Hamburg 2009 – scientific programme

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MO: Fachverband Molekülphysik

MO 21: Photochemie 2

MO 21.3: Talk

Thursday, March 5, 2009, 14:30–14:45, VMP 6 HS-G

Photodissociation dynamics by means of a revised version of velocity-map ion-imaging — •Andreas Schmaunz, Uwe Kensy, Alkwin Slenczka, and Bernhard Dick — University of Regensburg, Regensburg

Velocity-map ion-imaging [1] as a refined version of ion-imaging [2] provides the full three-dimensional velocity distribution of an atomic fragment produced via photolysis of a molecule. The velocity distribution reveals the kinetic and internal energy of the counter fragment. Thus, the full dynamic of the photodissociation is obtained. In the case of a molecular fragment the analysis of the full dynamics requires the measurement of an ion-image for each of the energetically accessible internal states. This procedure is extremely time consuming if not impossible due to the spectral overlap. We present a new technique, a hybrid of real-time ion-counting [3] and REMPI spectroscopy. It allows to obtain the angular and velocity distribution for the entire set of internal states of the molecular fragment within the time necessary to record a common REMPI spectrum. The method will be demonstrated for the photolysis of NO₂ by recording the NO fragment. These data provide insight into the dissociation dynamics far beyond conventional data reported on this system so far.

[1] A. T. J. B. Eppink and D. H. Parker, Rev. Sci. Instrum. 68, 3447 (1997). [2] D. W. Chandler and P. L. Houston, J. Chem. Phys. 87, 1445 (1987). [3] B. Y. Chang, R. C. Hoetzlein, J. A. Mueller, J. D. Geiser, and P. L. Houston, Rev. Sci. Instrum. 69, 1665 (1998).