Exciton Dispersion and Electronic Excitations in hcpH4e

D. A. Arms, R. O. Simmons, M. Schwoerer-Böhning, A. T. Macrander, T. J. Graber
2001 Physical Review Letters  
We present first measurements of the dispersion of excitons in solid helium, taken on a single hcp 4 He crystal along the c axis. In agreement with studies on helium clusters, the major energy-loss peak can be interpreted as an intermediate molecular-type exciton, as we do not observe Wannier-like excitations. The measurements are in the (0 0 2) periodic zone, with the exciton energy dispersing along the c axis with a minimum at the G point. A calculated conduction band minimum at 31.0 eV above
more » ... um at 31.0 eV above the valence band at G is supported by our data at energies above the exciton energy, leading to an exciton binding energy of 8.4 eV.
doi:10.1103/physrevlett.87.156402 pmid:11580715 fatcat:lhwidghnjvehnimysqcogw7j2m