Spontaneous emission from the C3 radical in carbon plasma

Spontaneous emission measurements are discussed for the Swings transitions of the C3 radical in laser-generated graphite plasma, and the spectroscopy of the C3 radical in carbon vapor and plasma is summarized. A review is given of some theoretical calculations and emission spectroscopic investigations are presented. Time-averaged, laser-induced optical breakdown spectra are reported from Nd:YAG laser generated graphite microplasma. In 200-300 Torr of argon and helium, and depending on the specific experimental configuration, a weak emission continuum is observed centered at 400 nm when using a laser fluence of typically 1 J/cm2. Such continua were not detected in our previous experiments using focused laser radiation. The possibilities for the origin of this continuum are considered.