Spectroscopy and Photochemistry of Ketene Adsorbed to Sodium Chloride

Article abstract of DOI:10.1021/j100160a048

Infrared and ultraviolet absorption spectroscopies are used to investigate the photochemistry of ketene (CH2CO) adsorbed to a film of NaCl crystallites.The vibrational spectrum of adsobed ketene resembles that of condensed and matrix-isolated samples: transition frequencies and intensities are only slightly modified.The electronic spectrum, however, shows significant shifts and enhancements due to adsorption.Following 185-nm excitation, adsorbed ketene dissociates with near unit efficiency.Secondary reaction of methylene radicals (CH2) is complete, producing ethylene (C2H4) and carbon monoxide (CO). For 254-nm excitation the quantum yield of dissociation is <10^-2, significantly lower than in the gas.Quenching mechanisms are discussed in light of the known dynamical properties of ketene molecules and NaCl crystals.