ISSN:0377-0486    

DOI:10.1002/jrs.1250220302

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractAn application of time‐dependent theory to continuum resonance Raman scattering in79Br2is described. Calculated profiles and spectra are compared with traditional time‐independent results and experimental spectra from the literature. Similarities and differences between the time‐dependent and time‐independent methods from their theoretical derivation through different stages of results up to their explanatory power are ev

ISSN:0377-0486    

DOI:10.1002/jrs.1250220303

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe Raman spectra (3200‐10 cm−1) of dichloroacetyl fluoride (CHCL2CFO) of the gas, liquid (with qualitative depolarization ratios) and solid were recorded. The infrared spectra (3200‐30 cm−1) of the gas and solid were also obtained. All of these data indicate atrans/gaucheequilibrium in the gas and liquid whereas only thegaucheconformation remains in the solid. A complete vibrational assignment is proposed for both conformers based on the Raman depolarization data, infrared band contours, group frequencies and normal coordinate calculations. From the studies of the Raman spectra at various temperatures, the enthalpy difference between the stable conformers was determined to be 315 ± 68 cm−1(0.90 ± 0.19 kcal mol−1) (1 kcal = 4.184 kJ) and 180 ± 4 cm−1(0.51 ± 0.01 kcal mol−1) for the gas and liquid, respectively, with thetransconformer being more stable in the gas but thegaucheconformer more stable in the liquid. These experimental results are compared to those obtained fromab initioHartree‐Fock gradient calculations with the RHF/3‐21G* and RHF/6‐31G* basis sets, and to the corresponding quantities obtained f

ISSN:0377-0486    

DOI:10.1002/jrs.1250220304

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe Raman (3500‐20 cm−1) and infrared (3500‐50 cm−1) spectra of gaseous and solid 2‐fluoropropane, (CH3)2CFH, the corresponding trideuterated molecule, (CH3)(CD3)CFH, and heptadeuterated species, (CD3)2CFD, were recorded. Additionally, the Raman spectra of the pure liquids were recorded and qualitative depolarization values were obtained. All 27 of the normal vibrational modes were assigned for all three isotopic species based on infrared band contours, depolarization values, isotopic shifts and group frequencies. The vibrational assignment is supported by anab initiocalculation utilizing the 3‐21G basis set to obtain the force constants and potential energy distribution. Additionally,ab initiocalculations were carried out utilizing the 6‐31G* basis set to obtain structural parameters and barriers to internal rotation. All of these results are compared with the experimentally determined values and with the corresponding results for some rela

ISSN:0377-0486    

DOI:10.1002/jrs.1250220305

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe composition of the dissolution layer of certain divalent metal nitrates crystals such as Mg(NO3)2, Ca(NO3)2, Zn(NO3)2and Cd(NO3)2in their respective undersaturated solutions was studied by Raman microspectrometry using multi‐channel acquisition of data. A preliminary examination of homogeneous saturated and 20% undersaturated solutions of every solute considered confirmed the existence of individual Raman bands which could be assigned to different solvated species, namely free aquated ions, solvent‐separated ion pairs and contact ion pairs. Some spectral differences were noted between the four cations involved. With Ca2+, Zn2+and Cd2+a weak band, assigned to ion aggregates, was also identified. Micro‐Raman spectra of dissolution layers recorded at several steps of the crystal dissolution showed a considerable increase in the proportions of aggregates or contact ion pairs, depending on the type of solute examined. Sharp differences between the dissolution layer composition for Group IA, IIA and IIB metal nitrates were obs

ISSN:0377-0486    

DOI:10.1002/jrs.1250220306

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractL‐Arginine phosphate monohydrate (LAP) is a recently discovered organic non‐linear crystal which has the potential to replace a conventional crystal such as potassium dihydrogen phosphate. The polarized Raman and infrared spectra of a single crystal of LAP have been recorded to determine the symmetries of the molecular vibrations. The lattice lines are fairly strong compared with the others and show pronounced intensity variations with the orientation of the crystal. The high‐frequency lines are assigned to the vibrations of the various molecular groups such as NH3+, NH2+, NH2, CH2, CH, COO−, H2O and H2PO4−present in th

ISSN:0377-0486    

DOI:10.1002/jrs.1250220307

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractRaman studies are reported of conformational change in an alkyl polyoxyethylene non‐ionic surfactant associated with coordination to alkali and alkaline earth metal cations. This surfactant has a simpler mix of conformers (with TTT relatively unimportant) compared with non‐ionic surfactants incorporating an aromatic ring in the hydrophobic head‐group. This relatively simple conformational pattern facilitates the interpretation of the 868 cm−1band assigned to a TGTTḠT (T,trans; G,gauche; Ḡ,gaucheminus) for the OCH2CH2OCH2CH2O polyoxyethylene sequence associated with surfactant‐cation complexes. Counter anions such as halides appeared to have a negligible effect on

ISSN:0377-0486    

DOI:10.1002/jrs.1250220308

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe resonance Raman spectrum of the radical anion of 2,2′‐bipyridine obtained under cation‐free conditions is reported. Decisive evidence for a transoid structure is given. Force constants for the transoid radical anion were deter

ISSN:0377-0486    

DOI:10.1002/jrs.1250220309

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe silver colloid surface‐enhanced Raman scattering (SERS) spectrum of phenylpropanolamine (PPA) and the surface‐enhanced resonance Raman scattering (SERRS) spectrum of the PPA‐ninhydrin reaction product were studied. It was found that the spectral intensity varied with time, and the rate of the variation was related to the PPA concentration. From scanning electron microscopic photographs taken at different times, the SERS intensity appeared to be correlated with the coagulation of silver particles. Temperature was found to be another factor that would change the kinetic rate of the coagulation. Addition of potassium chloride served effectively to activate the surface‐enhanced effect and to reduce the time required to reach maximum intensity. The rate of activation was found to be dependent on the concen

ISSN:0377-0486    

DOI:10.1002/jrs.1250220310

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

ISSN:0377-0486    

DOI:10.1002/jrs.1250220301

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY