Measurements of Low Temperature Rate Coefficients for the Reaction of CH with CH${}_2$O and Application to Dark Cloud and AGB Stellar Wind Models

Abstract

Rate coefficients have been measured for the reaction of CH radicals with formaldehyde, CH${}_2$O, over the temperature range 31 - 133 K using a pulsed Laval nozzle apparatus combined with pulsed laser photolysis and laser induced fluorescence spectroscopy. The rate coefficients are very large and display a distinct decrease with decreasing temperature below 70 K, although classical collision rate theory fails to reproduce this temperature dependence. The measured rate coefficients have been parameterized and used as input for astrochemical models for both dark cloud and AGB stellar outflow scenarios. The models predict a distinct change (up to a factor of two) in the abundance of ketene, H${}_2$CCO, which is the major expected molecular product of the CH + CH${}_2$O reaction.

17 pages, 9 Figures, 5 Tables, Accepted for publication in The Astrophysical Journal

References in corpus (3)

• The 2014 KIDA network for interstellar chemistry
• An ALMA Early Science survey of molecular absorption lines toward PKS1830-211 -- Analysis of the absorption profiles
• Upper limits for undetected trace species in the stratosphere of Titan

Cited by in corpus (4)

• Discovery of the 7-ring PAH Cyanocoronene (C${}_{24}$H${}_{11}$CN) in GOTHAM Observations of TMC-1
• ATOMIUM: ALMA tracing the origins of molecules in dust forming oxygen rich M-type stars: Motivation, sample, calibration, and initial results
• The gas-phase reaction of NH2 with formaldehyde (CH2O) is not a source of formamide (NH2CHO) in interstellar environments
• Design and Implementation of a New Apparatus for Astrochemistry: Kinetic Measurements of the CH + OCS Reaction and Frequency Comb Spectroscopy in a Cold Uniform Supersonic Flow