Symmetry and lifetime of the hydroxymethyl radical in the 3p Rydberg state

Hydroxymethyl (CH2OH) radicals were produced in a molecular beam via the photoinitiated reaction between Cl atoms and methanol. The rovibronic spectrum obtained following excitation to the 3p Rydberg state was measured by (1+1) and (2+1) REMPI. Analyses of rotational contours of selected vibronic bands obtained in the molecular beam and in a flow cell led to the assignment of the excited Rydberg state as 2A″(3pz). The 11±2 cm−1 homogeneous linewidth that best fits the observed contours implies a lifetime of the excited state of 0.5±0.1 ps, consistent with predissociative decay.