Both ions and neutral radicals are potential stepping-stones between the hydrogen-dominated chemistry of diffuse clouds and the complex organic chemistry observed in dense star-forming regions. We use plasma discharge to prepare these ions and radicals so that we can do laboratory spectroscopy on them.
In our laboratory, we have two plasma sources: a hollow cathode,
and a supersonic expansion source.
Our liquid-nitroge-cooled hollow cathode, based on the design of T. Amano ,
is an efficient discharge source to produce positive ions,
especially protonated species.
The copper cathode is housed in a PVC cell where appropriate
precursor gases can flow continuously through.
A high voltage source is then coupled to an anode, positioned
halfway along the length of the cathode, and the resultant discharge
produces a plasma that fills the length of the cathode tube.
We intend to study important protonated ions in the ISM ion
chemistry such as the floppy H5
The supersonic expansion source, based on the design of M. C. McCarthy , arcs through the starting of a supersonic molecular beam. This source is versatile in producing neutral molecules, radicals, ions and molecular complexes.
 T. Amano, J. Opt. Soc. Am. B, 2, 790 (1985).
 M. C. McCarthy et al., Astrophys. J. Suppl. 129, 611 (2000).