We describe a method for determining the number density of the alkali metal vapor by use of an evanescent wave in a single total internal reflection. The method is simple to use, and it has the following useful features: It is most suitable for determining the number density of dense (>1013 cm−3) alkali metal vapor and it permits the measurement of the alkali metal vapor number density in the vicinity (∼10−5 cm) of cell surfaces. Using this method, we measured the number density of Rb metal vapor in the vicinity (∼10−5 cm) of the cell wall in cells that contain only Rb metal and no buffer gas; we found that there is no systematic difference between the Rb number density near the surface and that in the bulk.
© 2001 Optical Society of America
(240.6490) Optics at surfaces : Spectroscopy, surface
(260.6970) Physical optics : Total internal reflection
(300.1030) Spectroscopy : Absorption
(300.6210) Spectroscopy : Spectroscopy, atomic
Kaifeng Zhao, Z. Wu, and H. M. Lai, "Optical determination of alkali metal vapor number density in the vicinity (∼10-5 cm ) of cell surfaces," J. Opt. Soc. Am. B 18, 1904-1910 (2001)