a-C:H:N films were studied by time-resolved photoluminescence (PL) spectroscopy. It was shown that, on the one hand, the increasing of nitrogen content in gas mixture leads to a dramatic increase of PL intensity and to downshift of the main PL band. On the other hand, in PL spectra measured from the lateral face of the films the significant narrowing of the PL bands was observed. (C) 2000 Elsevier Science Ltd and Techna S.r.l. All rights reserved.