Physical Review Letters
Hyperfine Polarization and Its Normal Gradient Coefficient of Rb87 Atoms in the Vicinity ( ∼10−5 cm ) of Coated and Uncoated Pyrex Glass Surfaces
Kaifeng Zhao, Z. Wu
Abstract
We have made regionally specific measurement of the hyperfine polarization $⟨\mathbit{S}\ifmmode\cdot\else\textperiodcentered\fi{}\mathbit{I}⟩$ of $^{87}\mathrm{R}\mathrm{b}$ atoms in the vicinity ($\ensuremath{\sim}{10}^{\ensuremath{-}5}\text{ }\mathrm{c}\mathrm{m}$) of coated and uncoated Pyrex glass surfaces. We find that the polarization near an uncoated surface decreases rapidly with decreasing distance from the surface whereas for a silicone-coated surface the polarization is independent of the distance from the surface. We have also determined the normal gradient coefficient ${\ensuremath{\mu}}_{\mathbit{S}\ifmmode\cdot\else\textperiodcentered\fi{}\mathbit{I}}$ of the hyperfine polarization in uncoated cells. In a representative uncoated cell, at a Rb density $7.35\ifmmode\times\else\texttimes\fi{}{10}^{13}\text{ }{\mathrm{c}\mathrm{m}}^{\ensuremath{-}3}$ and a pump beam intensity $1.3\text{ }\mathrm{W}/{\mathrm{c}\mathrm{m}}^{2}$, we find ${\ensuremath{\mu}}_{\mathbit{S}\ifmmode\cdot\else\textperiodcentered\fi{}\mathbit{I}}=24\ifmmode\pm\else\textpm\fi{}7\text{ }\ensuremath{\mu}{\mathrm{m}}^{\ensuremath{-}1}$.