Knowledge Bank

The methyl $(CH3)$ radical was detected in the gas phase by using a tunable diode laser spectrometer. Bonds corresponding to $\nu 2=1\leftarrow 0,2\leftarrow 1,3\leftarrow 2$ were observed in the $590-750cm-1$ region. Over a hundred P, Q, and R branch lines were fitted by least squares to a standard vibration-rotation Hamiltonian, and the rotational constants, the centrifugal distortion constants, as well as the 3 band origins were determined accurately. The potential curve determined for the $\nu 2$ vibration from the 3 band origins indicates that the methyl radical is planar, without any potential hump at $Q2=0$.