Dissociative excitation transfer in the reaction of O2(a1Δg) with OH−(H2O)1,2 clusters

Abstract

Rate constants for the dissociation of OH(-)(H(2)O) and OH(-)(H(2)O)(2) by transfer of electronic energy from O(2)(a(1)Delta(g)) were measured. Values of 1.8x10(-11) and 2.2x10(-11) cm(3) molecule(-1) s(-1), respectively, at 300 K were derived and temperature dependences were obtained from 300 to 500 K for OH(-)(H(2)O) and from 300 to 400 K for OH(-)(H(2)O)(2). Dissociative excitation transfer with OH(-)(H(2)O) is slightly endothermic and the reaction appears to have a positive temperature dependence, but barely outside the uncertainty range. In contrast, the reaction of OH(-)(H(2)O)(2) is exothermic and appears to have a negative temperature dependence. The rate constants are analyzed in terms of unimolecular rate theory, which suggests that the dissociation is prompt and is not affected by collisions with the helium buffer gas.

Capturing Transient Endoperoxide in the Singlet Oxygen Oxidation of Guanine

“…Viggiano et al. discovered that in the reaction of OH − (H 2 O)+ 1 O 2 excitation transfer‐induced water dissociation followed a direct collision mechanism . By assuming that similar direct excitation transfer‐induced water dissociation occurred in the collision of [G−H] − (H 2 O) with 1 O 2 , this would account for 22 % of the trajectories in which 1 O 2 attacked the water ligand directly.…”

Photochemistry of Ions at D-region Altitudes of the Ionosphere: A Review

“…Power-law temperature dependences T n 2 and T n -2 are recommended for the reaction rate coefficients of OH -(H 2 O) and OH -(H 2 O) 2 ions with O 2 ( 1 D g ), respectively (Viggiano et al 2009). …”

“…The measured value of this rate coefficient can be affected by reactions of vibrationally excited OH -ions with O 2 ( 1 D g ) (Viggiano et al 2009). …”

“…The OH -(H 2 O) ?O 2 ( 1 D g ) and OH -(H 2 O) 2 ?O 2 ( 1 D g ) reaction rate coefficients were measured by Viggiano et al (2009) at 300, 400, and 500 K temperatures for the first reaction and at 300 and 400 K temperatures for the second reaction with the experimental errors of about ±40 %. Power-law temperature dependences T n 2 and T n -2 are recommended for the reaction rate coefficients of OH -(H 2 O) and OH -(H 2 O) 2 ions with O 2 ( 1 D g ), respectively (Viggiano et al 2009).…”

“…The OH À þ O 2 ð 1 D g Þ reaction rate coefficient was measured by Viggiano et al (2009) at 300, 400, and 500 K temperatures. The measured value of this rate coefficient can be affected by reactions of vibrationally excited OH -ions with O 2 ( 1 D g ) (Viggiano et al 2009).…”