Electron transmission through layers of H2O and Xe in the ultrahigh vacuum photoreduction of CH3Cl on Ni(111)

Abstract

The photoreduction of CH₃Cl was used to detect the transmission of electrons through layers of H₂O and Xe on Ni(111) under ultrahigh vacuum (UHV) conditions. At a laser wavelength of 248 nm with H₂O spacers, the electron intensity exhibited a nearly exponential decay to zero signal with the 1/e point at about 2 monolayers. At 193 nm with H₂O spacers, the signal decayed with the 1/e point at about 4 monolayers to a constant value due to the direct photofragmentation of the CH₃ Cl possible at this wavelength. At 248 nm with Xe spacers, the signal decayed by a factor of 4 in the first 2 monolayers, after which the signal was nearly constant and nonzero for at least 64 monolayers, indicating a long electron mean free path. CH₃Br is shown to behave similarly with H₂ O spacers at 248 nm.