Emission studies of the plume produced by KrF laser ablation of Fe in ambient nitrogen gas

Time-resolved emission measurements for an expanding plume during laser ablation of Fe in nitrogen gas are performed. Most emissions are identified as being due to Fe neutrals and are divided into two groups with different time-of-flight distribution, which are fitted with shifted Maxwellian distribution. The most probable velocities are estimated to be 2×10⁴ m/s and 1×10⁴ m/s. Because of the apparent time lag between the emission of N₂⁺ and that of an Fe neutral, it is considered that N₂⁺ does not contribute to the nitridation of deposited thin film.