Mercury ion measurement in an inductively coupled discharge lamp

Summary form only given, as follows. Laser induced fluorescence technique is used to detect the presence of Hg/sup +/ in a 2.5 MHz Hg-Kr (0.5 Torr) inductively coupled discharge. The discharge is created within a cylindrical quartz container with a coaxial inner wall (76 mm OD, 23 mm ID and 103 mm length). RF power is transferred to the discharge via a Ferrite core (/spl mu/=14) centrally located within the inner tube. The discharge power is fixed at 20 W. The pump laser beam is directed axially through the discharge and the LIF signal detected perpendicular to the pump beam. The detected LIF at 281.5 mm is generated by a two photon process with the pump beam at 563.0 nm. The pump beam is generated by a tuneable dye laser (PDL-2) pumped is pumped by a Nd:YAG Laser (Spectra Physics GCR-150). The Hg/sup +/ ions are essentially pumped from the ground state to the nearest excited state which is the 5d/sup 9/6s/sup 2/ /sup 2/D/sub 5/2/ level which has a radiative lifetime of 86 ms. Due to neutrality conditions in the plasma, the Hg/sup +/ ion density are thus a measure of the electron density as well.