Ultrafast dynamics of isolated phenylcarbenes followed by femtosecond time-resolved velocity map imaging.
The ultrafast dynamics of two carbene model systems, chlorophenylcarbene (CPC) and trifluoromethylphenylcarbene (TFPC), has been studied in a molecular beam. Velocity map imaging aids optimizing the pyrolysis conditions for a clean generation of reactive intermediates by supersonic jet flash pyrolysis. The dynamics was followed in real time by time-resolved mass spectroscopy and photoion and photoelectron imaging. CPC was excited at 265 nm into the 3 (1)A' state, corresponding to excitation from a pi-orbital of the aromatic ring into the lowest unoccupied molecular orbital, which contains the p-orbital at the carbene center. The experimental results suggest a three step deactivation process in agreement with computations. TFPC exhibits two absorption bands in the 36,000 cm(-1) and 41,000 cm(-1) range and gives rise to very similar dynamics, although it has a triplet ground state. The experimental data were augmented by computations.
Noller
Bastian
B
Laboratoire Francis Perrin, CNRS URA 2453, CEA IRAMIS/Service des Photons, Atoms et Molecules, F-91191 Gif-sur-Yvette Cedex, France.
Poisson
Lionel
L
Maksimenka
Raman
R
Gobert
Oliver
O
Fischer
Ingo
I
Mestdagh
J M
JM