title: Observation of excitonic N-body bound states: polyexcitons in diamond.
abstract: We have found a series of resonances associated with the bound state (polyexcitons, PE(N)s) of N excitons up to N=6 in the emission spectra of diamond under two-photon excitation at around 10 K. Time-resolved spectra show a stepwise formation of PE(N)s with smaller to larger N, as well as a successive decay from larger to smaller N. At higher excitation levels, the transformation of PE(N)s into a condensed phase of electron-hole droplets occurs. The binding energies of the PE(N)s, normalized to the exciton Rydberg energy, agree well with those of silicon, suggesting the universality of the phenomena.
authors.affiliation: Photon Science Center, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Omachi
authors.forename: T
authors.initials: T
authors.lastname: Suzuki
authors.forename: K
authors.initials: K
authors.lastname: Kato
authors.forename: N
authors.initials: N
authors.lastname: Naka
authors.forename: K
authors.initials: K
authors.lastname: Yoshioka
authors.forename: M
authors.initials: M
authors.lastname: Kuwata-Gonokami