Estimation of Transition Probabilities by Laser-Induced Breakdown Spectroscopy for the Expanded Application of Calibration Free Methods

Laser-Induced Breakdown Spectroscopy (LIBS) is a versatile technique for compositional analysis for solids, liquids, and gases. LIBS is an asset for the quantitative or qualitative analysis of resource limited materials like actinides and rare earths because it is quasi-nondestructive: typically, only a few nanograms of material are ablated into a plasma for optical emissions. Calibration Free – LIBS (CF-LIBS) is of interest being applied to rare earths; however, it is currently lacking fundamental data needed for application. This fundamental data is transition probabilities, and they allow LIBS to be employed without having to make and use matrix matched standards for a calibration curve. Two studies were employed in this work which aim to utilize the unique qualities of LIBS to prepare a way for transition probabilities to be estimated for resource limited material. Eu pellets were made for the first study and used as a test and validation set. The second study used small amounts of solutions containing a lanthanide and Sr, which acted as an internal reference, dried on Al pellets. In the studies discussed herein, Saha-Boltzmann plots were used to estimate the temperature and electron density of the plasmas generated. This information was then used to calculate previously unknown transition probabilities. Results in the second study showed uncertainties lower than 10% in some cases, while the first study only got down to 35%. In the first study, 8 previously unreported transitions probabilities are reported, and 967 transitions probabilities are reported for the second study. Self-absorption corrections were used in the second study, along with an increase of sampled data which catered to decreasing the uncertainty in the estimations. By calculating new transition probabilities with the methods presented in this thesis, it is possible to complete these estimations with high accuracy and low resource cost, which suggest it is a viable method to use for resource restricted elements like actinides. CF-LIBS is of interest for the actinides because of its many benefits including in-situ, fast, quasi-nondestructive, remote viewing, and unrequired dilution of samples.