The low temperature reaction between CN and benzene ( C _ { 6 } H _ { 6 } ) is of significant interest in the astrochemical community due to the recent detection of benzonitrile , the first aromatic molecule identified in the interstellar medium ( ISM ) using radio astronomy .
Benzonitrile is suggested to be a low temperature proxy for benzene , one of the simplest aromatic molecules , which may be a precursor to polycyclic aromatic hydrocarbons ( PAHs ) .
In order to assess the robustness of benzonitrile as a proxy for benzene , low temperature kinetics measurements are required to confirm whether the reaction remains rapid at the low gas temperatures found in cold dense clouds .
Here , we study the C _ { 6 } H _ { 6 } + CN reaction in the temperature range 15–295 K , using the well-established CRESU technique ( a French acronym standing for Reaction Kinetics in Uniform Supersonic Flow ) combined with Pulsed Laser Photolysis-Laser-Induced Fluorescence ( PLP-LIF ) .
We obtain rate coefficients , k ( T ) , in the range ( 3.6–5.4 ) \times 10 ^ { -10 } cm ^ { 3 } s ^ { -1 } with no obvious temperature dependence between 15–295 K , confirming that the CN + C _ { 6 } H _ { 6 } reaction remains rapid at temperatures relevant to the cold ISM .