Submillimeter-wave measurements of the pressure broadening of BrO

Abstract

The N 2 and O 2 pressure broadening coefficients of the J=23.5←22.5 and J=25.5←24.5 rotational transitions in the ground vibronic state X 2 Π 3/2 of 81 BrO at 624.768 and 650.178 GHz have been independently measured at Ibaraki University and Jet Propulsion Laboratory. These lines are expected to be monitored by the superconducting submillimeter-wave limb emission sounder in the Japanese Experiment Module on the International Space Station (JEM/SMILES) as well as the earth observing system microwave limb sounder (EOS-MLS). This work provides temperature-dependent pressure broadening parameters of BrO needed by the space station and satellite based observations. The BrO pressure broadening coefficients and their 1 σ uncertainties are: γ 0( N 2)=3.24±0.05 MHz/Torr and γ 0( O 2)=2.33±0.06 MHz/Torr for the 624.768 GHz transition at room temperature (296 K) . For the 650.178 GHz line, the results are: γ 0( N 2)=3.20±0.07 MHz/Torr and γ 0( O 2)=2.41±0.06 MHz/Torr . The temperature dependence exponents and their 1 σ error are determined to be: n(N 2)=−0.76±0.05 and n(O 2)=−0.93±0.07 for the 624.768 GHz transition, and n(N 2)=−0.84±0.07 and n(O 2)=−0.70±0.07 for the 650.178 GHz transition.