摘要:

A preatomizing (charring) step is customarily used in flameless atomic absorption spectroscopy. Experiments were carried out to investigate the effect of the charring temperature on the final response and to determine at what temperature significant losses were occurring. Four elements of environmental significance (Pb, Cd, Be, V) were investigated in three matrices obtained from air pollution studies.

ISSN:0038-7010    

DOI:10.1080/00387017408067258

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Harmonic force fields for AlBr3and Al2Br6, are developed. The vibrational assignment for the latter molecule is discussed. Calculated mean amplitudes for both molecules are reported.

ISSN:0038-7010    

DOI:10.1080/00387017408067259

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The wavelength dependence of the optical absorption of solids, liquids and solutions has long been recognised as an indicator of electronic transitions and hence the associated electronic structure of these materials. With solids and highly ordered systems, a useful extension is the study of the absorption at a given wavelength (λ) as a function of the state of polarisation of incident, linearly polarised light. Such ‘dichroism’ data enable one to locate the principal directions of the transition moments in the crystal should a single absorbing chromophore be the sole origin of the effect. This may be done by evaluating the principal components11with i = 11, 2 or 3 of the extinction coefficient tensor which describes the system. For cylindrically symmetric particles,11=22. Dispersion data of dichroism is thus of double value.

ISSN:0038-7010    

DOI:10.1080/00387017408067260

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

In a preliminary report1it was shown that the hydrogen-bond chemical shift, δAB, correlates with the change in enthalpy, δH, in the interaction of chloroform with a series of closely related oxygen and nitrogen bases. In this communication, we report the hydrogen bonding parameters for the interaction in cyclohexane medium between 2,4,6-tri-t-butylphenol and tetrahydrofuran, tetrahydropyran and pyridine, and between 2,6-di-1-adamantyl-4-t-butylphenol and pyridine. There is correlation between the δABand δAEfor the same proton donor (2,4,6-tri-t-butylphenol) and the closely related alicyclic bases, and for the same base (pyridine) and the two closely related sterically hindered phenols. The temperature dependence of the δABin these systems is also reported.

ISSN:0038-7010    

DOI:10.1080/00387017408067261

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

In the course of an investigation into the reactions of ethynyl radicals with alkynes1, monobromoethyne and certain polyalkynes were synthesized and their infra-red spectra were recorded. Although the spectra of certain of the compounds have been well-documented, others are less familiar and, in the case of two dialkynes, no record can be found of their vibrational spectra.

ISSN:0038-7010    

DOI:10.1080/00387017408067262

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Substitution of a carboxyl group onto the 9 position of anthracene, as in 9-methyl anthroate (9-COOMe), results in some significant differences in the spectral properties of the ester relative to those of the anthracene parent molecule. For example, the fluorescence quantum yield (øf) and fluorescence maximum (υmax) of 9-COOMe become quite solvent dependent due to an excited state geometry change in which the excited singlet takes on significant charge transfer character (1,2).

ISSN:0038-7010    

DOI:10.1080/00387017408067263

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The reactions of ethylene induced by irradiation with a relatively low power, continuous CO2laser were studied. Ethylene and ethylene oxygen mixtures were irradiated using a laser beam of power (a) 25 watts and (b) 40 watts. Ethylene irradiated with a 25 watts laser produced propylene as the major product in a slow reaction. An 80:100 ethylene-oxygen mixture with a laser power of 25 watts produced a faster reaction, with acetaldehyde, 1,3-butadiene and benzene as major products. Both ethylene and an 80:20 ethylene:oxygen mixture produced methane propylene and 1,3-butadiene as major products when irradiated with 40 watts of, laser power.

ISSN:0038-7010    

DOI:10.1080/00387017408067264

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Recently, Combs and Holloman have reported anomalous energy minima in approximate SCF calculations on bending modes in several small molecules.1′2The methods employed (CNDO/2 and INDO)3are currently in wide use and it would be helpful to have a clear view of the origin(s) of these anomalies. [As has been demonstrated,2reparameterization to remove these features creates more serious problems than that for which the remedy was derived.] We were particularly concerned as recent studies have shown that INDO wavefunctions, when properly handled, provide a qualitatively correct description of the electronic charge distribution in selected diatomic molecules.4Further, these methods are extensively used for studies of molecular deformations.5

ISSN:0038-7010    

DOI:10.1080/00387017408067265

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Electrogenerated chemiluminescence (ECL) provides an unusually attractive method for producing dimeric luminophors, by comparison to optical pumping of a dye laser, both in terms of dimer/monomer ratio and variety of accessible states. Several dimeric luminophors arising from the homogeneous charge transfer step are discussed, and the customary assignment of full singlet or triplet character to some of the excited moieties is shown to be unwarranted. An error in the literature concerning the kinetics of ECL-dimer formation is pointed out.

ISSN:0038-7010    

DOI:10.1080/00387017408067266

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:0038-7010    

DOI:10.1080/00387017408067257

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor