LOSS OF MATERIAL FROM GA-IN LIQUID SURFACE DURING BOMBARDMENT BY HYPERTHERMAL TA, PT AND AU ATOMS

We have investigated the loss of incident atoms and of substrate atoms from the surface of the liquid Ga-In eutectic alloy during bombardmen t of the surface with hyperthermal Ta, Pt and Au atoms. Hyperthermal a toms were produced by sputtering solid metallic targets positioned dir ectly above the liquid Ga-In surface. By analyzing material deposited on graphite collector surfaces which surrounded the liquid alloy durin g bombardment, angular distributions were determined for atoms leaving the liquid surface as a result of the bombardment. For all three spec ies of incident atoms, we detected Ga and In as well as the primary sp uttered species on the collectors. The angular distributions for the p rimary sputtered species were strongly peaked in a near-normal directi on consistent with direct reflection from the liquid surface. In all c ases, we observed angular distributions for the Ga which included a br oad peak, centered near the surface normal, although not at the same a ngle as the maximum for the incident species. Such a broad distributio n is consistent with secondary sputtering of the liquid surface by the incoming atoms. The distribution of indium atoms is also suggestive o f sputtering. However, we observed significant asymmetry in the In dis tributions which may be correlated with the angular distributions for the incident species. Our results support previous data indicating tha t surface sputtering (or re-sputtering) and direct reflection of prima ry sputtered atoms are significant mechanisms for the loss of material from surfaces during hyperthermal processes such as sputter depositio n.