CHARGE AND SPIN DYNAMICS OF EXCITED HE ATOM BEAM ON METAL-SURFACES

Analysis is made on the transition rate of conversion from the singlet to the triplet of the excited (1s)(2s) states of a He atom on metal surfaces using an asymptotic expansion under the condition that the affinity level of the singlet is very near to the Fermi level of the metal. Under the same condition, also analyzed is the transition rate from the singlet excited state to the ground state through the negatively charged excited (1s)(2s)2 state of the He atom. Simple forms for the transition rates are proposed and discussed, the recent experimental finding being referred to on the negatively charged excited (1s)(2s)2 state.