Na{sup -} photolysis in THF: Charge transfer to solvent studied from the donors perspective in <10 fs detail
- Institute of Chemistry and the Farkas Center for Light Induced Processes, Hebrew University, Jerusalem 91904 (Israel)
Two and three pulse photolysis experiments on terahydrofuran (THF) solutions of Na{sup -}, utilizing hyperspectral probing, are described. The objective is to probe the extent and duration of energetic correlations between the primary charge transfer to solvent (CTTS) fragments which are an e{sup -} and Na{sup 0}. The latter is characterized by an intense visible absorption spectrum with fine structure reflecting the atom's immediate solvent environment. Pump-probe experiments with {approx}6 fs pulses show that for the majority of irradiated ions, the electron ejection and production of unperturbed Na{sup 0} is effectively over in {approx}15 fs, with no precursors. Three pulse experiments further demonstrate this to be true for nearly all ions irradiated at 3 eV. Thus, the 400 nm data provide a detailed spectral record of the formation and subsequent solvation and polarization of neutral sodium bubbles in THF. Measures are presented for parametrizing the ensuing spectral evolution. In contrast, exciting at 1.5 eV, the red edge of the CTTS band leads to charge transfer with less than unity quantum efficiency. The complementary fraction of absorbing ions is photostable at 800 nm, presumably due to preferential solvent stabilization. Prompt secondary irradiation at 2 {mu}m can complete ionization of that population leading to additional generation of Na{sup 0} but exhibiting much more pronounced spectral structure. Thus, at low photon energies, a short lived correlated and bound electronic excited state is produced with significant yield. These results are discussed in terms of classical models for CTTS spectra, as well as more recent simulations and experiments concerning CTTS in this and other related systems.
- OSTI ID:
- 21106210
- Journal Information:
- Journal of Chemical Physics, Vol. 129, Issue 4; Other Information: DOI: 10.1063/1.2946701; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
Similar Records
Photoexcitation of Yb-doped aluminosilicate fibers at 250 nm: evidence for excitation transfer from oxygen deficiency centers to Yb{sup 3+}
Photodissociation dynamics of IBr{sup -}(CO{sub 2}){sub n}, n<15