Info

" Goldfarb et al. (1997) unless otherwise indicated. h Yokelson et al. (1997).

' Minton et al. (1992); ratios converted to absolute values assuming a photodissociation quantum yield of 1 and only two channels.

'' Moore et al. (1995); ratios converted to absolute values assuming a photodissociation quantum yield of 1 and only two channels. ' Tyndall et al. (1997).

major pathway in the atmosphere; at 248 nm, the quantum yield of oxygen atoms was ~ 0.2, that for Br ~ 0.5, and that for BrO ~ 0.5 (Harwood et al., 1998).

O. HC1 AND HBr

Figure 4.33 shows the absorption cross sections of HC1 and HBr at room temperature (DeMore et al., 1997; Huebert and Martin, 1968). Neither absorb above 290 nm, so their major tropospheric fates are deposition or reaction with OH. Even in the stratosphere, photolysis is sufficiently slow that these hydrogen halides act as temporary halogen reservoirs (see Chapter 12).

N03 production has been observed in this system (Deters et al., 1998; Harwood et al., 1998). The quantum yields for N03 at 248, 308, and 352.5 nm have been reported to be 0.28 + 0.09, 1.01 + 0.35, and 0.92 + 0.43, respectively, indicating that channel (33b) is a

FIGURE 4.33 Absorption spectra of HC1 and HBr at room temperature (based on data in DeMore et al., 1997, and Huebert and Martin, 1968).

FIGURE 4.33 Absorption spectra of HC1 and HBr at room temperature (based on data in DeMore et al., 1997, and Huebert and Martin, 1968).

o c\j o
0 0

Post a comment