Photoluminescence excitation and quenching spectroscopy techniques were app
lied to the red band, and the 1.68, 1.945 and 2.156 eV lines in chemical va
pour deposition diamond films. Ground state positions for the 1.68, 1.945 a
nd 2.156 eV centers are found as E-C -2.1, -2.0 and -2.8 eV, respectively.
Interpretation of the 1.945 and 2.156 eV centers as [N-V](-) and [N-V](0) d
efect states is supported. (C) 1999 Elsevier Science S.A. All rights reserv
ed.