Control Schemes for Laser Driven H-atom Switching in the Condensed Phase
During the last decade different schemes for controlling chemical reactions by means of tailored laser pulses have been developed. While most of the theoretical and experimental work done so far deals with isolated molecules in the gas phase it is challenging to investigate these ultra fast dynamical processes under condensed phase conditions. There the laser control is counteracted by energy dissipation processes which tend to move the system into thermal equilibrium.

In the present work we study the ultra fast photoisomerization dynamics of intramolecular hydrogen transfer systems. We will show how different schemes for controlled hydrogen switching perform in the presence of dissipation. The hydrogen transfer is modelled in terms of a low dimensional system weakly coupled to a Markovian heat bath. For the energy surface along the reaction co-ordinates we use model potentials with parameters adjusted to (ab initio) data obtained for different molecules (e.g. malonaldehyde derivatives). The dynamics on these potential surfaces is simulated using density matrix theory. Among the control schemes we investigate are the pump-dump approach and different variants of the recently proposed "hydrogen subway" scheme for tunnelling control.