en.Wedoany.com Reported - A research team at the Institute of Experimental Physics at Graz University of Technology (TU Graz) has developed a new ultraviolet dual-comb spectrometer capable of detecting gaseous air pollutants with extremely high precision and sensitivity. The device uses dual ultraviolet laser beams to measure the concentration of harmful gases such as formaldehyde within half a second, with a measurement range of up to 2.5 kilometers. It is suitable for mobile measurement of air pollutants and gas leaks in urban, industrial, and agricultural areas.
The spectrometer works by generating two laser pulses in the ultraviolet spectral range within a fraction of a second. When these pulses irradiate gas molecules, they excite electrons and induce rotational-vibrational transitions. Each gaseous substance has unique rotational-vibrational transitions, absorbing part of the laser light in a distinctive manner, forming its own "fingerprint." Birgitta Schultze-Bernhardt, head of the research team, stated that the ultraviolet dual-comb spectrometer can identify these characteristics.
About two years ago, Schultze-Bernhardt and her team developed the first version of the spectrometer, which was the world's first device of its kind at the time, but measurements required a large laboratory setup. The new version has been downsized to the size of a moving box, thanks to the use of a single laser source to generate dual laser pulses and the elimination of complex electronic stabilization processes for the system.
The spectrometer can detect ultraviolet light frequencies with a resolution of 1 GHz, outperforming traditional ultraviolet spectrometers. In tests with formaldehyde, researchers made new discoveries about the ultraviolet light absorption of this air pollutant, measuring absorption patterns that had previously gone unobserved due to insufficient device resolution.
Using measurement data from TU Graz, errors were found in the rotational constants of formaldehyde that had been preserved in physics databases and textbooks since the 1960s. Schultze-Bernhardt explained that in collaboration with the Atomic and Molecular Physics Division of the Harvard-Smithsonian Center for Astrophysics in the United States, the team corrected the values of this molecular property parameter by up to 15%. This progress in basic research also benefited from cooperation with Rolf Breinbauer at the Institute of Organic Chemistry at TU Graz (Institut für Organische Chemie, TU Graz), who prepared high-purity formaldehyde for the study using a two-step process.
Beyond basic research, the spectrometer has the potential to make air pollutant and gas leak measurements in urban and industrial areas more precise and convenient. Schultze-Bernhardt noted that the device can, in principle, accurately detect any semi-transparent gaseous substance, and the team is working on determining the concentrations of multiple pollutants in a single measurement. Under a Proof of Concept Grant from the European Research Council (ERC), she is developing an ultraviolet spectrometer that can be used for air quality monitoring by non-specialists, such as companies or environmental agencies.
The development of the ultraviolet dual-comb spectrometer is based on a research project led by Schultze-Bernhardt, funded by the Austrian Science Fund (FWF) and the European Research Council (ERC). The Graz Cooperation Initiative (NAWI Graz) provided funding for the new laser source of the current spectrometer under the infrastructure funding framework.
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