Y. Susuki, ENERGY-LOSS H-2(+) IONS UNDER GLANCING-ANGLE INCIDENCE ON A SNTE(001)SURFACE( FRAGMENTS ARISING FROM DISSOCIATION OF FAST H), Physical review. A, 56(4), 1997, pp. 2918-2929
Energy losses of H+ fragments repelled parallel and antiparallel to th
e beam direction at dissociation are measured for a glancing-angle inc
idence of 0.15-0.6-MeV/amu H-2(+) ions on a clean (001) surface of SnT
e. The sum of the energy losses of the specularly reflected fragments
is larger than twice that of protons of the same velocity reflected fr
om the surface. For the interpretation of the vicinage effect on the s
topping power of the surface, the energy losses of the pairs of fragme
nts resulting from the dissociation of H-2(+) are calculated at the gl
ancing-angle scattering. The contribution of single-electron excitatio
n to the energy-loss of the pair is calculated with the harmonic-oscil
lator model [J. Basbas and R. H. Ritchie, Phys. Rev. A 25, 1943 (1982)
] and that of collective excitation by the superposition of surface wa
kes of two protons. A dependence of the vicinage effect on the distanc
e from the surface is found from the calculated stopping powers-where
the pronounced effect becomes weak as the distance decreases. The calc
ulated energy losses of the reflected pairs of protons agree fairly wi
th those measured. The agreement of the calculated energy losses with
those measured supports the calculated dependence of the vicinage effe
cts.