New DFG grant:

Control of chemical reactions via the carrier envelope phase of ultra-short laser pulses

Investigations aimed at the control of photochemical processes have received enormous attention over the last ten years. Here, we can distinguish two different approaches, one in the frequency domain (high spectral resolution, in general continuous wave), a second in the time domain (ultra-short laser pulses). Both approaches rely on the importance of the phase of the electromagnetic laser radiation or the molecular wave functions induced by it.

A new grant by the Deutsche Forschungsgemeinschaft now allows the Weitzel group to investigate the influence of the carrier envelope phase (CEP) of a few-cycle laser pulse on the molecular fragmentation of chemical compounds. The goal of the project is to develop a concept for the control of chemical processes. In particular we hope to gain insight into the coupling of electron and nuclear dynamics and thus into the limits of the Born-Oppenheimer approximation. The latter is one of the holy grails in physical chemistry. Ultimately the project may be expected to provide completely new information on the dynamics of chemical process, which may affect the entire field.

The central part of the new technology is a special femtosecond laser with pulse duration shorter than 15 femtoseconds. In contrast to most systems on the market, this laser allows to keep the phase between the carrier wave and the intensity envelope, hence carrier envelope phase, constant and even allows to set it to a desired value.

The grant by the DFG covers approximately 300 000,- Euro.

References:
M.V. Korolkov, K.-M. Weitzel, Chem. Phys.,  338, 277-284, (2007)
Laser pulse control of photofragmentation in DCl⁺: the effect of carrier envelope phase
http://dx.doi.org/10.1016/j.chemphys.2007.03.007

K.-M. Weitzel, ChemPhysChem, 8, 213-215, (2007)
Controlling the electrons provides means for controlling chemistry (Highlight)
http://dx.doi.org/10.1002/cphc.200600641