| Summary: | We used the multichannel quantum defect theory to compute cross sections and rate coefficients for the dissociative recombination of CH<inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mo>+</mo> </msup> </semantics> </math> </inline-formula> initially in its lowest vibrational level <inline-formula> <math display="inline"> <semantics> <mrow> <msubsup> <mi>v</mi> <mi>i</mi> <mo>+</mo> </msubsup> <mo>=</mo> <mn>0</mn> </mrow> </semantics> </math> </inline-formula> with electrons of incident energy below <inline-formula> <math display="inline"> <semantics> <mrow> <mn>0.2</mn> </mrow> </semantics> </math> </inline-formula> eV. We have focused on the contribution of the 2 <inline-formula> <math display="inline"> <semantics> <mrow> <msup> <mrow></mrow> <mn>2</mn> </msup> <mo>Π</mo> </mrow> </semantics> </math> </inline-formula> state which is the main dissociative recombination route at low collision energies. The final cross section is obtained by averaging the relevant initial rotational states <inline-formula> <math display="inline"> <semantics> <mrow> <mo>(</mo> <msubsup> <mi>N</mi> <mi>i</mi> <mo>+</mo> </msubsup> <mo>=</mo> <mn>0</mn> <mo>,</mo> <mo>⋯</mo> <mo>,</mo> <mn>10</mn> <mo>)</mo> </mrow> </semantics> </math> </inline-formula> with a 300 K Boltzmann distribution. The Maxwell isotropic rate coefficients for dissociative recombination are also calculated for different initial rotational states and for electronic temperatures up to a few hundred Kelvins. Our results are compared to storage-ring measurements.
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