摘要:

Despite of its pharmaceutical interest, the vibrational spectrum of caffeine has not yet been described. In this work, the infrared (and in part the Raman) spectra of caffeine and its hydrochloride dihydrate are investigated.

ISSN:0038-7010    

DOI:10.1080/00387018608069240

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Analysis of the N-H1H-NMR chemical shifts of the bis-pro-pionate ions of bilirubin IXα and XIIIα reveals a preference in CDCl3and d6-DMSO for folded conformations in which the propionate groups are intramolecularly H-bonded to the opposing pyrromethenone units.

ISSN:0038-7010    

DOI:10.1080/00387018608069241

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The fluorescence quantum efficiencies of benzoic acid, toluic acid isomers, and anisic acid isomers in 10% glacial acetic acid-chloroform solvent are reported. The values of fluorescence quantum efficiencies of benzoic acid derivatives are compared with the quantum efficiency of the parent molecule (benzoic acid). The molar extinction coefficient of each compound in the above solvent at wavelength of maximum absorbance (εmax) is also measured. Since the molar extinction coefficient and the fluorescence quantum efficiency for a specific excitation wavelength are characteristics of a compound, the product of these constants for each isomer is given to compare the fluorescence of these isomers with each other. This study shows that the fluorescence of all isomers is enhanced compared to the fluorescence of benzoic acid.

ISSN:0038-7010    

DOI:10.1080/00387018608069242

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A new spectrophotometric method was employed for the determination of lead (II) based on the ternary complex formation with 2-(5-Bromo-2-Pyridylazo)-5-diethylaminophenol(5-BrPADAP) and cetyltri-methyl-ammonium bromide (CTAB). At pH 7.00 a violet ternary complex, whose molar absorptivity is 5.1×1041.mole−1cm−1at 575 nm, is formed. Beer's law range (0.5 − 4.9 μg ml−1of lead), the apparent stability constant (log β=9.90) and δG° were evaluated. A large number of ions do not interfer at pH 7.00 because they form complexes with 5-Br-PADAP at higher pH's (< 9.40) or at lower pH's (> 4.86). The method offers the advantages of simplicity and requires no extraction.

ISSN:0038-7010    

DOI:10.1080/00387018608069243

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The dielectric absorption spectrum of zeolite ZSM-5, in the range of frequencies 100 c - 10 Mc, was studied. The influence of the crystallization degree and influence of the Si/Al ratio on the amplitude of the dielectric absorption were analysed. It was observed thatmaxdepends on the Si/Al ratio in an exponential form. An excess of Et.OH in the mixture of crystallization influences favorably the kinetics of the process.

ISSN:0038-7010    

DOI:10.1080/00387018608069244

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The dependence of the surface Si/Al ratio in function of the volume Si/Al ratio was studied, for zeolite of type: A, X, clinoptilolite, mordenite and three samples of ZSM-5. Surface measurements were made by Auger electron spectroscopy (AES), and volume (bulk) measurements by atomic absorption spectrophotometry. It was found that the surface Si/Al ratio is identical with the volume Si/Al ratio. The dependence of the surface Si/Al ratio on the crystallization degree for zeolite ZSM-5 was also studied. We obtained some informations about the kinetics and mechanism of the crystallization process.

ISSN:0038-7010    

DOI:10.1080/00387018608069245

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The Raman Spectra of the thermochromic tetraiodomercurates of Ag(I), Cu(I), Hg(I), Tl(I), Hg(II) and Pb(II) have been obtained below and above the transition temperature. The spectra are interpreted in terms of the known crystal structures. The Hg2HgI4shows an interesting behaviour towards light irradiation which has been interpreted in terms of mixed valence states model.

ISSN:0038-7010    

DOI:10.1080/00387018608069246

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

FTIR photothermal beam deflection (PBD) spectroscopy was used to record PBD spectra of IR-absorbing gases in presence of IR-absorbing and non-absorbing solids. The presence of the solid, IR-absorbing or not, causes asymmetry at the juncture of the IR and probe laser

ISSN:0038-7010    

DOI:10.1080/00387018608069247

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

It is interesting to make a comparison of important intensity parameters, such as the Franck-Condon factors1, against experimental values. This is the scope of this work, where we present a comparison of FC factors with our measurements of relative intensity of the P(15) lines of seven bands (43-0, 43-1, 43-2, 43-9, 43-10, 43-11, 43-18, 43-19 and 43-20) of iodine. As laser induced fluorescence has became an important tool in the study of collision dynamics a contribution to the picture of energy release in relaxation processes of a molecule in a high lying vibrational level is of some benefit.

ISSN:0038-7010    

DOI:10.1080/00387018608069248

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

FTIR photothermal beam deflection spectroscopy (PBDS) was used to record infrared spectra of medium-temperature carbons before and after they had been subjected to treatments with aqueous HNO3or H2O2solution. Changes in the functional groups present on the carbon surfaces can be clearly observed.

ISSN:0038-7010    

DOI:10.1080/00387018608069249

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor