Laser ablation molecular isotopic spectrometry of carbon isotopes

Abstract

Quantitative determination of carbon isotopes using Laser Ablation Molecular Isotopic Spectrometry (LAMIS) is described. Optical emission of diatomic molecules CN and C 2 is used in these measurements. Two quantification approaches are presented: empirical calibration of spectra using a set of reference standards and numerical fitting of a simulated spectrum to the experimental one. Formation mechanisms of C 2 and CN in laser ablation plasma are briefly reviewed to provide insights for implementation of LAMIS measurements. A simulated spectrum of the 12 C 2 Swan system was synthesized using four constituents within 473.5-476.5 nm.Simulation included three branches of 12 C 2 (1-0), branches R(0-0) and R(1-1), and branch P(9-8) of 12 C 2 . Spectral positions of the tail lines in R(0-0) and R(1-1) were experimentally measured, since they were not accurately known before. The Swan band (1-0) of the isotopologue 13 C 12 C was also simulated. Fitting to the experimental spectrum yielded the ratio 13 C/ 12 C = 1.08% in a © 2015. This manuscript version is made available under the Elsevier user license http://www.elsevier.com/open-access/userlicense/1.0/ good agreement with measurements by isotope ratio mass spectrometry. LAMIS promises to be useful in coal, oil and shale exploration, carbon sequestration monitoring, and agronomy studies.

Combination of atomic lines and molecular bands for uranium optical isotopic analysis in laser induced plasma spectrometry

“…Consequently, isotopic shifts exhibited in molecular spectra may exceed those in atomic spectra by two to three orders of magnitude [1][2][3], and become readily measurable in an atmosphericpressure plasma. Isotopic LAMIS signatures from a number of elements, including H, B, C, N, O, Sr and Zr [1][2][3][4][5][6], have already been reported.…”

“…Several researchers have reported hydrogen-deuterium analysis by means of LIBS operated under atmospheric pressure [4,[13][14][15][16]. Cremers et al [13] also performed isotopic analysis on 6 Li and 7 Li with LIBS under atmospheric pressure. For heavy elements, uranium has been mostly studied [13,14,17,18].…”

Reduction of spectral interferences and noise effects in laser ablation molecular isotopic spectrometry with partial least square regression – a computer simulation study

“…is an appropriate choice for isotopic analysis of 13 C because the line positions from the 13 C 12 C isotopologue is red shifted from the more abundant 12 C 12 C. As the bandheads of the C 2 d 3 Π ga 3 Π u system degrade to blue, the red-shifted 13 C 12 C (1-0) bandhead appears in front of and not buried inside the decaying part of the dominant 12 C 2 bandhead. However, other rovibronic structures from the Swan band, in particular those from 0-0, 1-1 and 9-8 [21], of the dominant 11 12 C 2 isotopologue emit in close wavelength proximity to the bandhead of 13…”

“…The C 2 Swan band (d 3 Π ga 3 Π u ) with  = +1 was selected as the representative system, as the natural abundance of 13 C is about 1.1%. Further, the C 2 Swan band is one of the strongest molecular bands present when an organic material is ablated [17,18], and therefore, has been utilized for isotopic analysis of carbon [19][20][21]. Although the spectra of both the standards and the samples are synthetic in nature, their characteristics (e.g., noise amplitude and distribution, signal strength, and signal-tobackground ratio) were all experimentally characterized.…”

Standoff Detection of Uranium and its Isotopes by Femtosecond Filament Laser Ablation Molecular Isotopic Spectrometry

“…These limitations are not always compatible with remote measurements. In the recently developed technique of Laser Ablation Molecular Isotopic Spectrometry (LAMIS)212223, radiative molecular transitions from diatomic molecules are used to extract the isotopic composition of a sample under ambient atmospheric conditions. A similar method has been demonstrated in earlier work by Niki et al 24,.…”