Heidelberg 2015 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 16: Posters 3: Novelties in Molecular Physics
MO 16.6: Poster
Mittwoch, 25. März 2015, 17:00–19:00, C/Foyer
XUV Transient Absorption Spectroscopy of Photochemical Processes — •Lorenz Drescher, Martin Galbraith, Judith Dura, Christopher Smeenk, Marc Vrakking, and Jochen Mikosch — Max-Born-Institut, Berlin, Germany
The exact position of atomic inner-shell absorption edges depends sensitively on the atom’s chemical environment. Chemical shifts hence allow to identify specific sites in a molecule with absorption spectroscopy. Ultrashort, spectrally broad XUV pulses from High Harmonic Generation offer the intriguing opportunity of transient absorption studies with unprecedented time resolution. It is anticipated that this will allow to access electronic and nuclear dynamics in molecules down to a few-femtosecond and even attosecond timescale from a site-specific point of view. Here we use this novel technique to study one of the reference standards of femtochemistry, the photodissociation of methyiodide: CH3I + hν —→ CH3 + I. The excitation of a single state in the A-band of CH3I leads to a dissociation into CH3 and both I(2P3/2) and I*(2P1/2) within 60-120 fs. This involves internal conversion at a non-adiabatic intersection within the first 20 fs after the Frank-Condon region [1]. Such fast time scales are a challenge for traditional femtochemistry experiments. We are also working on creating isolated attosecond pulses, which would pave the way to studying purely electronic dynamics in molecules with transient absorption. [1] Hammeric et al., J. Chem. Phys. 101, 5623 (1994), Corrales et al., Nature Chemistry 6, 785-790 (2014)