Uptake of NH₃ and NH₃ + HOBr Reaction on Ice Surfaces at 190 K

Abstract

The uptake of NH3 and the heterogeneous reaction of NH3 + HOBr --> products on ice surfaces at 190 K have been investigated in a flow reactor coupled with a differentially pumped quadrupole mass spectrometer. The uptake coefficient gammat for NH3 was determined to be (3.8 +/- 1.4) x 10(-4) on ice films at 189.8 K, for a partial pressure of NH3 in the range of 7.0 x 10(-7) to 3.8 x 10(-6) torr. The amount of NH3 uptake on the ice film was determined to be >2.9 x 10(15) molecules/cm(2), based on the total ice surface area at 189.2 K. The heterogeneous reaction of NH3 + HOBr on ice surfaces has been studied at 190 K. The reaction probability gammat was determined to be (5.3 +/- 2.2) x 10(-4) and was found to vary insignificantly as HOBr surface coverage changes from 2.1 x 10(13) to 2.1 x 10(14) molecules/cm(2). A reaction pathway is proposed on the basis of experimental observations.

Characterization of soluble bromide measurements and a case study of BrO observations during ARCTAS

“…Gas phase HOBr was prepared by adding 5-7 drops of liquid Br 2 to silver nitrate (AgNO 3 ) aqueous solution (2.2g AgNO 3 in 100 mL de-ionized H 2 O) in a glass trap that was kept at 0 • C in the dark (Jin et al, 2007). The AgNO 3 is used to precipitate out Br − as silver bromide (AgBr).…”

Hydrogen bonded structure and dynamics of liquid-vapor interface of water-ammonia mixture: An ab initio molecular dynamics study

“…[1][2][3][4][5] It is also required for various heterogeneous catalysis and other industrial applications. 5,6 There have been a number studies on the structure and dynamics of liquid-vapor interfaces of water-ammonia mixtures or on uptake of ammonia at aqueous surfaces using experimental [7][8][9][10][11][12][13][14][15][16][17][18] and theoretical 14,[19][20][21][22][23] means. We note, in particular, the early study of Rice et al 7 where a surface complex formation between ammonia and water molecules was proposed based on surface-tension data.…”

The HOX⋯SO2 (X=F, Cl, Br, I) Binary Complexes: Implications for Atmospheric Chemistry

“…There is evidence certain halogen containing reactions might be made more efficient depending on their interactions with ice surfaces [1,41−46] . Previous studies suggest the reaction of sulfur dioxide with hypohalous acids (from here on referred to as HOX, with X=F, Cl, Br, and I) species on atmospheric ice surfaces may be a prime example of this [27,32] . Both SO 2 and HOX play substantial roles in atmospheric chemistry.…”

“…Atmospheric ice‐surface chemistry is a rapidly expanding research topic [1–27] . Many processes such as cloud nucleation, [6,28–32] ozone depletion, [1,5,8,11–13,15,17,18,20–26,32–35] and haze formation [36] are driven by chemical reactions influenced by the presence of stratospheric ice.…”