Issue 38, 2022

Reaction of OH radicals with CH3NH2 in the gas phase: experimental (11.7–177.5 K) and computed rate coefficients (10–1000 K)

Abstract

Nitrogen-bearing molecules, like methylamine (CH3NH2), can be the building blocks of amino acids in the interstellar medium (ISM). At the ultralow temperatures of the ISM, it is important to know its gas-phase reactivity towards interstellar radicals and the products formed. In this work, the kinetics of the OH + CH3NH2 reaction was experimentally and theoretically investigated at low- and high-pressure limits (LPL and HPL) between 10 and 1000 K. Moreover, the CH2NH2 and CH3NH yields were computed in the same temperature range for both pressure regimes. A pulsed CRESU (French acronym for Reaction Kinetics in a Uniform Supersonic Flow) apparatus was employed to determine the rate coefficient, k(T), in the 11.7–177.5 K range. A drastic increase of k(T) when the temperature is lowered was observed in agreement with theoretical calculations, evaluated by the competitive canonical unified statistical (CCUS) theory, below 300 K in the LPL regime. The same trend was observed in the HPL regime below 350 K, but the theoretical k(T) values were higher than the experimental ones. Above 200 K, the calculated rate coefficients are improved with respect to previous computational studies and are in excellent agreement with the experimental literature data. In the LPL, the formation of CH3NH becomes largely dominant below ca. 100 K. Conversely, in the HPL regime, CH2NH2 is the only product below 100 K, whereas CH3NH becomes dominant at 298 K with a branching ratio similar to the one found in the LPL regime (≈70%). At T > 300 K, both reaction channels are competitive independently of the pressure regime.

Graphical abstract: Reaction of OH radicals with CH3NH2 in the gas phase: experimental (11.7–177.5 K) and computed rate coefficients (10–1000 K)

Supplementary files

Article information

Article type
Paper
Submitted
25 Jul 2022
Accepted
05 Sep 2022
First published
06 Sep 2022

Phys. Chem. Chem. Phys., 2022,24, 23593-23601

Reaction of OH radicals with CH3NH2 in the gas phase: experimental (11.7–177.5 K) and computed rate coefficients (10–1000 K)

D. González, A. Lema-Saavedra, S. Espinosa, E. Martínez-Núñez, A. Fernández-Ramos, A. Canosa, B. Ballesteros and E. Jiménez, Phys. Chem. Chem. Phys., 2022, 24, 23593 DOI: 10.1039/D2CP03414J

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements