摘要:

We wish to report a new method for following the rates of autoxidation reactions, and the use of the method in a study of the autoxidation of styrene. The method involves monitoring the decrease in the ultraviolet absorption band which results from the interaction of oxygen with most organic solvents. This absorption band was discovered by Evans4in 1953. It rapidly appears when oxygen is bubbled through an organic solvent in a UV cell, and it just as rapidly disappears when the solution is purged with nitrogen. Evans at first4aattributed the band to a contact charge transfer complex5between oxygen and the organic solvent. He later suggested4that this band is due to a singlet-to-triplet absorption by the organic material which is enhanced by the presence of the paramagnetic oxygen molecule. This latter explanation is the one which is most commonly accepted today. 6 Table 1 lists the absorption maxima of the Evans peak for several common organic solvents. The only solvent which we have yet discovered which does not have an Evans peak is CC14.

ISSN:0038-7010    

DOI:10.1080/00387016908050016

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

Thorium may not be determined by direct atomic absorption spectroscopy in flame media with appreciable sensitivity because of inefficient atomisation. Earlier papers from this laboratory have described indirect amplification procedures for similarly difficult elements e.g. niobium1and titanium2by atomic absorption spectroscopy· Madison and Guyon3have developed a solution spectrophotometric procedure for thorium in which the heteropoly acid complex of thorium with phosphomolybdic acid is formed and reduced to the ‘heteropoly blue’. Strict adherence to time of addition of reagents is required in this procedure, and. it is necessary to effect an initial separation of the thorium from most other cations present in the sample.

ISSN:0038-7010    

DOI:10.1080/00387016908050017

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

NMR chemical shifts are known for various nuclei in numerous solid compounds. Especially detailed data were obtained for NMR of19F. The present work cites the measurement results for fluorine NMR chemical shifts in several d10-element fluorides previously not investigated. At the same time, the fluorine chemical shift values in alkali, alkali-earth and some other metal fluorides were measured anew. (This was necessitated by the discrepancies in the shift magnitudes, cited by various authors, as well as by the inaccuracy of the mutual chemical shifts of some standards commonly used.

ISSN:0038-7010    

DOI:10.1080/00387016908050018

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

In a recent paper Margoshes1noted that selection of wavelengths for use in atomic absorption spectroscopy is usually based on published information or direct measurement on a number of lines. Further, reliance on the former may not result in the selection of the best wavelength for the experimental and instrumental conditions, and the latter can be very time consuming.

ISSN:0038-7010    

DOI:10.1080/00387016908050019

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

ISSN:0038-7010    

DOI:10.1080/00387016908050020

出版商:Taylor & Francis Group    

年代:1969

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:10.1080/00387016908050015

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor