Rubidium excited state line shapes from 5P to 5D and 7S broadened by helium

Abstract Pump modulated laser absorption spectroscopy was used to measure five excited state line shapes for electric dipole allowed transitions beginning in the Rb 5 P manifold. Helium was used as the collisional buffer gas, with pressures from 0 to 250 Torr. Center frequency, FWHM, and asymmetry parameters were extracted from the fits and plotted versus pressure to determine rates. Lines terminating in the 5 D manifold had collisional broadening rates, γ , of 49.5–54.6 MHz/Torr, collisional shift rates, δ of less than ± 1.3  MHz/Torr, and asymmetry rates, β 0 , of less than ± 0.08  mrad/Torr. Lines terminating in the 7 2 S 1 / 2 state showed significantly higher rates, with broadening rates of 109.1–111.0 MHz/Torr, shift rates of 11.5–13.3 MHz/Torr, and asymmetry rates of 0.28–0.47 mrad/Torr. These trends qualitatively match numerically computed difference potentials, which also predict large rates for the 7 S lines and smaller rates for the 5 D lines.