1 research outputs found
Optically Controlled Molecular Switching of an Indolobenzoxazine-Type Photochromic Compound
Photochromic
forward (oxazine ring-opening) and backward (oxazine
ring-closing) switching dynamics of an indolobenzoxazine compound
were studied by femtosecond pumpārepumpāprobe technique.
A UV pulse was used to excite the ring-closed form of the photochromic
compound, causing a CāO bond cleavage and the formation of
a spectrally red-shifted isomer within a time scale of ca. 100 ps.
A successive, temporally delayed near-IR pulse, resonant to the red-most
absorption maximum of the ring-opened form, was used to reexcite the
molecular system, causing a fast photoinduced oxazine ring closure,
thereby āshort-circuitingā the normally nanosecond lasting
photocycle and returning ā¼6% of the molecules to the main molecular
ground state. Two possible models, involving the <i>S</i><sub>1</sub> excited state of the terminal photoproduct and its hot
ground state, are introduced to explain the pre- and post-reexcitation
spectral development and the photoinduced switching back mechanics