Mode-dependent coupling between vibration and translation of product CO2 in CO oxidation on Pd(111)

Abstract

The vibrational temperatures of product C O2 were measured in CO oxidation on Pd(111) as a function of the desorption angle by means of infrared chemiluminescence. The antisymmetric vibration temperature was separately determined from the other vibrational modes from the normalized chemiluminescence intensity. The product C O2 desorption is sharply collimated along the surface normal. The antisymmetric vibrational temperature increased from 1300 to 1600 K as the desorption angle increased from 0° to 30°, whereas the averaged vibrational temperature over bending and symmetric modes decreased from 2450 to 1530 K. From these angle dependences, an energy partitioning model in repulsive desorption is proposed. © 2008 American Institute of Physics.