PRELIMINARY REPORT ON THE THERMODYNAMIC PROPERTIES OF SELECTED LIGHT-ELEMENT AND SOME RELATED COMPOUNDS.

Abstract

Thermodynamic and related properties of substances important in current high-temperature research and development activities are being investigated. This report describes in detail a variety of recent NBS experimental results and their interpretation. The vibrational spectra of different isotopic varieties of MgF2, MgCl2, CaF2, SrF2, and BaF2 molecules trapped in solid rare-gas matrices were determined and analyzed; this technique particularly defines the bending vibrations, heretofore unreliable but a major factor in the thermodynamic properties of such gases. Preliminary microwave studies of the CsOH molecule indicate it to be linear and with highly anharmonic bending vibrations; these pioneering results important implications for the spectroscopically little investigated hydroxides of all the elements of Groups 1, 2, and 3. Further infrared studies of the borohydrides of aluminum and beryllium show, between the solid and gaseous forms of the beryllium compound, a great difference which is tentatively interpreted. Spectroscopic time histories of aluminum wires exploding in vacuum and controlled atmospheres of nitrogen and oxygen were obtained. Several literature reviews with critical data analysis are included. The present status of the heats of formation of CF4 and selected fluorides of nitrogen, carbon, chlorine, and oxygen is described, with a report of recent NBS flame calorimetry on OF2.

Supplement to Rept. no. NBS-9028 dated 1 Jan 66, AD-485 872L.