The fundamental induced infrared absorption of O-2 physisorbed on anne
aled NaCl films is observed for the first time. Analysis of spectrosco
pic and thermodynamic data is consistent with molecules adsorption on
defect sites and on Na+, Cl-, and the center of lattice square of smoo
th NaCl(100) faces of the film crystallites. Isotherms of O-2 On three
smooth-face surface sites at 58 and 60 K are reported with isosteric
heats of adsorption of -9.0+/-1.0, -7.1+/-1.0, and -7.1+/-1.0 kJ/mol,
respectively. The infrared bands of molecules adsorbed on NaCl films a
re close to the gas phase fundamental vibrational frequency. (C) 1996
American Institute of Physics.