Fig. 1. ²³³U, ²³⁵U and ²³⁸U emission spectra in the 424.37~424.45 nm wavelength regions for the certified isotopic reference material IRMM-199 containing ~0.45 mg·kg^-1 each of ²³³U, ²³⁵U, and ²³⁸U as well as a conventional U single-element standard solution (²³⁸U and ²³⁴U) are also additionally displayed. ²³³U (424.398 nm), ²³⁵U (424.412 nm) and ²³⁸U (424.437 nm) can be clearly distinguished, and ²³⁴U can also be effectively identified^[11]

Fig. 2. Emission spectra of (a) atomic carbon emission line, (b) molecular isotopic band during LAMIS of carbon isotope sample
Spectrometer resolution, gate delay and width were 0.02 nm, 4 μs and 2 μs, respectively^[25]

Fig. 3. LA-TDLAS spectra (⁶Li and ⁷Li) at delay time of 340 μs after ablation pulse^[43]

Fig. 4. Z-AAS determination of (a) ¹⁹⁸Hg, ²⁰⁰Hg, ²⁰¹Hg, and ²⁰²Hg isotopes (symbols) and the simulation results (solid lines) and (b) mixed isotopes of ²⁰⁰Hg and ¹⁹⁸Hg and the natural Hg^[8]

Fig. 5. Absorption of ¹⁴N and ¹⁵N-isotopes of N₂O centered at ~2 188.688, ~2 188.756 and ~2 188.938 cm^-1, respectively
The measured data (green points) and fitted curves (red lines) are shown in the upper trace and the residuals (blue lines) in the lower trace^[52]

Fig. 6. Spectra of AlCl (1:1, ³⁵Cl/³⁷Cl molar ratio solution) at wavelengths of: (a) 261.418 nm; (b) 261.695 nm; (c) 261.819 nm; (d) 262.238 nm; (e) 262.697 nm; (f) 263.216 nm; (g) 263.807 nm; and (h) 264.490 nm
They were obtained for 400 ng of Cl, 10 mg of Al and 20 mg of Pd. However, B shows two spectraof AlCl with different isotope abundance: in black, the one obtained for 400 ng of Cl of CRM NIST 975a (³⁵Cl, 75.774%), and in red, the one obtained for 400 ng of Cl of CRM AE642 (³⁷Cl, 98.122%)^[53]

Table 1. Isotope analysis methods for optical emission spectroscopy

Table 2. Isotope analysis methods by LAMIS