High resolution EUV emission spectroscopy of the N2 c′ 1Σu+ υ′=3 and 4 levels by electron impact

A high resolution 36 m Angstrom (FWHM), optically thin emission study of the N-2 c' (1) Sigma(u)(+)(4, 3) and (3,2) Rydberg bands excited by electron impact at 100 eV has been completed in the extreme ultraviolet (EUV). A model of the perturbed rotational line intensity distribution of the bands shows the effects of electronic state mixing between the c' (1) Sigma(u)(+) Rydberg state and the b' (1) Sigma(u)(+) valence state. By normalizing the model to the published predissociation yield for J' = 9 the laboratory spectrum can be used to determine the predissociation yields for each rotational level of v' = 3 and 4. Based on a 25% accuracy of the model fit to the measured signal intensities it is found that the predissociation yields of the c', v' = 4 rotational levels increase as the percentage of b' (1) Sigma(u)(+) character increases. On the other hand, the predissociation yields of the cl, v' = 3 rotational levels reach a maximum for 5 < J' < 10. The mean predissociation yields for c', v' = 3 and 4 levels are a function of temperature and are found to be 0.41 and 0.58, respectively at 300 K. The J'-dependent predissociation yields indicate that the emission cross section is a function of temperature. The remainder of the bands forming the v " progressions (v " = 0-5) from v' = 3 and (v " = 0-6) from v' = 4 were studied at 64 m Angstrom (FWHM) resolution. Using this composite spectrum of the two progressions the electron impact emission cross sections of the N-2 c', v' = 3 and 4 levels at 300 K were determined and compared with previous results.