Electronic spectra in the 2100–2500 Å region, were reported for the allyl radical, the β-methallyl radical the α-methallyl radical, the β-ethallyl radical and the cyclopentenyl radical.The vibrational structures of the allyl and β substituted radicals indicate that in the main regions of absorption, the α(C—H) stretching frequency is excited. A single band progression observed in flashed allyl cyanide, was tentatively assigned to a free radical derived from pyrrole.