Submillimeter-wave measurements of N₂ and O₂ pressure broadening for HO₂ radical generated by Hg-photosensitized reaction

详细信息    查看全文

• 作者：A. Mizoguchi ; ^{mizo@phys.titech.ac.jp} ; T. Yagi¹ ; K. Kondo ; T.O. Sato² ; H. Kanamori ^{kanamori@phys.titech.ac.jp}
• 关键词：Perhydroxyl radical ; Linewidths ; Pressure broadening ; Atmospheric spectra
• 刊名：Journal of Quantitative Spectroscopy and Radiative Transfer
• 出版年：2012
• 出版时间：March, 2012
• 年：2012
• 卷：113
• 期：4
• 页码：279-285
• 全文大小：688 K

文摘

The N₂ and O₂ pressure broadening coefficients of the pure rotational transitions at 625.66 GHz (N_KaKc=10_1?-10_0?0, J=10.5-10.5) and 649.70 GHz (N_KaKc=10_2?-9_2?, J=9.5-8.5) in the vibronic ground state X²A?of the perhydroxyl (HO₂) radical have been determined by precise laboratory measurements. For the production of HO₂, the mercury-photosensitized reaction of the H₂ and O₂ precursors was used to provide an optimum condition for measurement of the pressure broadening coefficient. The Superconducting Submillimeter-wave Limb Emission Sounder (SMILES) was designed to monitor the volume mixing ratio of trace gases including HO₂ in the Earth's upper atmosphere using these transitions. The precise measurement of pressure broadening coefficient ¦Ã in terms of the half width at half maximum is required in order to retrieve the atmospheric volume mixing ratio. In this work, ¦Ã coefficients of the 625.66 GHz transition were determined for N₂ and O₂ at room temperature as ¦Ã(N₂)=4.085¡À0.049 MHz/Torr and ¦Ã(O₂)=2.578¡À0.047 MHz/Torr with 3¦Ò uncertainty. Similarly, the coefficients of the 649.70 GHz transition were determined as ¦Ã(N₂)=3.489¡À0.094 MHz/Torr and ¦Ã(O₂)=2.615¡À0.099 MHz/Torr. The air broadening coefficients for the 625.66 GHz and 649.70 GHz lines were estimated at ¦Ã(air)=3.769¡À0.067 MHz and 3.298¡À0.099 MHz respectively, where the uncertainty includes possible systematic errors. The newly determined coefficients are compared with previous results and we discuss the advantage of the mercury-photosensitized reaction for HO₂ generation. In comparison with those of other singlet molecules, the pressure broadening coefficients of the HO₂ radical are not much affected by the existence of an unpaired electron.