Morphology, intermixing, and glass transition of amorphous acetic-acid films studied by temperature-programmed TOF-SIMS and TPD

The CH3COOH film deposited at 15 K has microporous structure as evidenced by that the physisorbed Xe atoms are trapped in the bulk. The film dewets abruptly at 150 K where the trapped Xe atoms desorb concomitantly. The self-diffusion of the acetic-acid molecules commences well below the dewetting temperature, and the binary films of the CH3COOH and D2O molecules are intermixed at 130-140 K. It is concluded that the structural relaxation of the CH3COOH film (150 K) is delayed relative to the onset of the translational molecular diffusion due to slow evolution of the fluidity in the supercooled liquid phase.