Modification to thermal emissions by clusters on their own metallic surface

Abstract

The permanent presence of clusters on their own solid surface is shown to modify particle emission. These modifications affect atom/molecule emission, electron emission, and photon emission from pure metallic surfaces at a vacuum interface. Data for refractory metals, particularly for tungsten, are scrutinized for effects from these bound clusters, or Maxwell–Boltzmann (MB) particle aggregates, which do not exhibit a crystalline structure but are nevertheless part of the surface. It is shown that the so-called work function temperature dependence can be alternatively accounted for by the presence of MB emission sites, and that the descriptions of mass evaporation and radiant heat emission are refined. In the case of photon emission, a complementary gas-like line radiation emerges when measurements and the classical free-electron theory in the near-infrared and visible range are examined in the context of our postulate. Actual observations of individual particle behavior on pure surfaces are enumerated, and a theoretical backup for the predicted area ratio of MB sites to total sites is given.