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

Abstract

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(²П₃/₂)-A(²П₃/₂) 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`(³П₂g)-A`(³П₂u) transition. A strong dependence of the luminescence intensities on the alkalihalide content reveals quenching at concentrations higher than 0.7%.