https://doi.org/10.1140/epjd/e2005-00281-7
Excitation dynamics of Rydberg states in C60
1
Max-Born-Institut, Max-Born Str. 2a, 12489 Berlin,
Germany
2
Dept. of Physics, Göteborg University, 41296 Göteborg, Sweden
3
Free University of Berlin, Department of Physics,
Arnimallee 14, 14195 Berlin, Germany
Corresponding author: a cps@mbi-berlin.de
Received:
23
March
2005
Revised:
29
July
2005
Published online:
25
October
2005
The electron and nuclear dynamics of C60 fullerenes
irradiated with femtosecond laser pulses are investigated with
photoelectron and photoion spectroscopy. The focus of this work is
the detailed exploration of the population mechanism of Rydberg
levels within the excitation process of neutral C60. The effect
of excitation wavelength, intensity, chirp, and polarization on the
kinetic energy distribution of photoelectrons in single-pulse
experiments gives first insight into the underlying processes. In
combination with time-resolved two-color pump-probe spectroscopy
depending on either pump, or probe pulse intensity, a more complete
picture of the interaction can be drawn. The results point towards a
very interesting but nevertheless complex behavior including four
steps: (i) non-adiabatic multielectron excitation of the HOMO
(hu) LUMO+1 (
) transition; (ii)
thermalization within the hot electron cloud on a time scale below
100 fs, followed by a coupling of energy to vibrational modes of
the molecule via doorway state(s); (iii) population of
electronically excited Rydberg states by multiphoton absorption, and
(iv) single photon ionization from the excited Rydberg states. This
excitation process results in a characteristic sequence of
photoelectron lines in the photoemission spectra. The comparison of
the experimental results with recent theoretical work gives
convincing evidence that non-adiabatic multielectron dynamics (NMED)
plays a key role for the understanding of the response of C60
to short-pulse laser radiation.
PACS: 36.40.-c – Atomic and molecular clusters / 33.60.-q – Photoelectron spectra / 33.80.Rv – Multiphoton ionization and excitation to highly excited states (e.g., Rydberg states) / 61.48.+c – Fullerenes and fullerene-related materials
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2005