INDUCED INFRARED-ABSORPTION OF HD PHYSISORBED ON NACL FILMS - A 2ND ADSORPTION SITE

In addition to our previously reported study of physisorption of hydro gen to Na+ sites on the (100) faces of NaCl crystallites [Dai and Ewin g, J. Chem. Phys. 98,: 5050 (1993)], there is a second site (the Cl- i on) available for adsorption. Here, we report the induced infrared abs orption of HD adsorbed on this second site. The infrared transition of these adsorbed HD molecules is blue shifted by 10 cm(-1) from the abs orption of the first adsorption site molecules. Isotherms of HD on the second site yield an isosteric heat of adsorption of -1.7+/-0.5 kJ/mo l, or approximately half that for the first site.