| Autor: |
Michon MA; Department of Chemistry, Brown University, Providence, 02912, Rhode Island, USA. peter_weber@brown.edu., Chmielniak P; Department of Chemistry, Brown University, Providence, 02912, Rhode Island, USA. peter_weber@brown.edu., Weber PM; Department of Chemistry, Brown University, Providence, 02912, Rhode Island, USA. peter_weber@brown.edu., Rose-Petruck C; Department of Chemistry, Brown University, Providence, 02912, Rhode Island, USA. peter_weber@brown.edu. |
| Abstrakt: |
High-lying electronic states hold the potential for new and unusual photochemical reactions. However, for conventional single-photon excitation in the condensed phase, reaching these states is often not possible because the vacuum-ultraviolet (VUV) light required is competitively absorbed by the surrounding matrix rather than the molecule of interest. Here, this hurdle is overcome by leveraging nonresonant two-photon absorption (2PA) at 265 nm to achieve preferential photolysis of tetrahydrofuran (THF) trapped within a clathrate hydrate network at 77 K. Electron spin resonance (ESR) spectroscopy enables direct observation and identification of otherwise short-lived organic radicals stabilized by the clathrate cages, providing clues into the rapid dynamics that immediately follow photoexcitation. 2PA induces extensive fragmentation of enclathrated THF yielding 1-alkyl, acyl, allyl and methyl radicals-a stark departure from the reactive motifs commonly reported in γ-irradiated hydrates. We speculate on the undetected transient dynamics and explore the potential role of trapped electrons generated from water and THF. This demonstration of nonresonant two-photon chemistry presents an alternative approach to targeted condensed phase photochemistry in the VUV energy range. |
