Photodissociation of adsorbed Mo(CO)6 induced by direct photoexcitation and hot electron attachment. I. Surface chemistry

The adsorption and photodissociation of Mo(CO)6 on potassium‐free and potassium‐preadsorbed Cu(111) and Si(111)7×7 have been studied under ultrahigh vacuum conditions using vibrational spectroscopy and mass spectrometry. It has been observed that Mo(CO)6 adsorbs molecularly on potassium‐free Cu(111) and Si(111)7×7 at 85 K and, upon heating, desorbs at 200 K. In the case of Cu(111), heating also leads to thermal dissociation of a fraction of Mo(CO)6 at ∼150 K. The dissociation channel competes favorably with the molecular desorption channel at low Mo(CO)6 exposures. On potassium‐preadsorbed Cu(111) and Si(111)7×7 at 85 K, Mo(CO)6 adsorbs in part molecularly and in part dissociatively. The extent of dissociation depends on the K coverage; a high K coverage results in large degree of dissociation. The thermal desorption temperature for the molecularly adsorbed Mo(CO)6 increases to 210 K on the potassium‐preadsorbed surfaces. Adsorbed Mo(CO)6 molecules photodissociate nonthermally into CO and carbonyl fragmen...