Determination of the branching ratio of CH${}_3$OH + OH reaction on water ice surface at 10 K

Abstract

The CH${}_3$O and CH${}_2$OH radicals can be important precursors of complex organic molecules (COMs) in interstellar dust. The COMs presumably originating from these radicals were abundantly found in various astronomical objects. Because each radical leads to different types of COMs, determining the abundance ratio of CH${}_3$O to CH${}_2$OH is crucial for a better understanding of the chemical evolution to various COMs. Recent work suggested that the reaction between CH${}_3$OH and OH on ice dust plays an important role in forming CH${}_3$O and CH${}_2$OH radicals. However, quantitative details on the abundance of these radicals have not been presented to date. Herein, we experimentally determined the branching ratio (CH${}_3$O/CH${}_2$OH) resulting from the CH${}_3$OH + OH reaction on the water ice surface at 10 K to be 4.3 $\pm$ 0.6. Furthermore, the CH${}_3$O product in the reaction would participate in subsequent diffusive reactions even at a temperature as low as 10 K. This fact should provide critical information for COMs formation models in cold molecular clouds.

Accepted in ApJ; 30 pages, 10 figures, 1 Table

References in corpus (15)

• Formation of methyl formate and other organic species in the warm-up phase of hot molecular cores
• Formation of complex organic molecules in cold objects: the role of gas phase reactions
• The origin of complex organic molecules in prestellar cores
• The Spatial Distribution of Complex Organic Molecules in the L1544 Pre-stellar Core
• Constraining the abundances of complex organics in the inner regions of solar-type protostars
• Experimental evidence for Glycolaldehyde and Ethylene Glycol formation by surface hydrogenation of CO molecules under dense molecular cloud conditions
• Formation of Complex Organic Molecules in Cold Interstellar Environments through non-diffusive grain-surface and ice-mantle chemistry
• The formation of ethylene glycol and other complex organic molecules in star-forming regions
• Detection of glycolaldehyde towards the solar-type protostar NGC1333 IRAS2A
• Production of complex organic molecules: H-atom addition versus UV irradiation
• Diffusion activation energy and desorption activation energy for astrochemically relevant species on water ice show no clear relation
• Tunneling Rate Constants for H2CO+H on Amorphous Solid Water Surfaces
• Transmission Electron Microscopy Study of the Morphology of Ices Composed of H2O, CO2, and CO on Refractory Grains
• Direct Determination of the Activation Energy for Diffusion of OH Radicals on Water Ice
• Methoxymethanol Formation Starting from CO-Hydrogenation

Cited by in corpus (2)

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