The charge carrier dynamics of photoexcited bismuth generates a Drude response that evolves over time. Our data shows that the plasma frequency of bismuth displays an initial increase and a subsequent decay. We have performed ab initio calculations on bulk bismuth within the density functional theory, and show that this peculiar behaviour is due to local extrema in the valence and conduction bands. It follows that most of the carriers first accumulate in these extrema, and reach the Fermi level only 0.6 ps after the photoexcitation.
The original publication is available by link DOI: 10.1103/PhysRevB.85.155139