M.Sc. Marco Kapitzke - doctoral student
0'304 (HU office/lab)
My Ph.D. research investigates ultrafast electron dynamics of advanced materials. Currently, I am interested in the charge carrier and exciton dynamics of molecular dyes and transition metal dichalcogenide (TMDC) monolayers.
Especially TMDC's have attracted exceptional scientific and technological enthusiasm, since their excitonic features facilitate new and exciting optoelectronic applications. The complete non-equilibrium carrier dynamics of TDMCs have already been scrutinized by ultrafast pump-probe (transient absorption and reflectivity) experiments. However, abundant phenomena are probed simultaneously in this spectroscopy, often displaying overlapping resonances with miscellaneous dynamics. To this date, an ambiguous measurement of the ultrafast exciton dynamics in TMDC monolayers is still lacking.
Time-resolved photoluminescence (TRPL) spectroscopy allows the uncoupling of the dynamics observed in pump-probe spectroscopy because exclusively radiative recombination channels are monitored. Unfortunately, conventional TRPL techniques lack the time resolution (several ps) to observe the ultrafast dynamics in TMDCs shortly after photoexcitation.
Our research aims to resolve the ambiguity of the existing pump-probe spectra by employing broadband fluorescence upconversion spectroscopy (FLUPS). It achieves a time resolution comparable to the pulse duration (~100 fs) and is thus the ideal complementary technique to study TMDC monolayers. In our lab, we are currently developing a FLUP spectrometer following N. P. Ernsting's design.