Electron Impact Excitation of Adenine in the VUV.

Dissociative excitation of adenine (C$_{\mathrm{6}}$H$_{\mathrm{5}}$NH$_{\mathrm{2}})$ into excited atomic fragments has been studied in the electron impact energy range from threshold to 300 eV. A crossed beam system coupled to a vacuum ultraviolet (VUV) monochromator is used to study emissions in the wavelength range from 110 to 200 nm. The beam of adenine vapor from a stainless steel oven is crossed at right angles by the electron beam and the resultant VUV radiation is detected in a mutually orthogonal direction. Excitation of H Lyman-$\alpha $, the strongest feature in the spectrum, is considered in detail.