Production and characterization of an intense hyperthermal beam of H3 molecules and of H atoms

In order to study the reaction H + H2 in a crossed molecular beam experiment, a means of generating an intense beam of H atoms is essential. The method consists of using a high power arc discharge to create a high temperature (approx.12,000 K) plasma in which H2 molecules can be dissociated into atoms. By using an arc source of the type developed by Kunth, a stable, intense, hyperthermal H atom beam was successfully produced. Section 2 of this thesis discusses the design and operation of the apparatus and Section 3 of the thesis discusses the characterization of the hydrogen atoms within the beam. The laboratory energy distribution function of these atoms was determined approximately, and spans the range from 0.5 eV to about 12 eV. The total intensity of this beam is of the order of approx.1022 atoms/sterad/sec. In the course of developing this intense beam of hydrogen atoms, the source was found to also produce metastable H3 molecules. This is the first direct, unambiguous observation of such a species in a molecular beam, and is discussed in Section 4. Translational energy analysis of this H3 molecule indicates an energy distribution similar to that of the H atoms, suggesting that the lifetime of H3 is of the order of 40 μsec or longer. The author also observed emission spectra from the Rydberg states of H3 identified previously by Herzberg. This is spectroscopic evidence for the presence of this neutral molecule in the beam