Search for vibrational activation in the chemisorption of methane

Abstract

Direct laser excitation of the excited ν3 and 2ν4 vibrational modes of CH4 has been used to determine whether either state is active for inducing CH4 dissociative chemisorption on the (111) surface of Rh. The upper limit of the efficiency of chemisorption from either of these states was measured to be approximately 5×10−5. This experimental finding suggests that thermally activated dissociation of CH4 on metal surfaces may proceed via hydrogen atom tunneling from higher excited states or via H⋅⋅⋅H vibrational extensions which are greater than those experienced in the excited ν3 or 2ν4 vibrational states.