title: Long-lived coherent oscillations of the femtosecond transients in cyanobacterial photosystem I.
abstract: The pulsed excitation of electronic levels coupled to specific nuclear modes by a 26 fs laser pulse at 706 nm creates a wavepacket in the nuclear space of photopystem I (PS I) of Synechocystis sp. strain PCC 6803 both in the ground state and in the one-exciton manifold. Fourier transform of transient decay curves shows several low frequency peaks. The most prominent Power Spectral Density (PSD) peaks are at omega = 49 cm(-1) and omega = 88 cm(-1). The peculiarity of the coherent wavepacket in the PS I of S. sp. strain PCC 6803 is the unique, long-lived 49 cm(-1) and 88 cm(-1) oscillations with decay times up to 10 ps. It was suggested that such a long-lived coherence is determined by a contribution of the ground state wavepacket. The dependence of these two PSD peaks on the probe wavelength resembles the profile of the transient absorption spectra of PS I. The pump-probe signal in the Soret region reflects the dynamics of the ground state wavepacket created by pulsed excitation of the Q(y)-band. It was shown that the multimode Brownian oscillator model allows a quantitative fit of the oscillatory patterns of the pump-probe signal to be obtained.
authors.affiliation: N N Semenov Institute of Chemical Physics, Russian Academy of Sciences, Kosigin str 4, Moscow, Russia.
authors.forename: Oleg M
authors.initials: OM
authors.lastname: Sarkisov
authors.forename: Fedor E
authors.initials: FE
authors.lastname: Gostev
authors.forename: Ivan V
authors.initials: IV
authors.lastname: Shelaev
authors.forename: Vladimir I
authors.initials: VI
authors.lastname: Novoderezhkin
authors.forename: Oxana A
authors.initials: OA
authors.lastname: Gopta
authors.forename: Mahir D
authors.initials: MD
authors.lastname: Mamedov
authors.forename: Alexey Yu
authors.initials: AY
authors.lastname: Semenov
authors.forename: Victor A
authors.initials: VA
authors.lastname: Nadtochenko
mesh_terms: D007834:Lasers; D008027:Light; D009991:Oscillometry; D010782:Photolysis; D045331:Photosystem I Protein Complex / Q000737:chemistry* / Q000528:radiation effects; D011789:Quantum Theory; D046939:Synechocystis / Q000201:enzymology* / Q000528:radiation effects; D013997:Time Factors
chemical_list: D045331:Photosystem I Protein Complex