摘要:

As flame emission and atomic absorption spectrometry become more extensively used in science and industry, the need for improved precision and accuracy becomes apparent. The relative standard deviation of flame emission methods reported in the literature varies from 1 to 5 percent (1). With the present instrumentation, a relative standard deviation of about one percent can be maintained for most elements.

ISSN:0038-7010    

DOI:10.1080/00387016908050005

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

The determination of selenium by atomic fluorescence spectroscopy has been reported recentlyinteraliaby Dagnall, Thompson and West1,2, and by Marshall and West3. These workers obtained detection limits of 0.15 p.p.m. using an instrument with a slit width ofca. 2mm, and 10 p.p.m. using an instrument with a slit width of 0.lmm respectively, using air-propane flames. The apparatus used in this investigation consisted of a Southern Instruments A 1740 grating flame photometer fitted with Hamamatsu U.V. sensitive photomultipliers and a grating blazed at 300 nm. The monochromator provided with this instrument provides facilities for integration and automatic flame background correction, but has a fixed slit width of only 0.lmm. Using this instrument in conjunction with a selenium electrodeless discharge tube source operating at 2450 MHz and an air-acetylene flame, a detection limit of 1 p.p.m. was obtained at 196.lnm for aqueous solution when an integration period of 20 secs. was used. The A 1740 monochromator was then reglaced by an A 1750 nonochromator which has a slit width variable between 0.025 and l.0mm. When a Imn slit was used in conjunction with flame background correction and a 20 sec. integration period, a detection linit of 0.2 p.p.m. was obtained. In this instance, the detection limit woras taken as the concentration for which the signal is twice the standard deviation.

ISSN:0038-7010    

DOI:10.1080/00387016908050006

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

Several publications have dealt with attempts to assign characteristic infrared frequencies to functions containing polyvalent iodine.1-3We wish to report here a study of the infrared and Raman spectra of some substituted phenyliododichlorides leading to the assignment of bands in the range 260-285 cm−1to I-Cl stretching vibrations.

ISSN:0038-7010    

DOI:10.1080/00387016908050007

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

Compounds with the common formula MAF6.6H2O, where M is a bivalent transition metal and A a quadrivalent element, form a large series of fluorocomplexes which so far has undergone little study. Besides MAF6.6H2O, zirconium and hafnium likewise form more complex compounds with the composition1M2AF8.12H2O and Cd2AF8.6H2O, their complex anion structure still being vague.

ISSN:0038-7010    

DOI:10.1080/00387016908050008

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

A number of semi-empirical methods for approximation to full LCAO-SCF calculations have been developed in recent years. Of these, the CNDO method of Pople and coworkers limited to valence-shell electrons is of particular interest since it takes proper account of electronic repulsion and introduces the symplifying ZDO approximation into the Roothaan equations1-6.

ISSN:0038-7010    

DOI:10.1080/00387016908050009

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:10.1080/00387016908050004

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor