Title: Reassessing Graphene Absorption and Emission Spectroscopy,
Abstract: We present a new paradigm for understanding optical absorption and hot
electron dynamics experiments in graphene. Our analysis pivots on assigning
proper importance to phonon assisted indirect processes and bleaching of direct
processes. We show indirect processes figure in the excess absorption in the UV
region. Experiments which were thought to indicate ultrafast relaxation of
electrons and holes, reaching a thermal distribution from an extremely
non-thermal one in under 5-10 fs, instead are explained by the nascent electron
and hole distributions produced by indirect transitions. These need no
relaxation or ad-hoc energy removal to agree with the observed emission spectra
and fast pulsed absorption spectra. The fast emission following pulsed
absorption is dominated by phonon assisted processes, which vastly outnumber
direct ones and are always available, connecting any electron with any hole any
time. Calculations are given, including explicitly calculating the magnitude of
indirect processes, supporting these views.