Electron-stimulated field desorption of diatomic and triatomic hydrogen

Precursor structures of high-energy ${\mathrm{H}}_2^{+}$ and ${\mathrm{H}}_3^{+}$ field ions have been detected by retarding-potential analysis, and the electron-stimulated field desorption of adsorbed ${\mathrm{H}}_2$ and ${\mathrm{H}}_3$ is proposed as the most plausible origin. From energy distributions of electron-stimulated field desorbed ${\mathrm{Ne}}^{+}$ and field desorbed ${\mathrm{H}}_3^{+}$, taken on W(111) at the same field strength and surface temperature, we infer the presence of a linear ${\mathrm{H}}_3$ adsorbed in an upright position on the field emitter surface.