CD-MPI: Two color multi photon ionization of chiral ketones

PHYS 556

Alexander Bornschlegl,, Ulrich Boesl,, and Christoph Logé. Chemistry Department / Physical Chemistry 1, Technical University Munich, Lichtenbergstr. 4, D-85748 Garching, Germany
The nπ* transition of cyclic carbonyls is well known for its strong relative circular dichroism (CD). Δε/ε can reach values in the per cent regions. By using left and right circularly polarized laser light for excitation and ionization it is possible to detect CD in ion yield during multi photon ionization (MPI) processes. Through coupling this ionization method with a time of flight mass spectrometer (TOFMS), mass resolved CD spectroscopy becomes possible. This work presents such measurements employing different excitation/ionization pathways and compares the results. Our experiments provide evidence, that there is an accumulation of the CD effects of different involved transitions. The simplest investigated ionization pathway is the one color MPI via the π* and 3d Rydberg state of 3-MCP (1+1+1). A second investigated scheme is the two color (1+1') MPI. Both methods yield a different CD in ion yield.

General Posters
7:30 PM-10:00 PM, Wednesday, March 28, 2007 Hyatt Regency Chicago -- Riverside Center, Poster

Division of Physical Chemistry

The 233rd ACS National Meeting, Chicago, IL, March 25-29, 2007