INTERACTION OF TRAPPED METASTABLE EXCITED HE ATOMS WITH SOLID NOBLE-GASES, NE, AR AND KR, INVESTIGATED BY EPR

Local metastable excited states are found in Ne, Ar and Kr cryocrystal s as He gas-discharge products are trapped in the growing cryocrystals . These states are detected by EPR and are interpreted as being local metastable excited np(5)(n + 1)s(3)P(2) atomic-type states in Ne, Ar a nd Kr cryocrystals. Analysis of the results allows the following expla nation of the observed effect to be given. For the Ne cryocrystal the effect is interpreted as a new phenomenon: quasi-resonance transfer of excitation energy from the metastable He 2(3)S(1) atom trapped in a g rowing neon cryocrystal to the exciton energy band of the neon crystal followed by the exciton self-trapping into the 2p(5)3p state and subs equent decay, ending in the 2p(5)3s(3)P(2) state recorded by EPR in ou r experiment. In the case of Ar and Kr cryocrystals the effect is expl ained as being due to an internal ionization of the cryocrystals by th e excitation energy of trapped metastable He atoms, which implies the formation in the cryocrytal of a Rg(+) ion and a free electron in the conduction band, whereupon the fast (of 10(-12) s) self-trapping react ion of a hole follows: Rg(+) + Rg --> Rg(2)(+). Thereafter the dissoci ative recombination reaction Rg(2)(+) + e --> Rg(2)* --> Rg + R g*(P- 3(2)) could take place.