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The kinetics and the reaction patterns of the HO3 + and H2O3 + ions toward a variety of inorganic and organic substrates have been investigated by using Fourier-transform ion cyclotron resonance (FT-ICR) spectrometry. The thermochemistry of the HO3 + and H2O3 + ions is evaluated from correlations between their proton transfer (PT) efficiencies and the proton affinity (PA) of the selected substrates. Similarly, thermochemical data on HO3 and H2O3 species are inferred from a comparison between the electron transfer (ET) efficiencies of their cationic counterparts and the standard ionization energies (IE) of the substrates. Thus, in striking contrast with most literature theoretical and empirical estimates, an experimental value of −1 ± 5 kcal mol-1 is obtained for the standard heat of formation of HO3. Accordingly, ground-state HO3 (2A) is thermochemically stable toward dissociation to HO(2Π) and O2(3Σg -), and therefore, its existence as a true intermediate in key ionic reactions occurring in the upper atmosphere cannot be excluded. The standard formation enthalpy of H2O3 + (198 ± 5 kcal mol-1) is evaluated by two independent approaches, while that of the HOOOH neutral molecule is estimated as ≤−26 kcal mol-1. The HO3 + ion displays a variegated chemistry. Depending of the nature of the reactive centers of the neutral substrate, the HO3 + ion may react as a Brønsted or a Lewis acid, as an oxenium ion or an oxygen-centered free radical. When all these pathways are thermochemically precluded, as with CO, a ligand swiching process takes place in HO3 + to give the CHO2 + ion, which may promote a three-step acid-catalyzed cycle for the O3 oxidation of CO to CO2 and O2. Likewise, the less reactive H2O3 + ion undergoes ligand swiching by water.

One- and two-color, mass-selected R2PI spectra of the S1<--S0 transitions in the bare chiral chromophore R-(+)-1-phenyl-1-propanol (R) and its complexes with a variety of alcoholic solvent molecules (solv), namely methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, S-(+)-2-butanol, R-(-)-2-butanol, 1-pentanol, S-(+)-2-pentanol, R-(-)-2-pentanol, and 3-pentanol, were recorded after a supersonic molecular beam expansion. Spectral analysis, coupled with theoretical calculations, indicate that several hydrogen-bonded [R.solv] conformers are present in the beam. The R2PI excitation spectra of [R.solv] are characterized by significant shifts of their band origin relative to that of bare R. The extent and direction of these spectral shifts depend on the structure and configuration of solv and are attributed to different short-range interactions in the ground and excited [R.solv] complexes. Measurement of the binding energies of [R.solv] in their neutral and ionic states points to a subtle balance between attractive (electrostatic and dispersive) and repulsive (steric) forces, which control the spectral features of the complexes and allow enantiomeric discrimination of chiral solv molecules.

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The elusive protonated ozone ion (O(3)H(+)) has been long postulated as a reactive intermediate but never experimentally observed. This ion has been detected here in mass spectrometric experiments with the use of Fourier transform ion cyclotron resonance. In these experiments, ozone (O(3)) was protonated by strong acids-for example, H(3)(+), KrH(+), XeH(+), and CH(5)(+). The hitherto experimentally unknown proton affinity of O(3) was evaluated by a "bracketing" technique and determined to be 148 -/+ 3 kilocalories mole(-1) at 298 kelvin, in excellent agreement with a value determined in a recent theoretical study of the O(3)/O(3)H(+) system, which was 148 kilocalories mole(-1) at zero temperature ( approximately 149.5 kilocalories mole(-1) at 298 kelvin).