Amplification of vacuum ultraviolet radiation by reflection on planar and corrugated aluminum films containing helium excimers

Alpha particles accelerated towards a flat Al sample accumulate and precipitate in the form of dense He bubbles. Under fast-electron bombardment, these bubbles have been observed to generate He excimer molecules which decay by emitting vacuum-ultraviolet (VUV) fluorescent radiation. The calculation of the VUV dielectric function and reflectance shows that a thin planar film made of such He–Al composite and driven out of equilibrium can generate amplifying reflection. This phenomenon occurs at specific isolated frequencies and incidence angles when the excimer concentration in the pressurized fluid of the bubbles becomes sufficient. By use of analytical and numerical multiple-scattering simulations, the expected gain of this VUV amplifying mirror is studied, and the possible improvement brought about by shaping the film into a periodic array of adequately adjusted microresonators is demonstrated.