Excited-state decay of hydrocarbon radicals, investigated by femtosecond time-resolved photoionization: Ethyl, propargyl, and benzyl

The excited state decay of the hydrocarbon radicals ethyl, C 2H 5; propargyl, C 3H 3; and benzyl, C 7H 7 was investigated by femtosecond time-resolved photoionization. Radicals were generated by flash pyrolysis of n-propyl nitrite, propargyl bromide, and toluene, respectively. It is shown that the 2 2A ??? (3s) Rydberg state of ethyl excited at 250 nm decays with a time constant of 20 fs. No residual signal was observed at longer delay times. For the 3 2B 1 state of propargyl excited at 255 nm a slower decay with a time constant 50??10 fs was determined. The 4 2B 2 state of benzyl excited at 255 nm decays within 150??30 fs.open242