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Universal molecule injector in liquid helium: Pulsed cryogenic doped helium droplet source
 

Summary: Universal molecule injector in liquid helium: Pulsed cryogenic doped
helium droplet source
V. Ghazarian, J. Eloranta, and V. A. Apkariana)
Department of Chemistry, University of California, Irvine, California 92697
Received 17 May 2002; accepted for publication 10 June 2002
Progress toward the construction of a universal molecule injector for doping bulk liquid helium is
reported. A pulsed valve that operates at cryogenic temperatures, down to 4 K, is demonstrated
within the confinement of a cryostat, operating in the vapor above a steady level of liquid He. The
insulated valve can be operated at elevated temperatures with preseeded helium gas in supersonic
expansion mode, as demonstrated through laser-induced fluorescence spectra of seeded NO2 . At
cryogenic operating temperatures, the expansion into vapor helium produces a well-collimated
liquid helium droplet beam, which is then used to transfer to the liquid impurities produced by laser
ablation from a cryogenic rotating target. The operation can be visualized using copper as the
ablation target: the droplet beam is imaged via Rayleigh scattering, while the beam past the plasma
is imaged by the fluorescence of the entrained Cu atoms. The beam drags along copper ions and
electrons, the recombination of which controls the fluorescence yield downstream. 2002
American Institute of Physics. DOI: 10.1063/1.1505662
I. INTRODUCTION
Investigations of spectroscopy, chemistry, and dynamics
of molecular species in superfluid helium are the subjects of

  

Source: Apkarian, V. Ara - Department of Chemistry, University of California, Irvine

 

Collections: Chemistry