Luminescence and formation of alkalihalide ionic excimers in solid Ne and Ar

Spectroscopy in Cryocrystals and Matrices

Анотація

Transitions from ionic states A²⁺X^– of alkalihalides CsF, CsCl and RbF isolated in solid Ne and Ar films recorded under pulsed e-beam excitation are studied. The B(²∑_1/2)-X(²∑_1/2) and C(²П_3/2)-A(²П_3/2) luminescence bands of Cs2+F– (196.5 nm, 227 nm), Cs²⁺Cl^– (220.1 nm, 249.2 nm) and Rb²⁺F^– (136 nm) in Ne, and a weakerB–X emission of Cs²⁺F^– (211.2 nm) in Ar are identified. For CsF the depopulation of the A²⁺X^– state is dominated by the radiative decay. A ratio of the recorded exciplex emission intensities of I(CsF)/I(CsCl)/I(RbF) = 20/5/1 reflects the luminescence efficiency and for RbF and CsCl a competitive emission channel due to predissociation in the A²⁺X^-(B²∑_1/2) state is observed. For these molecules an efficient formation of the state X^*₂ is confirmed through recording the molecular D`(<sup>3</sup>П<sub>2g</sub>)-A`(³П_2u) transition. A strong dependence of the luminescence intensities on the alkalihalide content reveals quenching at concentrations higher than 0.7%.