Laser spectroscopy: A potential versatile solution for radiocarbon analyses

Radiocarbon ( 14 C) measurements play important roles in dating and tracing applications where the isotopic concentration can differ from 0.1 to 10 6 pMC (percent modern carbon). A liquid scintillation counter cannot provide enough sensitivity when dealing with low-concentration samples of limited amounts over a reasonable time period. Accelerator mass spectroscopy (AMS) measures low-concentrations well but must first do dilution for high-concentration samples, and suffers from high instrument and maintenance costs. S aturated absorption CA vity R ing-down spectroscopy (SCAR) has now been developed into a practical technique with performances close to AMS but at much lower costs. The dynamic range covers 1–10 5 pMC, and the measurement uncertainties in the range of 0.4–1 pMC can be achieved within 0.5–2.5 hr of operation time. SCAR measures CO 2 gases directly without graphitization in sample preparation. The typical sample consumption is ∼1 mg of carbon mass and the time for sample preparation can be as short as 15 min. Applications of SCAR to Suess-effect evaluation, biogenic-component analysis, ancient- and modern-sample dating, food-fraud detection and medicine-metabolism study have all been demonstrated by employing a close-to-automatic sample preparation system.