Excitation-induced processes in model molecular solid – N₂

Recent findings on electronically induced processes in N₂ molecular solids monitored by luminescence methods are presented with a focus on the electronically induced desorption. Low-energy electron beam was used for excitation to avoid the knock-on defect formation and sputtering. The samples were probed with depth by varying electron energy. VUV photon emissions from desorbing N^* atoms (the ⁴P_1/2–5/2→⁴S_3/2 transitions) under irradiation by electrons of subthreshold energy were observed for the first time. Their distinctive feature is a coincidence with the gas phase lines within the experimental error. New data on electronically stimulated desorption of N₂^* molecules in the electronic excited state C³Π_u are reported. Monitoring of nonstationary desorption NsD in combination with the detection of thermally stimulated exoelectron emission TSEE and post-desorption reveal the contribution of charge recombination reactions in the electronically induced particles ejection. Fresh approach to study of electronically induced desorption opens new type of greatly delayed desorption associated with the entry of freeing electrons in recombination process. - Highlights: • Electronically induced processes in solid N₂ were studied with a focus on the electronically induced desorption. • Yields of excited particles desorption was monitored with luminescence spectroscopy. • The electronic desorption of nitrogen atoms in the ⁴P_1/2–5/2 state was detected for the first time. • Comparative study of nonstationary desorption, thermally stimulated exoelectron emission TSEE and post-desorption was performed. • Essential role of charge recombination in the electronically induced desorption was established.