Photoluminescence spectra of xenon implanted natural diamonds

The natural diamonds were implanted with 500 keV Xe ions within the dose range 1 x 10(13)-5 x 10(14)cm(-2). The post-implantation thermal annealing was carried out gradually at temperatures between 300degreesC and 1400degreesC. Photoluminescence spectra were measured after each annealing step in the temperature range 1.5-200 K. The spectra featured the Xe-related zero phonon line (ZPL) at 811.6 run (1.527 eV) and a vibronic sideband with several quasilocal and phonon peaks. The Huang-Rhys factor was-determined to be exp(-S)=0.5+/-0.1. The ZPL at 1.5K is inhomogeneously broadened and has line width in the range 5.5-15 cm(-1) depending on the implantation dose. It was concluded that the vacancy is involved in the Xe center formation. The photoluminescence is significantly quenched by the irradiation-induced defects. A growth of the second ZPL at 793.3 nm was observed at elevated temperatures. The excited state energy level splitting of DeltaE = 128 +/- 20 cm(-1) was found by studying the temperature behavior of these ZPLs. It was concluded that the excited state, as well as the ground state of the optical transition, has a double level structure, and that ZPL at 811.6 is not, likely, a resonance 0-0 line. (C) 2002 Elsevier Science B.V. All rights reserved.