High resolution EUV emission spectroscopy of the and 4 levels by electron impact

Abstract

A high resolution 36 mÅ (FWHM), optically thin emission study of the 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 Rydberg state and the valence state. By normalizing the model to the published predissociation yield for the laboratory spectrum can be used to determine the predissociation yields for each rotational level of 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 rotational levels increase as the percentage of character increases. On the other hand, the predissociation yields of the rotational levels reach a maximum for . The mean predissociation yields for and 4 levels are a function of temperature and are found to be 0.41 and 0.58, respectively at 300 K. The -dependent predissociation yields indicate that the emission cross section is a function of temperature. The remainder of the bands forming the progressions -5) from and -6) from were studied at 64 mÅ (FWHM) resolution. Using this composite spectrum of the two progressions the electron impact emission cross sections of the and 4 levels at 300 K were determined and compared with previous results.