Crossed Beam Photodissociation Imaging of HeH+ with FLASH pulses (July 2007)

Experiment at FLASH

Time of flight and position of the observed fragments. The colors (from blue to red) indicate the frequency of occurence. A clear dominance of photodissociation perpendicular to the laser polarization was found.

(Credit: MPG Heidelberg Press release)

Scientists from the Max Planck Institute for Nuclear Physics in Heidelberg, their collaborators from DESY, from the Weizmann Institute of Science (Israel), and the University of Hamburg reported on results from a first path-finding crossed beams imaging experiment at FLASH on the photodissociation of HeH+ at 32 nm, detecting events leading to neutral He fragments and analyzing the kinetic energy release and the angular orientation of the dissociating molecule with respect to the photon polarization.

The experiment uses a pulsed mass-selected monoenergetic ion beam at several
keV laboratory energy and an ion-photon interaction zone kept under UHV. From the energy releases measured with three-dimensional reaction imaging they found significant contributions of highly excited product states with He(1snl) with n>=3 and the angular analysis reflects excited molecular states they determined the absolute cross section.

A clear dominance of photodissociation perpendicular to the laser polarization was found in contrast to the excitation paths so far emphasized in theoretical studies.

Their results appeared in Physical Review Letters (June 2007).

(from: ...Paper and Press release)

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