HIGH-RESOLUTION SPECTROSCOPY OF HOBr IN THE FAR- AND NEAR-INFRARED

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 Title: HIGH-RESOLUTION SPECTROSCOPY OF HOBr IN THE FAR- AND NEAR-INFRARED Creators: Orphal, J.; Kou, Q.; Tchana, F. Kwabia; Pirali, O.; Flaud, J.- M. Issue Date: 2003 Abstract: Hypobromous acid, HOBr, is an important species in atmospheric chemistry. In the stratosphere it is mainly produced by the reaction between BrO and $HO_{2}$ but rapidly photolyzed by sunlight. In the marine troposphere it is also formed by heterogeneous reactions on sea-salt aerosols and is thus involved in the transport of bromine from the oceans into the atmosphere. Attempts to measure atmospheric HOBr concentrations have been $made^{a}$ using its far-infrared rotational transitions. In order to provide accurate line positions and intensities in this region we have measured high-resolution Fourier-transform absorption spectra of gaseous HOBr between $100-350 cm^{-1}$ using the Bruker IFS-120 HR at LPPM in Orsay. We have been able to improve the rotational-vibrational parameters of the ground $states^{b}$ and of the $\nu_{3}$ bands of $HO^{79}Br$ and $HO^{81}Br$ around $620 cm^{-1}$. For the rotational line intensities we have taken into account the Herman-Wallis effects. Furthermore, we have measured high-resolution absorption spectra of the $2\nu_{1}$ bands around 1.4 $\mu$m and determined their rotational-vibrational parameters. These overtone bands are observed to be even stronger than the $\nu_{3}$ fundamental bands, in agreement with ab-initio $calculations^{c}$. The results might be useful for detection of atmospheric HOBr using Cavity Ring-Down Spectroscopy with telecommunication diode-lasers operating at room temperature. URI: http://hdl.handle.net/1811/21035 Other Identifiers: 2003-TG-13