Low–energy electron–induced oligomerization of condensed carbon Tetrachloride

CHED 1421

Lachelle D. Weeks, lweeks@wellesley.edu, Lin Zhu, lzhu@wellesley.edu, Marina Pellon, mpellon@wellesley.edu, David R. Haines, DHaines@Wellesley.edu, and Christopher R. Arumainayagam, carumain@wellesley.edu. Department of Chemistry, Wellesley College, Wellesley, MA 02481-0223
The low-energy electron-induced chemistry of condensed CCl4 has been investigated using post-irradiation temperature programmed desorption. These experiments were partly motivated by the growing interest in developing facile and economical methods for decomposing CCl4 and other halocarbons which through widespread use in industry have become potent environmental pollutants. The experimental procedure involves low-energy (50 eV) electron irradiation (fluence < 2 x 1016 electrons cm-2) of nanoscale thin films (5 monolayers) of CCl4 grown at 100 K on a Mo(110) single crystal under ultrahigh vacuum (UHV) conditions. Results of post-irradiation temperature programmed desorption experiments were used to identify C2Cl4, C2Cl6, C3Cl6, C4Cl6, and C5Clx as low-energy electron induced reaction products of condensed CCl4. Two longer chain chlorocarbon oligomers with six or more carbons were also detected but not identified. Although low-energy electron-induced oligomerization reactions have been previously reported, the results presented herein represent the first study to specifically identify the products of such reactions, demonstrating the utility of post-irradiation temperature programmed desorption experiments to study the radiation chemistry of condensed matter.