Research overview
The cyanomethyl radical (CH₂CN) is a reactive intermediate found in the interstellar medium, but its laboratory rotational spectrum had previously been measured only up to 280 GHz. This paper extends the measurements across the millimetre and sub-millimetre region, from 79 to 860 GHz, using a W-band chirped-pulse instrument and a frequency-multiplication-chain spectrometer. The radicals were produced at room temperature in a flow cell by hydrogen abstraction from acetonitrile with atomic fluorine. New transitions with N″ up to 42 and Ka″ up to 8 were combined with earlier data. This refines the spectroscopic parameters, especially the A rotational constant and the K-dependent terms, which were previously poorly determined. The resulting model reproduces all transitions to experimental accuracy and supports searches for the radical in cold to warm regions of the interstellar medium.
Key findings
- CH₂CN rotational spectrum measured from 79 to 860 GHz, extending beyond the previous 280 GHz limit
- Radicals produced by H-abstraction from acetonitrile with atomic fluorine at room temperature
- Transitions assigned with N″ up to 42 and Ka″ up to 8
- A rotational constant and K-dependent parameters significantly better determined
