The adsorption of elemental mercury vapor on a thin (several hundred angstroms) gold film produces resistance changes in the film. An instrument for the detection of mercury based on this phenomenon is simple and rapid and requires no chemical separations other than passage of the vapor sample through a few standard dry filters. The instrument is portable, and the technique is directly applicable to environmental problems and geochemical prospecting. The limit of detection of the prototype instrument is 0.05 nanogram of mercury.
Infrared and Raman studies have been made on the librational and internal modes of solid CO2 in the pressure range of 6 to 120 kbar at ambient temperature. The Fermi resonance has been analyzed in detail. Both of the stretching modes stiffen with pressure while the bending mode softens with pressure. The magnitude of the Fermi interaction parameter W decreases somewhat with pressure. A simple model using gas phase anharmonic constants predicts much of the observed behavior.
Elastic and piezoelectric constants of CuCl, CuBr, and CuI have been measured. The elastic constants of zinc-blende-structure materials when plotted on a reduced scale indicate a striking instability as the Phillips critical ionicity (0. 785) is approached. CuCl is the most piezoelectric of these materials with a piezoelectric constant e14=0.41 C/m2 at 80°K.
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