Scientists have discovered a way to detect trace amounts of chemicals in the air by using an IR laser to identify the unique frequency of individual molecules. The technique is sensitive enough to detect a molecule present in the air at concentrations as low as one part per billion. This technique could be used to scan the atmosphere for toxic agents in order to alert communities to a biological or chemical attack. University of Central Florida (UCF) optics and photonics professor Konstantin Vodopyanov and his team have found a way to use IR lasers to detect even trace amounts of chemicals in the air. Every chemical is made up of individual molecules that vibrate at their own unique frequency. Vodopyanov has found a way to use lasers to detect these vibrations. Courtesy of UCF: Karen Norum. Developed by a team at the University of Central Florida (UCF), the technique uses spectroscopy with broadband MIR frequency combs to sense trace molecules. According to researchers, it can provide fast, simultaneous acquisition of 350,000 spectral data points, spaced by a 115-MHz intermodal interval over the 3.1- to 5.5-µm spectral range. The team demonstrated parallel detection of 22 trace molecular species in a gas mixture, including isotopologues containing isotopes such as 13C, 18O, 17O, 15N, 34S, 33S, and deuterium, with part-per-billion sensitivity and sub-Doppler resolution. The technique features absolute optical frequency referencing to an atomic clock and exhibits a high degree of mutual coherence between the two MIR combs. Researchers compare their technique to an approach that is used in the medical field to detect biomarkers for different kinds of health conditions by taking breath samples. “The frequencies of molecules are very distinct, but they are invariant,” said professor Konstantin Vodopyanov. “Think of it as a molecular fingerprint. So when we use the laser we can detect these fingerprints with great precision.” The UCF team’s approach could facilitate the development of sensors for detecting airborne agents encountered in a biological or chemical attack, or for uncovering indications of life on other planets. “We are now working on broadening the range of the laser frequencies that can get the job done. If costs can be reduced and the tech made mobile, the applications could be endless,” Vodopyanov said. The research was published in Nature Photonics (doi:10.1038/s41566-018-0135-2). University of Central Florida (UCF) professor Konstantin Vodopyanov and his team have found a way to use IR lasers to detect potentially dangerous chemicals in the air. Courtesy of UCF.