Fundamental plasma processes of negative ions in a low pressure region (a gas pressure P
g < 1.5 Pa) have been studied using the photodetachment technique and vacuum ultraviolet (VUV) spectroscopic measurements in the spectral range from 100 to 180 nm. Understanding the behavior of a plasma with negative ions, in particular, the correlation between H
- density and vibrationally excited H
2 density, is of great interest in the field of atomic-molecular physics and ion source developments. The volume and the surface effects of negative ions are discussed taking into account the e-V, the E-V, and the RD processes, and the measured VUV spectrum is compared with the synthetic one. The cascade transition to the B
1Σ
+u state by the electron excitation contributes to the production of the highly vibrationally excited levels of the X
1Σ
+g ground electronic state.
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