Ejection of excimers from the surface of solid argon upon exciton self-trapping

Molecule emission from condensed Ar and O 2 targets by 750 eV Ne impact

“…These excitons can be trapped in the bulk or at the surface as atomic self-trapped excitons, Ar à , or as molecular excitons, Ar à 2 . The ejection of an Ar à 2 dimer (and also of Ar à ) from the surface is associated with the formation of a so-called cavity around Ar à 2 localized near the surface [45][46][47]28,6]. The repulsive forces needed to create this cavity lead to the ejection of the enclosed molecular excimer.…”

“…We presume that the reason hereto is provided by a contribution of electronic sputtering to dimer emission at energies of around 0.1 eV. As detailed in Appendix B, strongly bound molecular excitons, Ar à 2 , may be ejected from the solid; previous experiments (with MeV He + ion irradiation) [6] and molecular-dynamics simulations [28] showed that these are emitted with energies of around 0.1 eV. Our molecular-dynamics simulations do not include this emission mechanism.…”

“…This mechanism was confirmed by studies of the luminescence produced by MeV light ions [45], low-energy electrons [6] and photon excitation [46] of solid argon. The ejection of excimers from solid argon upon exciton self-trapping was investigated also in molecular-dynamics simulations [28]. In these simulations -performed for various crystal surfaces -the kinetic energy of the ejected dimers was well below 0.1 eV [28].…”

“…The ejection of excimers from solid argon upon exciton self-trapping was investigated also in molecular-dynamics simulations [28]. In these simulations -performed for various crystal surfaces -the kinetic energy of the ejected dimers was well below 0.1 eV [28]. Experiments performed inducing the electronic excitation by MeV He + ions investigated the spatial and temporal characteristics of the dimer luminescence bands and found that the average kinetic energy of the desorbed Ar à 2 is around 0.1 eV but ranges as low as 0.06 eV for dimers in highly vibrationally excited states [6].…”

Desorption of excimers from the surface of solid Ne by low-energy electron or photon impact

“…Molecular-dynamics calculations by Johnson and coworkers have shown that the desorption of excited dimers was energetically possible for Ar 2 * in 1,3 ⌺ u states 8 and for Kr 2 * in a 1 ⌺ u state. 9 They pointed out that the excimer desorption was related to the formation of a ''cavity'' around a molecular-type self-trapped exciton as in the atomic desorption case.…”