Intensity Inversion in the Balmer Spectrum ofC5+

Abstract

Intensity inversion between the first (3→2) and second (4→2) Balmer series spectral lines of ${\mathrm{C}}^{5+}$ ions has been observed during plasma expansion into a buffer gas. Numerical modeling indicates that the Balmer spectrum is consistent with the Lyman spectrum and with charge-transfer pumping of the $n=4\mathrm{}$ level. Electron-ion recombination alone is insufficient to explain the observed intensity distribution.