Crossed beam photodissociation imaging of HeH+ with vacuum ultraviolet free-electron laser pulses.
Molecular photofragmentation has been studied by event imaging on HeH+ ions at 32 nm (38.7 eV) in a fast ion beam crossed with the free-electron laser in Hamburg (FLASH), analyzing neutral He product directions and energies. Fragmentation into He(1snl,n > or = 2)+H+ was observed to yield significant photodissociation at 32 nm with an absolute cross section of (1.4+/-0.7) x 10(-18) cm2, releasing energies of 10-20 eV. A clear dominance of photodissociation perpendicular to the laser polarization was found in contrast to the excitation paths so far emphasized in theoretical studies.
Max-Planck-Institut für Kernphysik, D-69117 Heidelberg, Germany. hendrik.pedersen@mpi-hd.mpg.de
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Pedersen
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Altevogt
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Jordon-Thaden
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Heber
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Rappaport
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Schwalm
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Ullrich
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Zajfman
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Treusch
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Guerassimova
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Martins
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Hoeft
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Wellhöfer
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Wolf