Stuttgart 2012 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 21: Poster 3: Cluster, Collisions, Energy Transfer, Photochemistry, Spectroscopy in He-Droplets

MO 21.18: Poster

Donnerstag, 15. März 2012, 16:30–19:00, Poster.IV

Experimental calibration of a 3D Velocity map imaging setup using HBr photodissociation — •Mikhail Poretskiy, Maik Veckenstedt, Christof Maul, and Karl-Heinz Gericke — Institute für Physikalische und Theoretische Chemie, Braunschweig, Deutschland

To solve the problem of the overlap of laser beams in space the HBr photodissociation can be analyzed. In a one color experiment HBr is photolyzed at a wavelength of 243.12 nm, which is also used for [2+1]-REMPI of resulting H-atoms. The distribution of the velocity vector of the produced H atoms is presented by two concentric spheres, which correspond to two channels of measured H atoms, which are different due to the spin orbit state of the bromine partner fragment Br and Br*. In two color experiment the fact that HBr can be photolyzed both at the REMPI detection wavelength 243.12 nm and at 193 nm (excimer laser) was used. The H atoms produced by both wavelengths are subsequently ionized only by 243.12 nm radiation. As a result two new channels of H atoms are observed in the velocity distribution by new spheres, which are sensitive to the position of the excimer laser beam. The position of the excimer laser beam is changed until it is overlapped with the beam of dye laser. In case of the overlap of both laser beams in space the spheres, which appears in two color experiment have to be concentric with these from the one color experiment.