Time-resolved study of mercury atom production and removal following the photolysis of HgBr2 at 193 nm

Photoreduction of gaseous oxidized mercury changes global atmospheric mercury speciation, transport and deposition

“…Nevertheless, a similar very efficient photodissociation step is to be expected for these mercury halides considering the even lower dissociation energies of the HgBr-X bond, as compared with that of the parent HgBr-Br dihalide (Supplementary Table 3 ) 9 , 27 . In addition to this primary photolysis reaction to HgBr, it has been shown that Hg(0) is also generated in the HgBr 2 photodissociation through direct or secondary channels, although to a much lesser extent 31 , 32 . Based on this evidence, we consider in the atmospheric modelling below that HgBr is the main product of HgBrX photodissociation, although we also ran one scenario where HgBrX photodissociation results in Hg(0) production.…”

The reaction between HgBr and O3: kinetic study and atmospheric implications

“…The experiments were performed at a range of pressures (Table 1) for which the recombination of Reaction (R6) has a rate constant of k 6 = 9.5 Â 10 À14 cm 3 molecule À1 s À1 at 200 torr and 298 K, 13 and therefore it is too slow to significantly regenerate HgBr on sub-second time scales. An upper limit of 5 Â 10 À16 cm 3 molecule À1 s À1 has been determined for the rate constant of reaction (R7), 46 which is also too slow. Reaction (R8a) is close to its highpressure limit at 1 bar, with a theoretical estimate of k 8a = 2.5 Â 10 À10 cm 3 molecule À1 s À1 at 298 K. 14 There are no estimates of this rate constant at pressures relevant for this study.…”

HgBr (B–X) formation due to collisions involving O+/ and HgBr2 at kinetic energies (lab.) above 100 eV

“…may take place leading to the formation of HgBrJ, HgBr + , Hg + , N + , N 2 , Ar + , Ar 2 , O + , O 2 etc. besides HgBr (B-state) formation during collisions involving these gases, electrons and HgBr 2 molecules (Nighan 1980;Burnham 1978;Leslie et al 1984;Schilowitz & Wiesenfeld 1982;Helvajian & Wittig 1981;Johnson & Biondi 1980). To study the collisional dynamics of the charge transfer processes involving A + and HgBr 2 molecules, the following reaction products are expected to be observed:…”