Papers by Keyword: Ionization Energies

Abstract: 8H-SiC epilayers grown on small 8H-SiC Lely platelets are investigated optically using photoluminescence spectroscopy. At low temperature the near band gap emission detected in the 2.78 to 2.67 eV range contains sharp lines associated to nitrogen-bound-exciton recombination. Three different no-phonon lines are detected accompanied by their phonon replicas. Free-exciton replicas are also observed which allows the determination of the excitonic band gap. The binding energy of the bound excitons can thus be determined and the ionization energies of the three nitrogen levels in 8H-SiC are estimated and found to be rather shallow compared to the values for other hexagonal polytypes. Additional bound-exciton lines are observed when the experimental photoluminescence temperature is increased.

Abstract: A new diatomic molecule-containing endohedral fullerenes were prepared by ion implantation technique (introducing negatively charged C70 into a low temperature lithium plasma column by a strong exial magnetic field).The species prepared were Li@C70 and Li2@C70 and ionized by surface ionization. Their existance was demonstrated through high sensitivity, magnetic mass spectrometer. The corresponding endohedral ions undergo the Rice shrinkwrap mechanism: a mass –analyzed ion spectrum demonstrates the loss of a C2 unit from the cage. The observed ionization energies of endohedral molecules were 5.1 " 0.1 eV and 5.3 " 0.1 eV, respectively.