Laser absorption spectroscopy of water vapor confined in nanoporous alumina: wall collision line broadening and gas diffusion dynamics.

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Abstract

We demonstrate high-resolution tunable diode laser absorption spectroscopy (TDLAS) of water vapor confined in nanoporous alumina. Strong multiple light scattering results in long photon pathlengths (1 m through a 6 mm sample). We report on strong line broadening due to frequent wall collisions (gas-surface interactions). For the water vapor line at 935.685 nm, the HWHM of confined molecules are about 4.3 GHz as compared to 2.9 GHz for free molecules (atmospheric pressure). Gas diffusion is also investigated, and in contrast to molecular oxygen (that moves rapidly in and out of the alumina), the exchange of water vapor is found very slow.

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  • Atom and Molecular Physics and Optics
Original languageEnglish
Pages (from-to)16460-16473
JournalOptics Express
Volume18
Issue number16
Publication statusPublished - 2010
Publication categoryResearch
Peer-reviewedYes