Momentum-map-imaging photoelectron spectroscopy of fullerenes with femtosecond laser pulses

• Published in: Physical review. A, Atomic, molecular, and optical physics Vol. 81; no. 2
• Main Authors: Kjellberg, M., Johansson, O., Jonsson, F., Bulgakov, A. V., Bordas, C., Campbell, E. E. B., Hansen, K.
• Format: Journal Article
• Language: English
• Published: United States 01-02-2010
• Subjects: Atom and Molecular Physics and Optics; Atom- och molekylfysik och optik; ATOMIC AND MOLECULAR PHYSICS; BOSONS; CARBON; COMPARATIVE EVALUATIONS; electron spectra; ELECTRON SPECTROMETERS; ELECTRON SPECTROSCOPY; ELECTRONS; ELEMENTARY PARTICLES; ELEMENTS; ENERGY RANGE; ENERGY SPECTRA; EV RANGE; EVALUATION; femtosecond laser pulses; FERMIONS; FULLERENES; IONIZATION; Ionization of fullerenes; LASERS; LEPTONS; MASSLESS PARTICLES; MEASURING INSTRUMENTS; Medicin och hälsovetenskap; NONMETALS; PHOTOELECTRON SPECTROSCOPY; PHOTOIONIZATION; PHOTONS; PULSES; SPECTRA; SPECTROMETERS; SPECTROSCOPY; TIME-OF-FLIGHT METHOD
• ISSN: 1050-2947; 1094-1622
• DOI: 10.1103/PhysRevA.81.023202

Photoelectron spectra of C{sub 60} and C{sub 70}, ionized with ultrashort laser pulses, are measured with a momentum-map-imaging electron spectrometer. Above the photon energy, 1.6 eV, the spectra are essentially structureless and well described by Boltzmann distributions, with temperatures on the order of 10{sup 4} K. This result is similar to previous results for C{sub 60} using a time-of-flight electron spectrometer, which are confirmed in this study. Comparisons of electron energy distributions recorded for identical laser intensities but for different pulse durations demonstrate unambiguously that a significant fraction of the electrons are emitted in quasithermal processes and results argue strongly against a field ionization or direct multiphoton ionization mechanism. For electron energies above the photon energy, which account for about half the intensity, the whole signal is consistent with this quasithermal emission.