Ultrafast ring-closure reaction of photochromic indolylfulgimides studied with UV-pump-IR-probe spectroscopy.
The ring-opening and ring-closure reactions of a photochromic indolylfulgimide are investigated with femtosecond vibrational spectroscopy. Spectral signatures due to excited-state decay and vibrational cooling are seen in the mid-IR region. For the ring-opening reaction triggered with visible pulses, a lifetime of the excited electronic state of 4 ps was obtained in polar solution. In a nonpolar solvent, this time constant is reduced to 2 ps. The ring-closure reaction induced with UV pulses displays an excited-state lifetime and thus a building of the photoproduct of roughly 0.5 ps. For all processes, the subsequent cooling occurs on a 15-ps time scale lasting up to approximately 50 ps. The time-resolved IR measurements do not support the existence of any long-living intermediate states.
Koller
Florian O
FO
BioMolekulare Optik, Department für Physik, Munich-Centre for Advanced Photonics, Ludwig-Maximilians-Universität München, Oettingenstr. 67, D-80538 München, Germany.
Schreier
Wolfgang J
WJ
Schrader
Tobias E
TE
Malkmus
Stephan
S
Schulz
Christine
C
Dietrich
Steffen
S
Rück-Braun
Karola
K
Braun
Markus
M
D007094:Imides / Q000737:chemistry*; D007211:Indoles / Q000737:chemistry*; D007536:Isomerism; D015394:Molecular Structure; D010777:Photochemistry; D012997:Solvents; D013053:Spectrophotometry; D013997:Time Factors
D007094:Imides; D007211:Indoles; D012997:Solvents