In our laboratory we have started a systematic investigation of several reactions involving atomic oxygen and unsaturated hydrocarbons (C2H2, C2H4, CH3CCH, CH2:C:CH2) by means of the crossed molecular beam technique with mass spectrometric detection and time-of-flight analysis.Quite interestingly, we have observed that C-C bond fission channels are always relevant or dominant reaction pathways. The most illustrative case is the reaction between O and allene (CH2:C:CH2) where about the 90% of the reaction leads directly to the stable products CO+C2H4, but also significant fractions of the reactions O+C2H2 and O+C2H4 lead to the products CO+CH2 and HCO+CH3, respectively. In other words, the reactions of unsaturated hydrocarbons with atomic oxygen are not only terminating the hydrocarbon growth in oxygen-rich environments, but are also able to convert relatively abundant and widely spread small unsaturated hydrocarbons directly into CO or its precursor HCO. Implications for the chemistry of the planetary atmospheres and interstellar medium will be noted.
The reactions of atomic oxygen with unsaturated hydrocarbons in extraterrestrial environments
BALUCANI, Nadia;LEONORI, FRANCESCA;FALCINELLI, Stefano;CASAVECCHIA, Piergiorgio
2012
Abstract
In our laboratory we have started a systematic investigation of several reactions involving atomic oxygen and unsaturated hydrocarbons (C2H2, C2H4, CH3CCH, CH2:C:CH2) by means of the crossed molecular beam technique with mass spectrometric detection and time-of-flight analysis.Quite interestingly, we have observed that C-C bond fission channels are always relevant or dominant reaction pathways. The most illustrative case is the reaction between O and allene (CH2:C:CH2) where about the 90% of the reaction leads directly to the stable products CO+C2H4, but also significant fractions of the reactions O+C2H2 and O+C2H4 lead to the products CO+CH2 and HCO+CH3, respectively. In other words, the reactions of unsaturated hydrocarbons with atomic oxygen are not only terminating the hydrocarbon growth in oxygen-rich environments, but are also able to convert relatively abundant and widely spread small unsaturated hydrocarbons directly into CO or its precursor HCO. Implications for the chemistry of the planetary atmospheres and interstellar medium will be noted.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
