@article{Fitzpatrick:2011,
author = {Fitzpatrick, AE and Lincoln, CN and van, Wilderen LJ and van, Thor JJ},
journal = {The Journal of Physical Chemistry B},
title = {Pump-Dump-Probe and Pump-Repump-Probe Ultrafast Spectroscopy Resolves Cross Section of an Early Ground State Intermediate and Stimulated Emission in the Photoreactions of the Pr Ground State of the Cyanobacterial Phytochrome Cph1.},
url = {http://pubs.acs.org/doi/abs/10.1021/jp206298n},
year = {2011}
}

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TY  - JOUR
AB  - The primary photoreactions of the red absorbing ground state (Pr) of the cyanobacterial phytochrome Cph1 from Synechocystis PC 6803 involve C15=C16 Z-E photoisomerisation of its phycocyanobilin chromophore. The first observable ground state intermediate in pump-probe measurements of the photocycle, 'Lumi-R', is formed with picosecond kinetics, and involves excited state decay reactions that have 3 and 14 ps time constants. Here, we have studied the photochemical formation of the Lumi-R intermediate using multi pulse picosecond visible spectroscopy. Pump-dump-probe (PDP) and pump-repump-probe (PRP) experiments were carried out by employing two femtosecond visible pulses with 1, 14 and 160 ps delays, together with a broadband dispersive visible probe. The time delays between the two excitation pulses have been selected to allow interaction with the dominant (3 and 14 ps) kinetic phases of Lumi-R formation. The frequency dependence of the PDP and PRP amplitudes was investigated at 620 nm, 640 nm, 660 nm and 680 nm, covering excited state absorption (λmax = 620 nm), ground state absorption (λmax = 660 nm) and stimulated emission (λmax = 680 nm) cross sections. Experimental double difference transient absorbance signals (OD), from the PDP and PRP measurements required corrections to remove contributions from ground state repumping. The sensitivity of the resulting OD signals was systematically investigated for possible connectivity schemes and photochemical parameters. When applying a homogeneous (sequentially decaying) connectivity scheme in both the 3 and 14 ps kinetic phases, evidence for repumping of an intermediate that has an electronic ground state configuration (GSI) is taken from the dump-induced S1 formation with 620, 640 and 660 nm wavelengths and 1 and 14 ps repump delays. Evidence for repumping a GSI is also seen, for the same excitation wavelengths, when imposing a target connectivity scheme proposed in refs1,2 for the 1 ps repump d
AU  - Fitzpatrick,AE
AU  - Lincoln,CN
AU  - van,Wilderen LJ
AU  - van,Thor JJ
PY  - 2011///
TI  - Pump-Dump-Probe and Pump-Repump-Probe Ultrafast Spectroscopy Resolves Cross Section of an Early Ground State Intermediate and Stimulated Emission in the Photoreactions of the Pr Ground State of the Cyanobacterial Phytochrome Cph1.
T2  - The Journal of Physical Chemistry B
UR  - http://pubs.acs.org/doi/abs/10.1021/jp206298n
ER  - 

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