Detection of boron nitride radicals by emission spectroscopy in a laser-induced plasma

Several vibrational bands of boron nitride radicals have been observed in a plasma produced by pulsed-laser ablation of a boron nitride target in low-pressure nitrogen or argon atmospheres. Using time- and space-resolved emission spectroscopic measurements with a high dynamic range, the most abundant isotopic species (BN)-N-11 have been detected. The emission bands in the spectral range from 340 to 380 nm belong to the Delta nu = -1, 0, +1 sequences of the triplet system (transition A(3)Pi -X(3)Pi). For positive identification, the molecular emission bands have been compared with synthetic spectra obtained by computer simulations. Furthermore, WON emission bands have been reproduced by computer simulation using molecular constants which have been deduced from the (BN)-N-11 constants. Nevertheless, the presence of the lower abundant isotopic radical WON was not proved due the noise level which masked the low emission intensity of the WON band heads. (C) 2001 Elsevier Science B.V. All rights reserved.