VALENCE FLUCTUATION STATE OF A METASTABLE HE ATOM BEAM ON A METAL-SURFACE, AND SINGLET-TRIPLET CONVERSION

The time-dependent expectation value of the triplet metastable He atom is obtained by starting from the singlet state and solving the time-d ependent Schrodinger equation directly, to the eighth-order of V, wher e V is the transfer integral between the conduction electron state and the 2s state of the He atom. The results show that rapid singlet-trip let conversion on the low work-function metal surface occurs through t he valence fluctuation state. The quasi-static approximation is demons trated to be valid to the eighth-order of V. The previously conjecture d closed form of the transition rate for the conversion is confirmed.