OH A 2Σ+ X 2Π chemiluminescence measurements of N2+, Ar+ + H2O hydrogen-atom-transfer reactions at suprathermal energies

DOI: 10.1063/1.463085

Source and publish data:

Journal of Chemical Physics p. 2473 - 2480 (1992)

Update date:2022-08-30

Topics:

Authors:

Gardner, James A.

Dressler, Rainer A.

Salter, Richard H.

Murad, Edmond

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Article abstract of DOI:10.1063/1.463085

Chemiluminescence attributable to OH A ²Σ⁺ <*> X ²Π emission is observed in hydrogen-atom transfer reactions of N2⁺ and Ar⁺ with H2O.High-resolution OH A <*> X spectra <0.5 nm full width a half maximum (FWHM) are presented as a function of collision energy in the range E_c.m. = 5-20 eV.The spectra clearly show an increase in rotational broadening with collision energy.To reasonably fit the spectral data, simulations require contributions from two Boltzmann distributions with different rotational temperatures.It is proposed that the OH A state is formed via two channels.In the dominant channel, A state OH is formed in both υ' = 0 and υ' = 1, with a collision energy-dependent rotational temperature ranging from 1000 K at E_c.m. = 6 eV to 3400 K at E_c.m. = 19 eV.The rotationally excited products are proposed to be formed in a two-step reaction involving charge transfer, followed by the transfer of a proton to the primary species.The second channel is characterized by formation of A state OH primarily in the υ' = 0 vibrational level with a rotational temperature of 300 K.Comparison of low-resolution (4 nm FWHM) OH A <*> X and H2O⁺ <*> ²A₁ <*> <*> ²B₁ emissions provides an estimate for the OH A state cross sections of ?<0.3*10^-16 cm² for N2⁺ + H2O at E_c.m. between 6 and 20 eV, representing less than 10percent of the hydrogen atom pickup channel at these energies.For Ar⁺ + H2O at E_c.m. between 11 and 32 eV, the estimated OH A state cross section is ?<0.5 Angstroem², which may represent all of the hydrogen atom pickup channel at the higher energies.