| 1. |
- Boyle, Mark, et al.
(författare)
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Two colour pump-probe study and internal energy dependence of Rydberg state excitation
- 2004
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Ingår i: Physical Review A. - 1050-2947. ; 70
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Tidskriftsartikel (refereegranskat)abstract
- Excitation of Rydberg states in isolated C60 is studied by time-resolved photoelectron spectroscopy in a femtosecond two-color pump-probe experiment. The relaxation time for electron-electron interaction is determined to be approximately 100 fs with the t1g(LUMO + 1) orbital being considered to define the doorway state in a nonadiabatic multielectron excitation process. The internal energy stored in vibrational modes of the C60 at 770 K is found to support the excitation process very efficiently while in "cold" C60 (80 K), no significant Rydberg population is detected.
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| 2. |
- Hedén, Martin, 1976, et al.
(författare)
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Determination of the triplet state lifetime of vibrationally excited C-60
- 2003
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 118:16, s. 7161-7164
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Tidskriftsartikel (refereegranskat)abstract
- The lifetime of the ground triplet state of vibrationally excited C-60 has been determined in a two-color pump-probe experiment. An intense pump pulse (337 nm, 4 ns) was used to excite the neutral molecules. The triplet state was probed via single photon ionization with a weak probe pulse (193 nm). The lifetime was found to be on the order of 1 mus. This is rather low to explain recent delayed ionization results but higher than expected from an extrapolation of earlier measurements at lower temperatures. (C) 2003 American Institute of Physics.
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| 3. |
- Mehlig, Kirsten, 1964, et al.
(författare)
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Energy distributions in multiple photon absorption experiments
- 2004
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 120, s. 4281-4288
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Tidskriftsartikel (refereegranskat)abstract
- Photofragmentation experiments on molecules and clusters often involve multiple photon absorption. The distributions of the absorbed number of photons are frequently approximated by Poisson distributions. For realistic laser beam profiles, this approximation fails seriously due to the spatial variation of the mean number of absorbed photons across the laser beam. We calculate the distribution of absorbed energy for various laser and molecular-beam parameters. For a Gaussian laser beam, the spatially averaged distributions have a power-law behavior for low energy with a cutoff at an energy which is proportional to fluence. The power varies between –1 for an almost parallel laser beam and –5/2 for a divergent beam (on the scale of the molecular beam). We show that the experimental abundance spectra of fullerenes and small carbon clusters can be used to reconstruct the distribution of internal energy in the excited C60 molecule prior to fragmentation and find good agreement with the calculated curves
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