Charge transfer reactions between gas-phase hydrated electrons, molecular oxygen and carbon dioxide at temperatures of 80–300 K

Abstract

The recombination reactions of gas-phase hydrated electrons (H2O)n˙(-) with CO2 and O2, as well as the charge exchange reaction of CO2˙(-)(H2O)n with O2, were studied by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry in the temperature range T = 80-300 K. Comparison of the rate constants with collision models shows that CO2 reacts with 50% collision efficiency, while O2 reacts considerably slower. Nanocalorimetry yields internally consistent results for the three reactions. Converted to room temperature condensed phase, this yields hydration enthalpies of CO2˙(-) and O2˙(-), ΔHhyd(CO2˙(-)) = -334 ± 44 kJ mol(-1) and ΔHhyd(O2˙(-)) = -404 ± 28 kJ mol(-1). Quantum chemical calculations show that the charge exchange reaction proceeds via a CO4˙(-) intermediate, which is consistent with a fully ergodic reaction and also with the small efficiency. Ab initio molecular dynamics simulations corroborate this picture and indicate that the CO4˙(-) intermediate has a lifetime significantly above the ps regime.

Infrared Spectroscopy of Size‐Selected Hydrated Carbon Dioxide Radical Anions CO2.−(H2O)n (n=2–61) in the C−O Stretch Region

“…The experiments were performed with a modified Bruker/Spectrospin CMS47X FT‐ICR (ion cyclotron resonance) mass spectrometer described in detail elsewhere, see also the Supporting Information for further details. Hydrated carbon dioxide radical anions CO 2 .− (H 2 O) n were generated in a laser vaporization source .…”

Communication: Charge transfer dominates over proton transfer in the reaction of nitric acid with gas-phase hydrated electrons

“…First, the finite size allows for a direct observation of various molecular fragments formed in the reactions by mass spectrometry. Second, the energetics of the reaction can be probed using the concept of nanocalorimetry, [7][8][9] i.e., by detecting the number of evaporating water molecules when the reaction takes place. The analogous reaction of (H 2 O) n with HCl was studied by Siu et al 10 As HCl is a very strong acid, proton transfer prevails.…”

“…We therefore applied the nanocalorimetry approach, in which the exothermicity of the reaction is determined via the average number of evaporated water molecules. [7][8][9] The mean cluster sizes for reactants and products as well as their difference are plotted as a function of time, Figs. 2(b) and 2(c), and fitted with a set of differential equations that account for the water loss due to reaction as well as BIRD.…”

Infrared Multiple Photon Dissociation Spectroscopy of Hydrated Cobalt Anions Doped with Carbon Dioxide CoCO2(H2O)n−, n=1–10, in the C−O Stretch Region

“…The experiments were performed on am odified 4.7 TF T-ICR Bruker/Spectrospin CMS47X mass spectrometer [64,[79][80][81][82] equipped with aB ruker infinity cell. [83] Ions are produced in an external laser vaporization source [84,85] with a3 0Hzp ulsed frequency doubled Nd:YAG laser (Litron Nano S6 0-30).…”

“…Nanocalorimetry revealed important details about the thermochemistry of the carbon dioxide radical anion,i np articular,i ts hydration enthalpy. [63,64] Raman spectroscopy of CO 2 À in bulk aqueous solution [65] places the symmetric stretching mode of hydrated CO 2 À at 1298 cm À1 .I no ur recent IR study on gas phase clusters CO 2 À (H 2 O) n ,w eo bservedv ery similarv alues already around n = 20. [14] Some hydrated metal ions M + (H 2 O) n ,M= Mg, Cr,C o, pick up exactly one CO 2 molecule, indicating that electron transfer from the metal to carbon dioxide takes place.…”