Catalytic effect of (H₂O)_n (n = 1–3) clusters on the HO₂ + SO₂ → HOSO + ³O₂ reaction under tropospheric conditions

Abstract

The HO2 + SO2 → HOSO + 3O2 reaction without and with (H2O)n (n = 1–3) have been investigated using CCSD(T)/CBS//M06-2X/aug-cc-pVTZ methods, and canonical variational transition state theory with small curvature tunneling.

Effect of NH3 and HCOOH on the H2O2 + HO → HO2 + H2O reaction in the troposphere: competition between the one-step and stepwise mechanisms

“…where K eq1a , K eq1d , and K eq1f respectively denote the equilibrium constant for the formation of H 55,64,65,70,75 The relative rates for v R_AM1 /v R_WM and v R_FA1 /v R_WM within the temperature range of 280-320 K are given in Table 3. As seen in Table 3, when the concentrations of H 2 O at 100% (2.60 Â 10 17 molecule per cm 3 to 2.30 Â 10 18 molecule per cm 3 ) 76 RH and NH 3 at 10 ppbv (2.60 Â 10 11 molecule per cm 3 to 2.30 Â 10 11 molecule per cm 3 ), [22][23][24] the calculated v R_AM1 /v R_WM value is below 2.47 Â 10 À3 to 9.40 Â 10 À5 within the temperature range…”

“…It should be noted that K eq2 calculated here has been successfully performed in calculating the complexes[61][62][63][64][65] of H 2 O/VOC, H 2 O/HCHO, H 2 O/CH 3 COCH 3 , H 2 O/CH 2 NH, H 2 O/HO 2 , H 2 O/SO 2 , and H 2 O/NO 2 .…”

Oxidation of HOSO˙ by O2 (3Σg−): a key reaction deciding the fate of HOSO˙ in the atmosphere

“…The aim of the present work is to study the reaction of HOSO with O 2 ( 3 S g À ) and assess its potential impact on the atmosphere. Although there are a few studies 21,22 in the literature which give indirect information about the title reaction, they lack the discussion of the potential impact of the title reaction on the atmosphere. For example, in 2005, Wang and Hou theoretically studied the mechanism of the SO 2 + HO 2 reaction (reverse of the title reaction) at the B3LYP/aug-cc-pV(T+d)Z level of theory.…”

“…Recently, in 2019, Wang et al investigated the catalytic effect of water clusters (H 2 O) n ( n = 1–3) on the SO 2 + HO 2 ˙ reaction employing the CCSD(T)/CBS//M06-2X/aug-cc-pVTZ level of theory. 22 In both of these studies, the emphasis was on the reverse reaction rather the title reaction. Interestingly, it is the forward reaction (HOSO˙ + O 2 ( 3 Σ g − )) which is exothermic in nature and hence thermodynamically more feasible.…”