LIBS-MLIF of REE for Isotopic Analysis

Michael Gaft, Department of Physics, Ariel University, Ariel, Israel (michaelga@ariel.ac.il)
Lev Nagli, Department Of Physics, Ariel University, Ariel, Israel
Yosef Raichlin, Department Of Physics, Ariel University, Ariel, Israel
Andrey Gorychev, Department Of Physics, Ariel University, Ariel, Israel

Isotope ratio measurements from molecular spectra are advantageous for light elements. For heavy elements, the molecular isotopic effect is smaller because it scales with the reduced mass. The lightest REE from Sc to Pr exist in nature as one or mostly one stable isotope. The spectra of the next ones from Nd to Eu are without sharp spectral features and not perspective for isotopic analysis. Gadolinium has several isotopes with significant abundances, the spectra have rich vibrational and rotational structures in blue region, the electronic energy levels are well interpreted and LIBS-MLIF [1] spectra demonstrate new features not detected in LAMIS [2] and perspective for isotopic shift analysis.

Molecular isotope splitting increases as the quantum numbers υ and Δυ increase. Transitions with Δυ= 0, ± 1,  ± 2, ... are all allowed, but the intensity become weaker as Δυ increases. LIBS-MLIF techniques enables bigger isotopic shift by using vibronic transitions with larger Δυ [3]. In case of Gd, 3-1 vibrational transition is characterized by relatively strong emission intensity and has theoretical isotopic shift of 1.2 cm^-1. Small spectral changes compared with natural Gd spectrum are repeatedly detected in monoisotopic ¹⁵⁸Gd but it must be proved with higher spectral resolution (presently 0.02 nm).

Rotational structure also can be used for isotopic detection but usually it may not be done because of weak intensity and pure resolution. LIBS-MLIF enables to receive well-developed rotational structure which may be used for isotopic shift analysis.

REFERENCES

[1] L. Nagli, M. Gaft. Appl. Spectr. 70(2016)1-8.

[2] R. E. Russo, A. Bol’shakov, X. Mao, C. McKay, D.Perry, O. Sorkhabi. Spectrochim. Acta B, 66(2011)99-104.

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Short Biography of Presenting Author

I received high education in physics of solids from Moscow Steel and Alloys Institute, USSR, in 1975 and PhD in physics of minerals from the All-Union Institute of Mineral Resources of Moscow in 1979. Between 1975 and 1990, I was a researcher in the All-Union Institute of Mineral Resources of Moscow. I immigrated to Israel at August 1990. Between 1990 and 2001, I was a Physics lecturer in The Open University of Israel. Between 2001 and 2005, I was a Senior Scientist in International Technologies Lasers, Israel. Between 2005 and 2016, I was a Chief Scientist in Laser Detect Systems, Israel and a R&D Director in the Laser Distance Spectrometry, Israel. Since October 2016, I am Physics Lecture in Department of Physics, Ariel University, Israel.