A. Bivas

Two-photon absorption in CuCl

Abstract The two-photon absorption spectrum of CuCl at 4.2°K is studied in the energy range of the excitonic lines. The observed lines are suggested to be due to the creation of excitons in the 1S, 2P and 3P states and also to the simultaneous creation of 2P and 3P excitons and one or more longitudinal optical phonons.

Two-photon absorption in CuBr

Abstract The two-photon absorption constant is measured in the exciton region of CuBr. Three exciton lines are observed and interpreted as due to a 1S longitudinal exciton, a 2P exciton and its LO phonon side band. The spectrum is explained by Mahans two-band model.

Intensity dependence of emission lines in CdS upon excitation intensity (laser) at very low temperature

Abstract The dependence of the emission intensity upon excitation intensity (laser) is reported for free exciton recombination (A 1 ) and for phonon-assisted free exciton recombination (A 1 -LO) in CdS at 4.2°K. For an excitation intensity threshold, A 1 becomes sublinear, A 1 -LO superlinear.

Excitonic absorption and emission of cuprous chloride during excitation by a powerful light source

Abstract The excitonic absorption line of CuCl is shifted towards higher energies when the sample is excited by a powerful light source; on the contrary, the emission line is not shifted. Several explanations of these observations are given.

High concentrations of carriers and excitons in copper halides crystals

Abstract Large concentrations of carriers and excitons are created by laser excitation in copper halides crystals at low temperatures. A drastic change of the absorption spectrum of these samples has been observed: decrease and shift of the excitonic lines.

Luminescence of AgCl excited by u.v. laser light

The spectral distribution and decay of the blue-green luminescence of AgCl has been measured at very low temperatures, using u.v. laser excitation. A structure was observed in the emission band at 77°K. The decay consists of three processes: a) a very fast process which follows the laser pulse (10−8 sec), b) a fast exponential process which is also observed with low intensity u.v. excitation,(τ∼10−4–10−5 sec) and, finally, c) a slow exponential process (τ∼seconds).