Collisional broadening of Ba I line (553.5 nm) by He or Ar

Abstract

The Doppler-free line shape of the 6s21S0 − 6s16p11P1 transition at 553.5 nm in natural Ba in the presence of an argon or helium buffer gas has been measured at 744 K for gas pressures from 0.2 to 100 Torr. Using the measured data for pressures above 5 Torr, the broadening rate coefficients for the half width at half maximum (HWHM) are determined to be (4.9±0.5)⊗10−9 and (5.0±0.5)⊗10−9 s−1 cm−3 for helium and argon respectively.