Optical band gap of the a-mercuric iodide

Abstract

We investigate by photoacoustic spectroscopy the optical band-gap energy of mercuric iodide, a-HgI*, grown by sublimation in a sealed ampoule. Due to its importance as a detector material operating at ambient temperature, the physical properties of a-HgI, have been recently studied. We found, by two different methods, the band-gap energies E,=2.32 and 2.39 eV, respectively. These results are in good agreement with recent measurements based on reflection and absorption spectra.