Structured hole-burned spectra of reaction centers of Rhodopseudomonas viridis

Abstract

Z)°(Cu2) = 2.01 ± 0.08 eV.4 These molecules are generally agreed to have (4sffg)2 bonds with weakly interacting 3d cores. Their diabatic dissociations lead to promotion energies of 0.06 and 0.0 eV, respectively, such that 2 eV is a reasonable estimate for the DDE of a (4sag)2 bond. Since the iron DDEs are ~40% stronger than this, the iron dimers appear to involve more than a simple (4$ 8)2 bond. They presumably must include extensive d-d bonding as well.Acknowledgment. This work is supported by the Army Research Office, DAAL03-87-2211, and a National Science Foundation Graduate Fellowship (D.A.H.). We thank Profs.Michael Morse and Jack Simons for several useful discussions.

Charge separation in 9,9?-dianthryl and a special pair treated by a semi-empirical reaction field method

“…However, the calculated dipole moment is too large and this may be due to the still missing final step [ 91 in our calculations as pointed out above. Although not conclusive on the amount of CT our results are consistent with hole-buring data [18][19][20][21][22]. The initial excited state already has a significant CT character immediately after excitation and this CT will increase as the permanent monopoles, dipoles and multipoles of the protein start to relax.…”

“…It has been argued on the basis of photochemical hole burning [18][19][20][21][22] and Stark effect experiments [23][24][25] that the special pair (P) in the reaction center of Rhodopseudonomas viridis has dipolar character in its S, state at 960 nm or alternatively that the S1 state rapidly (<lo0 fs) decays to or interacts with CT states [26- character in any of the lower excited states of the P dimer. Partly this was due to the strong interaction between the monomer units which resulted in MO evenly distributed over the two monomer units in P and partly to the omission of the reaction field.…”

Rapid-flow resonance Raman spectroscopy of bacterial photosynthetic reaction centers.

“…Resonance Raman data provide information that can be used in the quantitative interpretation of the extensive holeburning studies of the lowest energy absorption band of RCs (9)(10)(11)(12)(13)(14)(15)(16)(17). In the hole-burning experiments, a spectrally broad hole is observed, and with burn frequencies on the red edge of the P absorption band, a much narrower, extremely weak zero-phonon hole is seen.…”

“…After optical excitation, electron transfer from lP, the lowest-energy singlet excited electronic state of P, to a bacteriopheophytin acceptor occurs within about 3 ps at room temperature. Electroabsorption measurements suggest that 'P contains a large amount of charge-transfer character (4)(5)(6)(7)(8), and holeburning studies and theoretical models indicate that strong coupling exists between electronic and vibrational motions in P (9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). The electronic-nuclear coupling determines the nuclear motion that occurs after electronic excitation, but the description of this motion, including its role in possibly mediating the primary charge transfer, has been hampered by the lack of information about the vibrational modes of P that are coupled to optical excitation.…”

Sub‐picosecond dynamics of excited state of primary electron donor in reaction centers of Rhodopseudomonas viridis as revealed by hole burning at 1.7K broad and narrow holes

“…sphaeroides [2]. The same 150~cm -' vibronic mode has been revealed in the shape of the spectral hole burned within the P band [1,14,15,18,19].…”