There, a light beam emitted from a quantum cascade laser at 4.5 microns - an ideal wavelength for sensitive gas detection - interacts with the carbon dioxide inside a 1-meter-long optical cavity with highly reflective mirrors on each end.As the light repeatedly bounces between the mirrors, the radiocarbon molecules in the cavity absorb some of the light. De Natale, "Spectroscopic detection of radiocarbon dioxide at parts-per-quadrillion sensitivity" Optica, 3, 4, 385 (2016). Even if the absorption is small for a single pass, thousands of passes provide enough absorption to detect even trace amounts of radiocarbon.
SCAR offers significant time and cost savings compared to the standard approach for carbon dating and could be useful for a host of other applications such as measuring emissions from fossil fuels or certifying the amount of biogenic content in biofuels.Faster, cheaper carbon dating Current carbon dating processes require researchers to send a sample to a large facility with an accelerator mass spectrometer and then wait several weeks to get results back.A device such as this could offer a way to tie a monetary cost, or tax, to pollution."We developed a very general spectroscopic technique and showed that it can be used to detect radiocarbon dioxide," said Giovanni Giusfredi, a member of the research team.Accelerator mass spectrometry measures the amount of carbon-14, or radiocarbon, present in a sample, which can be used to calculate its age.
Around the world, only about 100 facilities house this equipment."Our group collaborated with other research groups in the U. S., Japan and Switzerland for the theoretical analysis and to study quantum cascade lasers." The researchers are continuing to refine their instrument and explore new applications. Over time, carbon-14 decays radioactively and turns into nitrogen.A living organism takes in both carbon-12 and carbon-14 from the environment in the same relative proportion that they existed naturally.The new technique can deliver results in just two hours, with each test costing about half what it would if conducted using an accelerator mass spectrometer.