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arXiv · 0910.4473

First evidence of transient interactions between $π\toπ^*$ optical excitations and image potential states in graphite

M. Montagnese·S. Pagliara·S. Dal Conte·G. Galimberti·G. Ferrini·F. Parmigiani
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Abstract

Here we report the experimental evidence of the interactions between the excitations of the $π\toπ^*$ optical transition and the image potential states (IPS) of highly oriented pyrolitic graphite (HOPG). By using non-linear angle resolved photoelectron spectroscopy (NL-ARPES) we show that the IPS photoemission intensity, the effective mass, and the linewidth exhibit a strong variation when the photon energy is tuned across the $π\toπ^*$ saddle points in the 3.1 - 4.5 eV photon energy range. A model based on the self-energy formalism is proposed to correlate the effective mass and the linewidth variations to transient many body effects, when a high carriers density (in the $10^{20}$ cm$^{-3}$ range) is created by the absorption of a coherent light pulse. This finding brings a clear evidence of a high IPS-bulk coupling in graphite and opens the way for exploiting the IPS as a sensitive, nonperturbing probe for the many-body dynamics in materials.

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M. Montagnese, S. Pagliara, S. Dal Conte, G. Galimberti, G. Ferrini, F. Parmigiani. 2009-11-16. First evidence of transient interactions between $π\toπ^*$ optical excitations and image potential states in graphite. https://arxiv.org/abs/0910.4473

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