Radiocarbon dioxide detection based on cavity ring-down spectroscopy and a quantum cascade laser

Abstract

Monitoring of radiocarbon (C14) in carbon dioxide is demonstrated using mid-infrared spectroscopy and a quantum cascade laser. The measurement is based on cavity ring-down spectroscopy, and a high sensitivity is achieved with a simple setup. The instrument was tested using a standardized sample containing elevated levels of radiocarbon. Radiocarbon dioxide could be detected from samples with an isotopic ratio C14/C as low as 50 parts-per-trillion, corresponding to an activity of 5 kBq/m(3) in pure CO(2), or 2 Bq/m(3) in air after extraction of the CO(2) from an air sample. The instrument is simple, compact, and robust, making it the ideal tool for on-site measurements. It is aimed for monitoring radioactive gaseous emissions in a nuclear power environment, during the operation and decommissioning of nuclear power plants. Its high sensitivity also makes it the ideal tool for the detection of leaks in radioactive waste repositories.

Room temperature line lists for CO2 symmetric isotopologues with ab initio computed intensities

“…As was shown in our previous papers considering the main 12 C 16 O 2 isotopologue (denoted here as 626), a fully ab initio dipole moment surface is capable of providing such a level of accuracy [2,3]. The next step is to address other isotopologues, which are ubiquitous in natural samples and may interfere with spectral lines of the main isotopologue as well as other species [4,5,6,7].…”

Ultra-sensitive cavity ring-down spectroscopy in the mid-infrared spectral region

“…The relatively low cost instrument described herein is well suited for precise measurements of ultra-trace gas species including radiocarbon [20, 21] and atmospherically relevant free radicals. This instrument has been used to measure birefringence in supermirror coatings [14] and may be applied in addressing other challenges in fundamental physics including the search for symmetrization postulate violations in molecular physics [22] and measurements of absolute number densities for magnetically-trapped ultra-cold molecules using absorption-based techniques [23].…”

Advances in Mid-Infrared Spectroscopy for Chemical Analysis

“…Recent advances in cavity ring-down spectroscopy are aiming at optically more robust and compact instruments that enable mobile or on-site applications. Using a continuous-wave QCL setup with an overall footprint of approximately 90 × 60 cm, Genoud et al (113) demonstrated radio carbon trace gas detection with a detection limit of 14 for both high spatial and temporal resolution. For the detection of reaction processes and mechanisms, for example, the role of methanol in catalytic reactions such as CO 2 hydrogenation or CH 4 oxidation, information on particularly fast changes of local concentration conditions are of considerable interest for efficiently monitoring the overall conversion reaction.…”