Toward an Understanding of the Surface Chemical Properties of Ice: Differences between the Amorphous and Crystalline Surfaces

Abstract

The interactions of several compounds with the surfaces of amorphous and crystalline ice-h2 and ice-d2 in ultrahigh vacuum were studied using temperature-programmed desorption (TPD) and Fourier transform infrared reflection absorption spectroscopy (FTIRAS). The following compounds were studied: acetone, acetonitrile, carbon tetrachloride, chloroform, diethyl ether, 1-hexene, and 2-propanol. Without exception, compounds possessing a functional group capable of accepting a hydrogen bond from the OH group of water show one or more thermal desorption states from amorphous ice that are absent from the crystalline surface. Conversely, for compounds with no such functional group, the desorption spectra from amorphous and crystalline ice are essentially identical. The unique states exhibit kinetic isotope effects for desorption from ice-d2, whereas states that are common to both amorphous and crystalline surfaces exhibit no isotope effect. FTIRAS measurements show that adsorption of good hydrogen bond donors on ...