Fluorescence imaging of ion distributions in an inductively coupled plasma with laser ablation sample introduction

Abstract

a b s t r a c tHigh-resolution images of the spatial distributions of Sc II, Ca II, and Ba II ion densities in the 10 mm upstream from the sampling cone in a laser ablation-inductively coupled plasma-mass spectrometer (LA-ICP-MS) were obtained using planar laser induced fluorescence. Images were obtained for each analyte as a function of the carrier gas flow rate with laser ablation (LA) sample introduction and compared to images with solution nebulization (SN) over the same range of flow rates. Additionally, images were obtained using LA at varying fluences and with varying amounts of helium added to a constant flow of argon gas. Ion profiles in SN images followed a pattern consistent with previous work: increasing gas flow caused a downstream shift in the ion profiles. When compared to SN, LA led to ion profiles that were much narrower radially and reached a maximum near the sampling cone at higher flow rates. Increasing the fluence led to ions formed in the ICP over greater axial and radial distances. The addition of He to the carrier gas prior to the ablation cell led to an upstream shift in the position of ionization and lower overall fluorescence intensities.

Evaluation of particle size distributions produced during ultra-violet nanosecond laser ablation and their relative contributions to ion densities in the inductively coupled plasma

“…A detailed review of the instrumentation used for these experiments was presented in ref. [12]. A brief overview, including modifications, will be provided here.…”

“…The fluorescence schemes can be found in ref. [12]. The fluorescence was captured on a gated, iCCD (7361-0001, Princeton Instruments, Trenton, NJ).…”

“…In a recent paper, high resolution images obtained using LIF were used to investigate the influence of laser fluence, carrier gas, and the presence of water on various ion distributions in the ICP in LA-ICPMS [12]. Significant contributions to the observed changes in images reported in that paper were suspected to be related to particle size effects.…”

The effects of He on ablation and inductively coupled plasma environment in ultra-violet, nanosecond laser ablation inductively coupled plasma mass spectrometry

“…Although our experiments reported in reference [2], in combination with reports from other groups cited above, suggested that changes in measured ion densities that accompanied the addition of helium to the ablation gas were due to changes in the plasma, the evidence was indirect. Caution is needed in drawing conclusions based on interlaboratory comparisons because of inevitable differences in equipment and procedures.…”

“…In a recent paper, we investigated the effectson ion distributions in the ICP of adding helium to argon gas upstream from the ablation cell using laser induced fluorescence (LIF) [2]. We were surprised to find that helium added to the carrier gas led to a decrease in the overall ion densities within the ICP.…”