Low-Energy Electron-Induced Oligomerization of Condensed Carbon Tetrachloride

Abstract

The low-energy electron-induced chemistry of condensed CCl 4 has been investigated with use of post-irradiation temperature-programmed desorption. These experiments were partly motivated by the growing interest in developing facile and economical methods for decomposing CCl 4 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 e2 × 10 16 electrons cm -2 ) of nanoscale thin films (5 monolayers) of CCl 4 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 C 2 Cl 4 , C 2 Cl 6 , C 3 Cl 6 , C 4 Cl 6 , and C 5 Cl x as low-energy electron-induced reaction products of condensed CCl 4 . 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 for molecules such as thiophene and cyclopropane, 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.

Growth and Microstructure of Nanoscale Amorphous Carbon Nitride Films Deposited by Electron Beam Irradiation of 1,2-Diaminopropane

“…To provide complementary information on electron stimulated reaction mechanisms, growth processes, and the influence of irradiation time on the film’s structure, separate experiments were performed under ultrahigh vacuum (UHV) on nanometer scale thick 1,2-DAP films. The value of this UHV experimental approach to probe electron-mediated processes has been demonstrated in recent studies relevant to atmospheric chemistry, − astrochemistry, , astrobiology, thin film modification, − and radiation damage to biologically relevant molecules. ,, …”

Electron Induced Surface Reactions of the Organometallic Precursor Trimethyl(methylcyclopentadienyl)platinum(IV)

“…Under these conditions, the effects of electrons on the adsorbed molecules can be monitored in situ using surface analytical techniques. Indeed, this experimental approach has been successfully employed in a number of recent studies designed to examine electron mediated processes relevant to atmospheric chemistry, − astrobiology, the modification of organic films − including self-assembled monolayers, − and radiation damage to biologically relevant molecules. ,, In regard to electron stimulated reactions of organometallic precursors, Yates et al have studied the effect of low-energy (2−27 eV) electrons on the decomposition of hexafluoracetylacetonate Cu(I) vinyltrimethylsilane, a metal−organic chemical vapor deposition (MOCVD) precursor used for the deposition of copper, on the Si(7 × 7) surface at room temperature . X-ray photoelectron spectroscopy (XPS) results showed that electron stimulated reactions led to the formation of Cu(0) while the threshold for decomposition was ≈4 eV, consistent with a dissociative electron attachment mechanism.…”

Low-Energy Electron-Induced Decomposition and Reactions of Adsorbed Tetrakis(trifluorophosphine)platinum [Pt(PF3)4]

“…Comparable studies have been performed on the electron-induced surface reactions of several EBID precursors such as hexafluoracetylacetonate copper(I) vinyltrimethylsilane, metal carbonyls, − and more recently Au III (acac)Me 2 and MeCpPtMe 3 . UHV surface science studies have also proved effective in studying other electron-mediated processes, including chemical and physical transformations initiated in organic thin films. − …”