No abstract

Table S3 The equilibrium constants of the relevant complexes HOH2O, H2OHO, H2OHNO2, HNO2H2O, HNO2(H2O)2, HNO2(H2O)2a, HO(H2O)2, HO(H2O)2a, HNO2(H2O)3, HNO2(H2O)3a, HO(H2O)3, HO(H2O)3a at 240 -325 K. a, b a Equilibrium constants in units of cm 3 molecule -1 .b All equilibrium constants were calculated by using energies computed at the CCSD(T)/aug-cc-pVTZ level and partition functions obtained at the B3LYP/6-311+G(3df,2dp) level. c The concentration of the corresponding complexes at 298 K.•••(H2O)2a 240 5.48×10 -22 5.06×10 -21 2.35×10 -23 8.20×10 -23 1.09×10 -16 6.92×10 -17 250 4.56×10 -22 3.61×10 -21 2.02×10 -23 7.06×10 -23 3.77×10 -17 2.32×10 -17 278 2.97×10 -22 1.61×10 -21 1.43×10 -23 5.00×10 -23 2.92×10 -18 1.68×10 -18 288 2.61×10 -22 1.26×10 -21 1.30×10 -23 4.52×10 -23 1.32×10 -18 7.45×10 -19 298 2.32×10 -22 1.00×10 -21 1.19×10 -23 4.13×10 -23 6.35×10 -19 3.50×10 -19 308 2.08×10 -22 8.08×10 -22 1.09×10 -23 3.80×10 -23 3.20×10 -19 1.73×10 -19 325 1.77×10 -22 5.83×10 -22 9.68×10 -24 3.37×10 -23 1.10×10 -19 5.78×10 -201.89×10 -19 2.03×10 -19 9.58×10 -16 1.41×10 -15 3.81×10 -18 4.26×10 -18 250 9.53×10 -20 1.04×10 -19 3.28×10 -16 4.96×10 -16 1.80×10 -18 2.06×10 -18 278 1.83×10 -20 2.09×10 -20 2.50×10 -17 4.03×10 -17 2.94×10 -19 3.58×10 -19 288 1.10×10 -20 1.28×10 -20 1.13×10 -17 1.86×10 -17 1.68×10 -19 2.09×10 -19 298 6.80×10 -21 8.03×10 -21 5.39×10 -18 9.08×10 -18 9.95×10 -20 1.26×10 -19 308 4.36×10 -21 5.22×10 -21 2.71×10 -18 4.65×10 -18 6.11×10 -20 7.87×10 -20 325 2.18×10 -21 2.67×10 -21 9.31×10 -19 1.64×10 -18 2.86×10 -20 3.79×10 -20

A detailed theoretical study on the reaction mechanisms for the formations of H 2 O 2 + 3 O 2 from the self-reaction of HO 2 radicals under the effect of NH 3 , H 3 NÁÁÁH 2 O, and H 2 SO 4 catalysts was performed using the CCSD(T)/CBS//M06-2X/ aug-cc-pVTZ method. The rate constant was computed using canonical variational transition state theory (CVT) with small curvature tunneling (SCT). Our results indicate that NH 3-, H 3 NÁÁÁH 2 O-, and H 2 SO 4-catalyzed reactions could proceed through both one-step and stepwise routes. Calculated rate constants show that the catalyzed routes in the presence of the three catalysts all prefer stepwise pathways. Compared to the catalytic efficiency of H 2 O, the efficiencies of NH 3 , H 3 NÁÁÁH 2 O, and H 2 SO 4 are much lower due to their smaller relative concentrations. The present results have provided a definitive example of how basic and acidic catalysts influence the atmospheric reaction of HO 2 + HO 2 ! H 2 O 2 + 3 O 2. These results further encourage one to consider the effects of basic and acidic catalysts on the related atmospheric reactions. Thus, the present investigation should have broad implications in the gas-phase reactions of the atmosphere.