|
|
| Type |
Oral Presentation |
| Area |
Oral Presentation for Young Scholars in Physical Chemistry |
| Room No. |
304호 |
| Time |
THU 09:29-: |
| Code |
PHYS.O-3 |
| Subject |
Adsorption State of Ammonia on a Crystalline Ice Surface |
| Authors |
이두형, 강헌*
서울대학교 화학부, Korea
|
| Abstract |
Researchers have studied the adsorption of ammonia on ice (and water) surfaces for a long time because it has an importance in various parts of nature such as involvement in chemical reactions in atmosphere and space, but many of the details are still in a veil. Hence we investigated the ammonia adsorption state on crystalline ice Ih surfaces.
Ammonia-adsorbed thin crystalline ice films were prepared on Pt(111) single crystal surface in an ultra-high vacuum environment and analyzed with surface-sensitive techniques including temperature-programmed desorption (TPD), Cs+ reactive ion scattering (RIS), low-energy sputtering (LES), and film voltage measurement using a Kelvin workfunction probe.
The ammonia desorption from crystalline ice surfaces was completed before 150 K. Also, protonated products of ammonia were not detected in the LES experiment. In the Kelvin probe measurement, ammonia adsorption changed film voltages of ice films more positive.
From the desorption spectra, penetration and desorption behavior of ammonia were discussed. An analysis of the change in the film voltage showed an anisotropic distribution of ammonia molecules at ice surfaces. This directional adsorption was induced by the stronger hydrogen bonding between a nitrogen atom of ammonia molecules and a dangling hydrogen atom of ice surfaces than the bonding between hydrogen atom of ammonia molecules to a dangling oxygen atom on the ice surfaces. However, the molecules were not strictly perpendicular to the surface, but had a tilted orientation. It is inferred from the saturation of the film voltage change that the surface density of dangling H on crystalline ice surface was one fourth monolayer to the surface ice molecules, which is the same as the ideal model of crystalline ice.
|
| E-mail |
ldhg@snu.ac.kr |
|
119th General Meeting of the KCS