Photochemical and photophysical processes in condensed phases attract interest because information from these experiments yields detailed knowledge about chemical transformations in extraterrestrial invironments, insight into internal energy transfer and molecular dynamics, and new spectral data for transient species. To study the photochemistry of solid interstellar molecules, we have constructed a 3 K cryostat/FTIR end station coupled to a beam line of a synchrotron at National Synchrotron Radiation Research Center (NSRRC) in Taiwan. Upon excitation in situ of solid samples with light of tunable wave length generated with an electron synchrotron in the vacuum-ultraviolet (VUV) spectral region, the photochemical products were deduced from their absorption spectra in the mid infrared region, recorded, at each stage of an experiment, with an interferometric spectrometer. Taking the advantage of the unique property of synchrotron, we explore the spectroscopy of transient species and photochemistry of solid interstellar molecules with exciting prospects. In this work, infrared and ultraviolet spectra of solid interstellar molecules (e.g. N2, CH4, C2H2, and C2H4) and their photolysis products including the transient species will be presented, with a suggested mechanism of the photochemical and photophysical processes involving atomic and molecular free radicals. Our results contribute important data to improve our understanding of photochemical synthesis of prebiotic molecules via abiotic compounds in the interstellar medium and on icy surfaces of planets and satellites in the solar system.

Investigation of photochemistry of interstellar molecules using synchrotron VUV

246th National Meeting (2013)

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