Enhanced Electron Attachment to Rydberg States in Molecular Hydrogen Discharges
We present recent experimental results on negative ion formation via electron attachment to highly-excited molecules and explore the role of high-Rydberg (HR) states of H{sub 2} and H{sub 3} in negative hydrogen volume sources. Even though electron attachment to high-vibrational (HV) states of H{sub 2} has been generally considered to be the major H{sup -} formation mechanism, recent studies by others have shown that, (i) the measured H{sup -} ion densities in volume H{sub 2} discharges cannot be accounted for by this mechanism alone, and (ii) the H{sup -} ion temperatures in volume sources are higher than those expected from electron attachment to HV states. We will show that H{sup -} formation via electron attachment to HR states (together with electron attachment to HV states) can account for both those observations. Possible mechanisms for the formation of these excited states are discussed, including the formation of long-lived, core-excited Rydberg states. Experimental evidence for negative ion formation via electron attachment to core-excited Rydberg states in a glow discharge apparatus is presented.
- Research Organization:
- Oak Ridge National Lab., Oak Ridge, TN; University of Tennessee, Knoxville, TN (US)
- Sponsoring Organization:
- USDOE Office of Environmental Management (EM) (US)
- OSTI ID:
- 839050
- Country of Publication:
- United States
- Language:
- English
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