I1 has teen shown that insulating LiH and LiD transform gradually to a semiconducting state at about 30 GPa and room temperature. It was +so found that these compounds undergo a semiconductoi-to-semmeral transition at about 43 GPa The akserved phenomena can probably @explained by a first-order phase B1-to-B2 structure transition.

An experimental study is made of resonant secondary emission, reflection, and excitation spectra which indicate the existence of bound excitons in LiH-Mg crystals. The spectroscopic properties of the bound exciton are studied by selectively excited luminescence and resonant Raman scattering. The resonance energy of the bound exciton is estimated to be 4.842 eV. For the first time, the transformation of resonant Raman scattering into luminescence is found when the incident photon energy is above the resonance. pacceman B nmM&iHecueHuEIm, KorAa 3~e p r m nanaiouero @oToHa npeBbImaeT 3~e p r~m p e 3 0~a~c~o r o nepexona.

No abstract

The formation of two independent paramagnetic centres Ru(JT) and Ru(A) was detected by the EPR method LiH and LiD single crystals doped with ruthenium, after illumination with visible light at T=77 K. Both centres were assigned to Ru+ with low-spin 4d7 configuration. Ru(JT) centres exhibit a quasidynamical Jahn-Teller effect. The values of tunnelling splitting 3 Gamma and random-strain splitting delta were estimated to be 24 cm-1 and 6.0 cm-1, respectively. The Ru(A) centre was found to have tetragonal symmetry with the unpaired electron in a 4d(3z2-r2) orbital.

The optical absorption, luminescence and EPR methods have been used to study LiH(D) single crystals doped with Ru2+. The formation of new absorption bands and EPR signal was observed after the illumination of crystals with light at T=77 K. The possible model of photostimulated processes in LiH(D):Ru crystals is presented.