Side-Chain Effects on the Electronic Relaxation of Radicals followed by Time-Resolved Pump−Probe Spectroscopy: 2,3-Dimethylbut-2-yl vs tert-Butyl

B. Noller (1, 2) , L. Poisson (1) , I. Fischer (2) , J.-M. Mestdagh (1)

1 LFP - URA 2453 - Laboratoire Francis PERRIN
2 Institut of Physical Chemistry

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-C4H9), 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.

Domaines: Chimie théorique et/ou physique

B. Noller, L. Poisson, I. Fischer, J.-M. Mestdagh. Side-Chain Effects on the Electronic Relaxation of Radicals followed by Time-Resolved Pump−Probe Spectroscopy: 2,3-Dimethylbut-2-yl vs tert-Butyl. Journal of Physical Chemistry A, 2010, 114 (9), pp.3045-3049. ⟨10.1021/jp9062059⟩. ⟨hal-00472738⟩