We show unequivocal evidence for formation of He_{2}^{*} excimers in liquid He II created by ionizing radiation produced through neutron capture. Laser beams induce fluorescence of the excimers. The fluorescence is recorded at a rate of 55.6 Hz by a camera. The location of the fluorescence is determined with an uncertainty of 5 μm. The technique provides an opportunity to record the flow of He_{2}^{*} excimers in a medium with very small viscosity and enables measurement of turbulence around macroscopic liter size objects or vortex matter in three dimensions.
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Imaging Fluorescence of He_{2}^{*} Excimers Created by Neutron Capture in Liquid Helium II.
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Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA.
We show unequivocal evidence for formation of He_{2}^{*} excimers in liquid He II created by ionizing radiation produced through neutron capture. Laser beams induce fluorescence of the excimers. The fluorescence is recorded at a rate of 55.
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