Side-chain effects on the electronic relaxation of radicals followed by time-resolved pump-probe spectroscopy: 2,3-dimethylbut-2-yl vs tert-butyl.
The excited-state lifetime of the 2,3-dimethylbut-2-yl (DMB) radical, a hexyl isomer, upon electronic excitation into the 3p Rydberg state at 265 nm, is measured by femtosecond time-resolved photoionization. It is shown that the 3p state deactivates in a two-step process, which is well described by two time constants of 25 and 400 fs. The results are compared to tert-butyl (t-C(4)H(9)), another tertiary radical investigated before. Time-dependent DFT calculations confirm the earlier suggestion that curve crossings along the C-C coordinate play an important role in the excited-state deactivation.
Noller
Bastian
B
Laboratoire Francis Perrin, CNRS URA 2453, CEA IRAMIS/Service des Photos, Atoms et Molécules, F-91191 Gif-sur-Yvette Cedex, France.
Poisson
Lionel
L
Fischer
Ingo
I
Mestdagh
Jean-Michel
JM