Water Vapor: An Extraordinary Terahertz Wave Source under Optical Excitation

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dc.creatorJohnson, Keith
dc.creatorPrice-Gallagher, Matthew
dc.creatorMamer, Orval
dc.creatorLesimple, Alain
dc.creatorFletcher, Clark
dc.creatorChen, Yunqing
dc.creatorLu, Xiaofei
dc.creatorYamaguchi, Masashi
dc.creatorZhang, X. -C.
dc.date2009-02-12
dc.date.accessioned2026-07-07T12:55:27Z
dc.date.available2026-07-07T12:55:27Z
dc.descriptionIn modern terahertz (THz) sensing and imaging spectroscopy, water is considered a nemesis to be avoided due to strong absorption in the THz frequency range. Here we report the first experimental demonstration and theoretical implications of using femtosecond laser pulses to generate intense broadband THz emission from water vapor. When we focused an intense laser pulse in water vapor contained in a gas cell or injected from a gas jet nozzle, an extraordinarily strong THz field from optically excited water vapor is observed. Water vapor has more than 50% greater THz generation efficiency than dry nitrogen. It had previously been assumed that the nonlinear generation of THz waves in this manner primarily involves a free-electron plasma, but we show that the molecular structure plays an essential role in the process. In particular, we found that THz wave generation from H2O vapor is significantly stronger than that from D2O vapor. Vibronic activities of water cluster ions, occurring naturally in water vapor, may possibly contribute to the observed isotope effect along with rovibrational contributions from the predominant monomers.
dc.description5 pages, 4 figures
dc.identifierhttps://arxiv.org/abs/0902.2024
dc.identifierhttp://arxiv.org/abs/0902.2024
dc.identifierPhys.Lett.A372:6037,2008
dc.identifierdoi:10.1016/j.physleta.2008.07.071
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/224254
dc.subjectOptics
dc.subjectCosmology and Nongalactic Astrophysics
dc.subjectMaterials Science
dc.subjectAtomic and Molecular Clusters
dc.titleWater Vapor: An Extraordinary Terahertz Wave Source under Optical Excitation
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