FTIR Analysis of Dimethyl Ether Decomposition Products Following Charge Transfer Ionization with Ar+ under Matrix Isolation Conditions

Fourier transform infrared spectroscopic analysis has been performed on argon matrices formed following electron bombardment of argon/dimethyl ether mixtures. Products consistent with the ionization and subsequent fragmentation of dimethyl ether cation have been observed. Following ionization of dimethyl ether, fragmentation occurs that is consistent with ionization energy greater than 15 eV due to efficient charge transfer from dimethyl ether to Ar+ as the major ionization process. Major products observed in the infrared spectra are methane, formaldehyde, HCO•, CO, and Ar2H+. These products are consistent with the known fragmentation of photoionized dimethyl ether in a 15−16 eV ionization energy range. However, the observation of dehydrogenated products is consistent with additional abstraction of hydrogen from proximally located species isolated within the matrix. Analogous experiments employing CD3OCH3 give similar results, and the observed isotopically substituted products are consistent with the proposed fragmentation pathways.