We demonstrate highly efficient cavity ringdown spectroscopy in which a broad-bandwidth optical frequency comb is coherently coupled to a high-finesse optical cavity that acts as the sample chamber. 125,000 optical comb components, each coupled into a specific longitudinal cavity mode, undergo ringdown decays when the cavity input is shut off. Sensitive intracavity absorption information is simultaneously available across 100 nanometers in the visible and near-infrared spectral regions. Real-time, quantitative measurements were made of the trace presence, the transition strengths and linewidths, and the population redistributions due to collisions and the temperature changes for molecules such as C2H2, O2, H2O, and NH3.
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http://dx.doi.org/10.1126/science.1123921 | DOI Listing |
Appl Spectrosc
January 2025
Department of Earth Sciences, Geological Institute, , ETH Zurich, Zurich, Switzerland.
Cavity ring-down spectroscopy (CRDS) is rapidly becoming an invaluable tool to measure hydrogen (δ²H) and oxygen (δO) isotopic compositions in water, yet the long-term accuracy and precision of this technique remain relatively underreported. Here, we critically evaluate one-year performance of CRDS δ²H and δO measurements at ETH Zurich, focusing on high throughput (~200 samples per week) while maintaining required precision and accuracy for diverse scientific investigations. We detail a comprehensive methodological and calibration strategy to optimize CRDS reliability for continuous, high-throughput analysis using Picarro's "Express" mode, an area not extensively explored previously.
View Article and Find Full Text PDFACS Earth Space Chem
December 2024
School of Chemistry, The University of Edinburgh, Joseph Black Building, David Brewster Road, King's Buildings, Edinburgh EH9 3FJ, Scotland, U.K.
Identification of the molecular carriers of diffuse interstellar bands (DIBs) requires gas phase electronic spectra of suitable candidate structures. Recording the spectra of these in the laboratory is challenging because they include large, carbon-rich molecules, many of which are likely to be ionic. The electronic spectra of ions are often obtained using action spectroscopy methods, which can induce small perturbations to the absorption characteristics and hinder comparison with astronomical observations.
View Article and Find Full Text PDFACS Omega
December 2024
VTT Technical Research Centre of Finland Ltd, P.O. Box 1000, Espoo, FI-02044, VTT, Finland.
Radiocarbon analysis of nuclear waste produced in nuclear facilities lacks fast, in situ detection methods. Moreover, the amount of radiocarbon desorbing from graphitic waste is not well known. In this study, we demonstrate the use of mid-infrared cavity ring-down spectroscopy combined with an automatic sample processing unit as a method to examine radiocarbon concentration in three types of nuclear waste: spent ion-exchange resin, graphite, and graphite outgassing in sealed storage crates.
View Article and Find Full Text PDFACS Earth Space Chem
November 2024
Department of Chemistry, University of Oxford, Oxford OX1 3QZ, U.K.
The radiative forcing caused by atmospheric aerosol represents one of the largest uncertainties in climate models. In part, these uncertainties derive from poor characterizations of the optical properties of light-absorbing brown carbon (BrC) containing aerosols. Here, single particle cavity ring-down spectroscopy (SP-CRDS) is used to determine the complex refractive index at the optical wavelength of 405 nm for aqueous particles composed of an abundant BrC species, 4-nitrocatechol.
View Article and Find Full Text PDFIn a wide range of laser applications, the optical losses of optical materials used in the laser systems are closely linked to the laser-induced damage and laser beam quality deterioration. It is demonstrated in this paper that when the pulsed cavity ring-down (CRD) technique is employed to measure the optical loss of uncoated substrates inserted in the ring-down cavity with normal incidence, the surface reflection of the uncoated substrate causes a significant overestimation of the optical loss. The degree of overestimation increases rapidly with the increasing surface reflectance.
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