Thermal accommodation coefficients by high speed vibration of solid samples: VI. O 2 and N 2 on As(111) and Sb(111) single crystal surfaces

Abstract

Translational γ t and rotational γ r energy accommodation coefficients are measured using a high speed vibrational method described earlier. For N 2 on cleaved As(111) single crystal surfaces γ t = 0.34 ± 0.03, γ r = 0.03 ± 0.03; on cleaved Sb(111) single crystal surfaces γ t = 0.49 ± 0.02, γ r = 0.06 ± 0.04. For O 2 on As(111) γ t = 0.39 ± 0.02, γ r = 0.02 ± 0.02; on Sb(111) γ t = 0.56 ± 0.05, γ r = 0.07 ± 0.06. (Uncertainties are statistical estimates of precision. In addition, it is possible that the results are systematically low by up to 10%.) Comparison with N 2 and O 2 accommodation coefficients measured by the same method on other metal substrates suggests that the antimony surface is covered by chemisorbed oxygen but that the arsenic surface is somewhat cleaner. The results are consistent with oxidation of these semimetals occurring by way of physisorbed gas precursor states.