A new photoacoustic technique, which measures the sound generated when light interacts with molecules, enables the detection of gases, such as atmospheric pollutants, present in extremely small quantities at parts-per-quadrillion level that are otherwise difficult or otherwise impossible to detect.

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A new photoacoustic technique, which measures the sound generated when light interacts with molecules, enables the detection of gases, such as atmospheric pollutants, present in extremely small quantities at parts-per-quadrillion level that are otherwise difficult or otherwise impossible to detect.