Methanol Production from Methane in Lithium-Doped Argon Matrixes by Photoassisted, Dissociative Electron Attachment to N2O

Photolytic generation of methanol from methane in Ar matrices containing Li and N{sub 2}O is proposed to occur via a UV-light-induced electron transfer from Li to N{sub 2}O to form N{sub 2}O{sup -}. A weak ground-state interaction between Li and N{sub 2}O is suggested by the observation of a Li-N{sub 2}O complex which decays rapidly during the initial stages of the reaction. N{sub 2}O{sup -} is believed to decompose spontaneously or, following photo-excitation, to form N{sub 2} and O{sup -}. The O{sup -} thus formed, or O({sup 1}D) produced via photodetachment from O{sup -}, then reacts with methane to form methanol. An electron is believed to be transferred to a nearby Li{sup +} ion in the process, thereby regenerating the initial electron donor and allowing significant amounts of N{sub 2}O to be consumed, despite the limited amount of Li available in the matrix. Formation of the formaldehyde/water complex during the latter stages of the reaction occurs as a result of secondary reactions of methanol with O{sup -} or O({sup 1}D). The wavelength cutoff of 350-400 nm for the process is in reasonable accord with the predicted threshold for formation of a Li{sup +}/N{sub 2}O{sup -} ion pair in an Armore » matrix. The unusual dependence of the rate of methanol production, in irradiation time, with N{sub 2}O concentration in the matrix is interpreted as arising from a reversible, redundant electron transfer from Li to N{sub 2}O. 28 refs., 9 figs.« less