CN and C2 formation mechanisms in fs-laser induced breakdown of nitromethane in Ar or N2 atmosphere.

We investigate atomic and molecular emission of laser-ablated nitromethane in an Ar or N2 buffer gas, with fs laser-induced breakdown spectroscopy. The electronic bands of CN, C2, and NH molecules and the atomic transition lines of C I, N I, and Hα are identified. The time series of the emissions are obtained, and the formation mechanisms of CN and C2 are deduced. The CN violet system, the B2Σ+-X2Σ+ (0-0) band, is chosen to extract plasma temperature from the experimental spectra.