The emission bands of the NO molecule excited in an impure afterglow were studied in the vacuum ultraviolet region. The abrupt cutoff at a certain v' value was observed in the {j, 'Y, and Il bands and also the nonappearance of the E, and {j' bands was confirmed. An explanation for these observations was attempted in connection with the dissociation energy of the NO molecule and with the mechanism of the afterglow. 10 Y. Tanaka, J. Sci. Research Inst. (Tokyo) 43, 28 (1949). 80 75 701 J 65 15 M. Brook, Scientific Report No.2, Institute of Geophysics, University of California (March, 1953); J. Kaplan and M. Brook (private communication). 16 G. Cario and L. Reinecke, Abhandl. braunschweig. wiss.