Spatial Distribution of Vacuum Ultraviolet Radiation in an Inductively Coupled Plasma

Spatially resolved emission maps of an ICP as a function of torch design, power, and gas flow rate have been obtained for O, N, Cl, Br, and C in the vacuum ultraviolet with the use of an Abel inversion data reduction algorithm. Two coolant tube configurations were studied, one a standard strait coolant tube with a “bell”-style collar, and a second with a “T”-shaped sidearm tube. The studies show that the maximum emission intensities for Br and Cl occurred below the top of the coolant tube and that the N 149.28-nm emission cannot be observed for the bell collar configuration. The investigation of the T-tube configuration yielded useful information for all elements studied, with optimum observation heights ranging from 8 mm above the load coil for C at 165.70 nm to 20 mm above the load coil for O at 130.49 nm. In most cases, the maximum intensity is observed in the center of the discharge. Signal-to-noise studies indicate that the highest power practical with the minimum flow rate possible should be used for the analysis of the four nonmetals investigated.