Wetting-related adsorption transitions in liquid Ga-Tl alloys

Adsorption of Tl has been measured by Auger electron spectroscopy as a function of temperature at the surface of three liquid Ga-Tl alloys of compositions: 2 x 10(2). 2 x 10(-3), and 5 x 10(4) at.% Tl. The temperature of the prewetting critical point is estimated to be 200 +/- 10 K, whereas the wetting temperature is estimated to lie below 145 K. Thus. it appears that the wetting transition in this system is first order rather than critical. This result is in contrast to previous measurements on the Ga-Pb system, where it was not possible to ascertain the nature of the wetting transition. Taken together, these results indicate that wetting transitions in binary metallic systems with short-range interactions occur at temperatures that are significantly lower in relation to the critical temperatures than is the case in organic liquid systems with long-range interactions. (C) 2001 Elsevier Science B.V. AIR rights reserved.