Abstract
UV pulses of 100 fs at 340 nm are utilised to excite pyrene to the vibrationally cold S2
state. Population and depopulation processes occurring in the S2 state are investigated
by transient absorption spectroscopy with a white continuum probe. In the first 400 fs
after excitation it is possible to measure the growth and disappearance of a band at
585 nm which is assigned to the S14←S2 transition. As a consequence of the internal
conversion process from S2 to S1 state, the disappearance of the 585 nm band and the
growth of the transient spectrum due to