Low-Energy (\u3c 20 eV) and High-Energy (1000 eV) Electron-Induced Methanol Radiolysis of Astrochemical Interest

We report the first infrared study of the low-energy (\u3c 20 eV) electron-induced reactions of condensed methanol. Our goal is to simulate processes which occur when highenergy cosmic rays interact with interstellar and cometary ices, where methanol, a precursor of several prebiotic species, is relatively abundant. The interactions of high-energy radiation, such as cosmic rays (Emax ~1020 eV), with matter produce large numbers of low-energy secondary electrons, which are known to initiate radiolysis reactions in the condensed phase. Using temperature programmed desorption (TPD) and infrared reflection absorption spectroscopy (IRAS), we have investigated low-energy (5–20 eV) and high-energy (~1000 eV) electron-induced reactions in condensed methanol (CH3OH). IRAS has the benefit that it does not require thermal processing prior to product detection. Using IRAS, we have found evidence for the formation of ethylene glycol (HOCH2CH2OH), formaldehyde (CH2O), dimethyl ether (CH3OCH3), methane (CH4), carbon dioxide (CO2), carbon monoxide (CO), and the hydroxyl methyl radical (•CH2OH) upon both low-energy and high-energy electron irradiation of condensed methanol at ~85 K. Additionally, TPD results, presented herein, are similar for methanol films irradiated with both 1000 eV and 20 eV electrons. These IRAS and TPD findings are qualitatively consistent with the hypothesis that high-energy condensed phase radiolysis is mediated by low-energy electron-induced reactions. Moreover, methoxymethanol (CH3OCH2OH) could serve as a tracer molecule for electron-induced reactions in the interstellar medium. The results of experiments such as ours may provide a fundamental understanding of how complex organic molecules (COM) are synthesized in cosmic ices

Pharmacometabolomics of Response to Sertraline and to Placebo in Major Depressive Disorder - Possible Role for Methoxyindole Pathway

10.1371/journal.pone.0068283PLoS ONE87-POLN

Methanol Radiolysis of Astrochemical Interest

Using infrared reflection absorption spectroscopy (IRAS), we have investigated low-energy (5-20 eV) electron-induced reactions in condensed methanol (CH3OH) under ultrahigh vacuum conditions ( 4 × 10−10 torr). In contrast to temperature programmed desorption (TPD), a post-irradiation technique we have used previously to study methanol radiolysis, IRAS does not require thermal processing prior to product detection. Our goal is to simulate processes which occur when high-energy cosmic rays interact with interstellar and cometary ices, where methanol, a precursor of several prebiotic species, is relatively abundant. The interactions of high-energy radiation, such as cosmic rays (Emax 1020 eV), with matter produces large numbers of low-energy (\u3c 15 eV) secondary electrons, which are thought to initiate radiolysis reactions in the condensed phase. Using IRAS we have found compelling evidence for the formation of ethylene glycol (HOCH2CH2OH), formaldehyde (CH2O), dimethyl ether (CH3OCH3), methane (CH4), carbon dioxide (CO2), carbon monoxide (CO), and the hydroxyl methyl radical (•CH2OH) upon low-energy electron irradiation of condensed methanol at 85 K. We have also identified the same nascent radiolysis products following high-energy ( 900 eV) electron irradiation of condensed methanol, a finding which is consistent with the hypothesis that high-energy condensed phase radiolysis is mediated by low-energy electron-induced reactions. The observed formation of radiolysis products at electron energies below 10 eV demonstrates that electron impact ionization cannot be the sole reaction mechanism. The results of experiments such as ours may provide a fundamental understanding of how complex molecules are synthesized in the interstellar medium and comets