화학공학소재연구정보센터
Journal of Physical Chemistry A, Vol.107, No.49, 10615-10624, 2003
Sticking of hyperthermal CO to the (0001) face of crystalline ice
We present the results of classical trajectory calculations on the sticking of hyperthermal CO to the basal plane (0001) face of ice I-h, for normal and off-normal incidence at surface temperature (T-s) = 150 K. The sticking probability decreases with the incidence energy (E-i) and with the incidence angle (theta(i)) for theta(i) > 20degrees. At normal incidence, the sticking probability can be fitted to a simple decay function: P-s = 0.9 e(-0.012Ei(kJ/mol)). The energy transfer from the impinging molecule to the surface is found to be efficient and fast: most of Ei is transferred to the surface within 0.5-1.0 ps. For off-normal incidence, the energy transfer becomes less efficient for theta(i) > 20degrees. In the case of backscattering at off-normal incidence, the hotter molecules scatter at larger angles. At high E-i, no surface penetration occurs, but the impinging molecule may damage the surface significantly when it hits the surface in the center of a hexagonal ring. The energy minimization calculations suggest that CO is adsorbed either on top of an OH dangling group, or on top of the center of a water hexagonal ring, interacting mostly with an electron lone-pair oxygen atom in the first monolayer or with a four-coordinated oxygen in the second monolayer. The molecular dynamics calculations predict that the average binding energy of the adsorbed CO is 4.33 kJ/mol, with a maximum value of 10.4 kJ/mol. The results of our calculations are compared with the experimental and the previous theoretical data on the CO-ice and N-2- ice systems.