STRUCTURE SENSITIVITY IN THE SURFACE-CHEMISTRY OF ICE - ACETONE ADSORPTION ON AMORPHOUS AND CRYSTALLINE ICE FILMS

The adsorption of acetone on ice under ultrahigh vacuum has been investigated using temperature-programmed desorption mass spectrometry and single-reflection Fourier transform infrared spectroscopy. Two types of film were investigated: amorphous ice, which has a high density of free surface OH groups, and crystalline ice, on which free OH groups are not spectroscopically detected. On the amorphous film, two states of acetone are observed during temperature-programmed desorption, one derived from acetone which forms a hydrogen bond with the ice surface and a second which is attributed to the desorption of physisorbed acetone. Only the physisorbed state is observed during desorption from a crystalline ice film. This work provides clear and convincing evidence that the surface properties of amorphous ice are different from those of crystalline ice.