The 655 articles cited in this review cover developments in the fields of ultraviolet light absorption spectrometry and light absorption spectrometry during the period December 1977 through November 1979, primarily documented in Chemical Abstracts. An extensive section of the review is devoted to the chemical aspects involved in the development of suitable reagents, absorbing systems, and methods for spectrophotometric analysis. Principles associated with the measurement of ultraviolet and visible radiant energy as well as the instrumentation used for these measurements are reviewed in the section entitled, Physics. Spectrophotometric methods for the determination of metals and of certain organic compounds are tabulated with matrix material, method or reagent, and appropriate reference number from the bibliography being specified. (BLM)

Ultraviolet and Light Absorption Spectrometry

Microcomputer assisted, single beam, photoacoustic spectrometer system for the study of solids

The visible and near IR spectrum of the U4+ ion has been studied by several authors, including aqueous solution studies1 and work on UF2,3 4, UC14 4, and U4+ in CaF2. The last experiment resulted in a spectrum which was sharper than that obtained for pure UF4, and the spectra features were assigned according to the prescription of Spedding.6 While good agreement between the calculated and experimental energies was obtained, the matter of U4+ site symmetry in CaF2 has not been resolved. The actual symmetry of U4+ in UF4 is an eight-cordinate, distorted square antiprism with U-F bond distances ranging from 2.249 A to 2.318 A (cf ref. 7, 8). Such low U4+ site symmetry makes a group theoretical analysis of electronic states from the f2 ion of little aid in the assignment of the Russel-Sanders atomic states and their respective J term microstates. This low site symmetry, and the resulting J term splitting, may in part cause the wide peak widths observed in UF4 (and U02).

Photoacoustic and Absorption Spectra of UF4

Recent studies concerning uranium plasma chemistry have confirmed the generally complicated nature of uranium chemistry1. Uranium plasma, generated by either rf-heating or dc arc torch argon heating of uranium hexafluoride, tends to react with its environment to produce among other compounds both fluorides and oxy-fluorides. The products are characterized as amorphous, powdery deposits. While uranyl fluoride can be identified readily by its infra-red absorption band, uranium tetrafluoride is not easily analyzed by any routine, non-destructive technique. Procedures such as Ion Scattering Spectroscopy and Secondary Ion Mass Spectrometry are expensive and time consuming; while, X- ray and electron deffraction can not overcome the amorphous nature of the plasma deposits.

D. R. Anton

Papers

Qualitative analysis by photoacoustic spectroscopy of amorphous uranium tetrafluoride deposits