Bulk and surface excitons in solid neon

Transmission and reflection spectra of solid neon in the valence-exciton range ($16\le h\nu \le 22$ eV) have been carefully reinvestigated using highly monochromatized ($\Delta E=4\mathrm{}$ meV) synchrotron radiation. A surface-exciton state at $h\nu =17.15\mathrm{}$ eV located 210 meV below the $n=1\mathrm{}$ ($j=\frac{3}{2}$) bulk exciton is observed and unambiguously identified. Energy positions of the bulk exciton states and line shapes as well as new and more precise values for derived quantities have been determined and are discussed in view of recent theoretical predictions. For the first time we are able to resolve the spin-orbit splitting of the $j=\frac{3}{2}$ and $j=\frac{1}{2}$ states and study the influence of exchange interaction. The value of 90 meV for the spin-orbit splitting is close to the gas-phase result. Within a quantum-defect approach we evaluate a new band gap of 21.58 eV for solid Ne.