin‐Elmer IR 983 double‐beam grating spectrophotometer and on a Cary Model 82 grating spectrophotometer, respectively. The observed frequencies were assigned to various modes of vibrations on the basis of normal coordinate calcula

ISSN:0377-0486    

DOI:10.1002/jrs.1250200411

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY