V-shape plasma generated by excimer laser ablation of graphite in argon: Spectroscopic investigations

Continuing previous works on the dynamics of carbon plasmas generated by excimer laser ablation in vacuum, we report here a new study using Ar as background gas. The increased collision rate allows extended (both spatially and temporally) investigations of the low-emitting axial region of the unusual V-shape transient plasma evidenced in our previous works. The systematic study performed here by fast-gate intensified CCD photography and space- and time-resolved optical emission spectroscopy led to an extensive database, especially on the evolution of C, Ar and C-dimer (monitored through the Swan bands). The enhancement of the dimer formation (which has an important role in carbon plasma chemistry) in the lateral structures is confirmed and even amplified by the use of background gas. Furthermore, temperature and electron density values have been estimated from the spectroscopic data, providing additional proofs for the validity of the plasma dynamics scenario built for this unusual plume shape.