Characterization of a pulsed glow discharge laser ablation system using optical emission

Investigations involving laser-based sampling of copper into an auxiliary p ulsed glow discharge for ionization and excitation are presented. The inter action of the ablated copper with the auxiliary glow discharge was studied by monitoring the copper atom emission signal at 368.744 nm. Results demons trate the ability to time ablation appropriately to access specific tempora l regions of the pulsed plasma. More specifically, laser-ablated material w as introduced into the glow discharge negative glow during the afterpeak, I onization and excitation was accomplished by collisions with a metastable a rgon population produced by the glow discharge (Penning ionization) followe d by recombination to yield excited-state Cu atoms, The work presented inve stigates parameters that affect the atomic emission signal intensity of the ablated material, including cathode-to-target distance, discharge gas pres sure, and relative timing of discharge and ablation, Results demonstrate th at decreasing the glow discharge working gas pressure increases the transpo rt efficiency of laser-ablated material into the negative glow. These inves tigations are part of an ongoing series of studies on sample introduction s chemes that utilize different ionization and excitation mechanisms found in pulsed glow discharge plasmas.