Measurement of the scalar polarizability within the 5P1/2-6S1/2410-nm transition in atomic indium

Abstract

We have completed a measurement of the Stark shift in ${}^{115}$In within the 410-nm $5{P}_{1/2}$-$6{S}_{1/2}$ transition. We measure the Stark shift constant to be ${k}_{S}=\ensuremath{-}122.92(33)$ kHz/(kV/cm)${}^{2}$, corresponding to a difference in the $6{S}_{1/2}$- and $5{P}_{1/2}$-state polarizabilities, $\ensuremath{\Delta}{\ensuremath{\alpha}}_{0}$ (in atomic units), of $1000.2\ifmmode\pm\else\textpm\fi{}2.7\phantom{\rule{0.16em}{0ex}}{a}_{0}^{3}$. This result is a factor of 30 more precise than previous measurements and is in excellent agreement with a new theoretical value based on an ab initio calculation of the wave functions in this three-valence-electron system. The measurement was performed in an indium atomic-beam apparatus, used a GaN laser diode system, and exploited a FM spectroscopy technique to extract laser transmission spectra under conditions where our interaction region optical depth was typically less than 10${}^{\ensuremath{-}3}$.