Estimates of the heats of adsorption for Pt and Pd monolayers on Ta(110)

The heats of adsorption for Pt and Pd atoms on a Ta(110) surface were estimated using a procedure suggested by Oelhafen. We were able to relate the heats of adsorption for Pt and Pd on Ta(110) to the Ta 4f, Pt 4f, or Pd 4p core-level shifts and to changes in the center of gravity of Ta, Pt, or Pd valence-band states. We estimate that the heat of adsorption is -0.7±{}0.2 eV/atom for Pt on Ta(110) and -0.4±{}0.2 eV/atom for Pd on Ta(110). This work suggests that rough estimates of the thermodynamic parameters for a variety of transition-metal overlayers can be obtained using photoemission.