OPTICAL MODULATION OF BULK ONE-PHONON STATE IN DIAMOND

Infrared absorption and electron spin resonance measurements have been performed in nitrogen-containing mixed-type diamonds under several il lumination conditions. It has been observed that bulk one-phonon absor ption spectra are modulated by illumination of higher than 2.0 eV in p hoton energy and the change recovers within a few hours after the exci tation light is turned off. The results are explained by the change in the charge state of isolated nitrogen, and a characteristic absorptio n band created by the positive charge state of isolated nitrogen (N+) is proposed. This phenomenon is applicable in decomposing the infrared absorption spectra of diamonds into each component, which contain inf ormation about the type and concentration of nitrogen aggregate. (C) 1 998 American Institute of Physics. [S0003-6951(98)03736-X].