Side-chain effects on the electronic relaxation of radicals followed by time-resolved pump-probe spectroscopy: 2,3-dimethylbut-2-yl vs tert-butyl.

J Phys Chem A

Laboratoire Francis Perrin, CNRS URA 2453, CEA IRAMIS/Service des Photos, Atoms et Molécules, F-91191 Gif-sur-Yvette Cedex, France.

Published: March 2010

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.

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http://dx.doi.org/10.1021/jp9062059DOI Listing

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