Optimal control of molecular processes using intense femtosecond (fs) lasers is one of the
hot topics in modern laser science [1]. The goal is to manipulate molecular potential
energy surfaces by the strong laser field, which forces a molecular system into a specific
relaxation pathway. For instance, the possibility of selective bond dissociation and
rearrangement in polyatomic molecules was shown recently [2]. This opens the door to a new
exciting scientific field in photochemistry, which could even have application in biology
or medicine keeping in mind that large molecules mediate fundamental processes in living
organism.
The gain of knowledge by such kind of experiments largely depends on a detailed insight
into the fundamental processes induced, when laser light is focused on large finite
molecules. With their well defined, highly symmetric structure the fullerenes are model
systems acting as interfaces between atoms or small molecules and the solid state. The 60
delocalized pi electrons in the C60 fullerene give rise to interesting but complex
photo-physical processes due to correlation effects and the strong interaction with the
ionic backbone.
In this talk, we present our latest experimental effort using temporally shaped laser
pulses. This is a much appraised technique for controlling and possibly analyzing reaction
pathways in complex systems. Closed feedback loop optimization allows one to find optimal
excitation schemes on potential energy surfaces of very complex systems without prior
knowledge of their structure. We have applied this technique to obtain systematic control
on fragmentation processes in C60.
References:
[1] A. D. Bandrauk, R. J. Gordon, and Y. Fujimura, Laser Control and Manipulation of
Molecules (ACS Symposium Series Vol. 821, Oxford University Press, Oxford, 2002)
[2] R. J. Levis, G. M. Menkir, and H. Rabitz, Science 292, 709 (2001)