Femtosecond laser ionization and fragmentation of molecules for environmental sensing

Recent studies have demonstrated that femtosecond laser pulses have high potential in application to environmental science. Because of the properties of ultrafast, broadband and high power, the propagation of femtosecond laser pulses in air can lead to the generation of a strong field of 1013–1014 W/cm2 with a large distance range from meter to kilometers. The strong laser field induces ionization and fragmentation of molecules in the laser propagation path, resulting in characteristic fingerprint emissions. This paper mainly focuses on recent research advances in environmental sensing by using femtosecond laser pulses through strong‐field‐induced ionization and fragmentation of molecules. The fingerprint emissions of molecules in strong laser fields are discussed based on the understanding of strong‐field–molecule interactions in atmospheric as well as in vacuum environments. This is followed by a comprehensive review of several recently developed optical methods for coherent control of fingerprint emissions of molecules. Lastly, both current challenges and a future perspective of this dynamic field are discussed. This article overviews recent research advances in environmental sensing by using femtosecond laser pulses through strong‐field‐induced ionization and fragmentation of molecules, which provides the possibility to induce the photoemission for a large number of molecular species of interest in the laser propagation path with only one single laser, and also opens up a way towards sensing “dark species” that emit light after ionization and fragmentation.