Broadening and shifting of Rb D1 and D2 line in low pressure vapor cell

Abstract

The absorption line of the alkali metal is unstable in the atomic vapor cell, which is usually affected by the temperature and vapor pressure of the cell. However, the line shifting and broadening of the alkali metal in the atomic vapor cell could severely essential effect to the atomic sensors. This paper has systematically measured the broadening and shifting effect of Rubidium D1 and D2 line when the pressure of buffer gas N2 is lower than 1 atm. The broadening coefficient of Rb D1 line on the N2 pressure is 35.4MHz/torr, while the D2 line on the N2 pressure is 21.2MHz/torr. When the N2 pressure is near 1 atm, the shifting coefficients are 30.4MHz/K and -45.4MHz/K for D1 and D2 line through linear fit, respectively. The method in this paper, measuring the width shifting and broadening of the alkali metal absorb line, provides a way to verify the actual inner pressure of the vapor cell.