Mol density measurements by laser induced fluorescence spectroscopy

The density of molybdenum atoms produced by sputtering of a TZM (molybdenum) target by Ar+ ions is measured by laser induced fluorescence (LIF) using tunable dye laser. The excitation transition involved is a(7)S(3)-z(5)P(3)(0) at 345.64 nm, while the fluorescence signal is from the decay z(5)P(3)(0)-a(5)S(2) at 550.6 nm. The LIF measurements are carried out by varying the laser power incident on Mo atoms by means of neutral density filters. An absolute calibration of the detection system together with the realization of a well defined optical probe volume allows for the determination of the density of the emitting atoms. An evaluation of LIF diagnostic performance on Frascati Tokamak upgrade put a lower limit of 2.5X10(14) atoms/m(3) on the detectable local density of MoI close to the toroidal limiter. (C) 1999 American Institute of Physics. [S0034-6748(99)66001-4].