Rapid isotopic analysis using heterodyne laser induced breakdown spectroscopy

Isotopic analysis of suspect materials is an effective tool for identifying and characterizing nuclear. Isotope ratios of uranium, plutonium, lithium, and hydrogen are particularly informative for distinguishing fuel for nuclear power plants from weapons-grade material. Existing instrumentation capable of measuring isotope ratios to high precision and accuracy is expensive, bulky, and requires time-consuming sample preparation. Ideal replacements would not only allow rapid measurements, but would be compact and portable for field work. Mesa Photonics proposes an improvement to laser induced breakdown spectroscopy (LIBS) that achieves the high spectral resolution needed for isotope ratio determinations in a small, lightweight, package that can be added easily to existing LIBS instruments. This approach takes advantage of LIBS strengths simple, fast sample preparation and analysis, able to work with samples at atmospheric pressure, and operation without consumable supplies while solving known LIBS problems that include poor spectral resolution, calibration problems due to matrix effects, and limited dynamic range. In Phase I, the proposed technique will be tested by measuring 85Rb/87Rb isotope ratios in natural abundance rubidium carbonate and in mixtures of the isotopically pure (99+%) carbonates. LIBS results will be tested against isotope analysis by a commercial laboratory using laser ablation, inductively coupled plasma, mass spectrometry (LA-ICP-MS). Rubidium was chosen for Phase I because the isotopic splitting is only 10 pm at 780 nm and requires better capabilities than are needed for determining isotope ratios of uranium, plutonium, lithium, or hydrogen. Commercial Applications and Other Benefits: Commercial analyzers will be person-portable devices costing $60,000 to $90,000 depending on laser power and number of simultaneous isotope ratio measurements that will have capabilities comparable to LA-ICP-MS instruments costing between $200,000 and $400,000. The primary market niche is field measurements for nuclear forensics. Additional markets include elemental and isotopic analysis for geochemistry.