The 'cathedral' in the near-threshold absorption spectrum of N2

The absorption spectrum of N2, just above the ionization limit, in the energy region between 125-bar 750 and 126-bar 600-bar cm-1, is dominated by two broad features which have the appearance of the towers of a 'cathedral'. Recently, this energy region has been measured by Sommavilla et al. and an assignment for one of these two bands has been proposed as the v=44 level of the b'1Σu+ valence state. In order to discuss this assignment, we have solved the coupled-channel Schrodinger equation for determining the high vibrational levels of b'. Furthermore, from a study of the autoionization widths, we suggest as assignment the Rydberg state (A2Πuv+=1) 3dσg1Πu