Species-resolved imaging and gated photon counting spectroscopy of laser ablation plume dynamics during KrF- and ArF-laser PLD of amorphous diamond films

Gated photon counting spectroscopy and species-resolved ICCD photography have been applied to study the weak plasma luminescence which occurs following the propagation of the initial ablation plume in vacuum and during the 'rebound' of the plume with a substrate during pulsed laser deposition from ArF- and KrF-laser of amorphous diamond. Three principal regions of plume emission have been characterized: (1) a bright luminescent ball (v approx.3-5 cm/μs) displaying nearly entirely C⁺ emission which appears to result from laser interaction with the initial ejecta, (2) a spherical ball of emission (v approx.1 cm/μs) displaying neutral carbon atomic emission lines and, at early times, jets of excited C₂, and (3) a well-defined region of broadband emission (v approx. 0.3 cm/μs) near the target surface first containing emission bands from C₂, then weak, continuum emission thought to result from C₃ and higher clusters and/or blackbody emission from hot clusters or nanoparticles. For both lasers, the measurements reveal an explosive interaction within the plume which results in a variety of new gas dynamic observations in vacuum.