Abstract
We report the results of laboratory measurements of H2O2 production inside thin (50 nm thickness) H2O and H2O:O2 ice samples irradiated by 121.6 nm photons at different temperatures. In the case of H2O ice, H2O2 is formed at the temperatures below 60 К. In the case of H2O:O2 ice, H2O2 is formed in the 20–140 К range. For H2O:O2 = 9:1 ice, we derived H2O2 photochemical quantum yield as a function of sample irradiation temperature. The obtained data can be used for evaluation of H2O2 photoproduction at the surface of astrophysical water ice bodies and inside the particles of Noctilucent Clouds in the Earth’s atmosphere.
Highlights
We report the results of laboratory measurements of H2O2 production inside thin (50 nm thickness) H2O and H2O:O2 ice samples irradiated by 121.6 nm photons at different temperatures
This work reports the first results of laboratory measurements of H2O2 production inside thin H2O and H2O:O2 ice samples irradiated by 121.6 nm photons in the temperature range of 20–140 K
Hydrogen peroxide was found by detecting the IR absorption band of 2850–2860 cm−1 appeared in FTIR spectra of H2O and H2O:O2 ice samples as the result of their irradiation by calibrated source of 121.6 nm photons at high vacuum conditions
Summary
We report the results of laboratory measurements of H2O2 production inside thin (50 nm thickness) H2O and H2O:O2 ice samples irradiated by 121.6 nm photons at different temperatures. It is well known that surfaces of most icy bodies in the outer Solar System and interstellar space consist mainly of water and are regularly bombarded with energetic particles and photons This irradiation triggers a spectrum of physicochemical processes inside solid phase[1,2,3,4]: the formation of primary products (H, OH, H2, and О); their fast recombination or leaving from the initial position with subsequent diffusion inside ice; reactions between them, with H2O or impurities; appearance of secondary products (HO2, HO3, H2O2, O2, O3); trapping of primary and secondary products by the ice matrix and their accumulation; and the flow of products into gas phase. We discuss possible implications of the obtained results at the surface of astrophysical water ice bodies and inside the particles of Noctilucent Clouds in the Earth’s atmosphere. It is not doubt that clouds form by condensation of water vapour and can influence on gas-phase chemistry of this region due to water vapour is its key parameter
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