Green emission of mercury sulphide (α-HgS)

Abstract

The green cathodoluminescence of natural and synthetic mercur sulphide (α‐HgS) is investigated. It is interpreted in terms of an edge emission involving a phonon with an energy of ≈ 20 meV. The transitions are of the bound‐to‐bound type at liquid helium, and of the free‐to‐bound type for higher temperatures. The complexity of the emission makes it difficult to interpret it by a clearly‐defined model. Donor states with bound energies of ED ≧ 8 meV and 20 meV < ED < < 30 meV and acceptor states with an energy of ≈ 40 meV are involved in the emission.

Determination of certain trapping parameters in mercury sulphide (α-HgS) by Thermally Stimulated Conductivity

“…Its photoconductivity has enabled some authors [11,12,13] to propose several depths of impurity levels. Presently, this type of measurements is being undertaken at our laboratory in order to relate it with those of cathodoluminescence and photoluminescence which have already allowed us to explain certain level depths [14,15,16]. An article on this subject is to be published in a next future.…”

Colour degradation of artworks: an ab initio approach to X-ray, electronic and optical spectroscopy analyses of vermilion photodarkening

“…Although in principle our G 0 W 0 results do not give access to optical properties (due to the neglect of particlehole excitations), such favorable comparison suggests that excitonic coupling does not lead to a large difference between the electronic and optical gaps, and thus that excitonic effects in this compound are relatively small, conrming previous experimental ndings. 47 However, from the theoretical point of view, identication of a material's colour requires a calculation of its optical absorption spectrum, whose onset is determined by the optical band gap and which is accessible only by going beyond a single (quasi-) particle perturbative approach through solution of the Bethe-Salpeter equation (BSE).…”