The
Rochow process is the most common technology used to prepare
organosilicon compounds on an industrial scale, and yet the mechanism
is still not well understood. It involves the reaction of methyl chloride
(CH3Cl) with silicon, catalyzed by copper. To understand
the elementary steps of the reaction involved, we studied the molecular
adsorption of CH3Cl/Cu(410) at 100 K and its complete desorption
at higher temperatures, 100 K < T
D <
200 K. Temperature-programmed desorption (TPD) spectra show two CH3Cl desorption peaks. We attribute the low temperature TPD
peak (T
D ≈ 120 K) to CH3Cl desorbing from both step-edges and terraces and the high temperature
TPD peak (T
D ≈ 160 K) to CH3Cl desorbing from the step-edges. Infrared reflection–absorption
spectra (IRAS) indicate that at low CH3Cl coverage (Θ
= 0.06 ML), CH3Cl adsorbs with its molecular axis (Cl–C
bond) aligned either parallel or perpendicular to [001]. At high CH3Cl coverage (Θ ≥ 0.09 ML), CH3Cl adsorbs
with its molecular axis aligned perpendicular to [001].