Line Selection and Parameter Optimization for Trace Analysis of Uranium in Glass Matrices by Laser-Induced Breakdown Spectroscopy (LIBS)

Abstract

Laser-induced breakdown spectroscopy (LIBS) has been evaluated for the determination of uranium in real-world samples such as uraninite. NIST Standard Reference Materials were used to evaluate the spectral interferences on detection of uranium. The study addresses the detection limit of LIBS for several uranium lines and their relationship to non-uranium lines, with emphasis on spectral interferences. The data are discussed in the context of optimizing the choice of emission lines for both qualitative and quantitative analyses from a complex spectrum of uranium in the presence of other elements. Temporally resolved spectral emission intensities, line width, and line shifts were characterized to demonstrate the parameter influence on these measurements. The measured uranium line width demonstrates that LIBS acquired with moderately high spectral resolution (e.g., by a 1.25 m spectrometer with a 2400 grooves/mm grating) can be utilized for isotope shift measurements in air at atmospheric pressure with single to tens of parts per million (ppm) level detection limits, as long as an appropriate transition is chosen for analysis.

Characteristics of the ablation plume induced on glasses for analysis purposes with laser-induced breakdown spectroscopy

“…Since last ten years, laser-induced breakdown spectroscopy (LIBS) has been demonstrated as an efficient tool for elemental analysis in transparent or translucent dielectric materials, glasses or crystals, for applications required in many fields such as archeological research [1][2][3], forensic investigation [4][5][6], nuclear waste storage [7][8][9], or gemstone identification and qualification [10][11][12]. In the fundamental point of view, laser ablation of transparent or translucent dielectric materials corresponds to specific processes which are distinguished from what happens in laser ablation of metals.…”

Persistence of uranium emission in laser-produced plasmas

“…Trace concentrations of U have been detected, with detection limits determined to be in the parts per million (ppm) range. [10][11][12] Various ambient environments have also been explored for detection of bulk SNMs, including air and Ar at various pressures. 13 As U has a very complex atomic structure with closely packed emission lines, high spectral resolution is a crucial figure of merit.…”

Spatio-temporal evolution of uranium emission in laser-produced plasmas

“…Typically all emission lines show a maximum width closer to the target as well as at early times where the Stark effect is predominant. Recently Choi et al [8] evaluated the FWHM of U I and U II transitions with time and found that adequate isotopic separation is possible at later times to determine isotopic ratios. Their time…”

“…LA-Laser Absorption Spectroscopy (LA-LAS) is an extremely sensitive method capable of probing elemental as well as isotopic ground and excited state populations [4,5]. LA -Optical Emission Spectroscopy (LA-OES), commonly called Laser Induced Plasma Spectroscopy (LIPS) or Laser Induced Breakdown Spectroscopy (LIBS), provides another dimension to LA-hyphenated techniques in nuclear forensics where light emission from the plasma plume is analyzed [6][7][8][9][10][11][12][13][14].…”

“…emit crowded spectral features immersed in strong continuum emission (due to free-free and free-bound transitions) [8]. Thus there is a need to characterize and optimize the signal to background (S/B) ratios of elemental lines to improve the analytical merits.…”