arXiv subjects

P. O. J. Scherer

Publications and source records attributed to P. O. J. Scherer.

4 recordsLinked to original sources

arXiv2009

On the dimers of Pseudoisocyanine

The self organization of pseudoisocyanine-dimers in dilute aqueous solutions is studied by classical MD simulations. The electronic structure of the dimer is evaluated with the semiempirical ZINDO method to determine the fluctuations of site energies and excitonic coupling. We study different dimer conformations with blue or red shifted absorption maxima as models for H and J-aggregates. The width of the absorption bands is mainly explained by low frequency vibrations whereas the fluctuations of site energies are less important.

physics.chem-ph↗

arXiv2006

Quantum Chemical Analysis of the Excited State Dynamics of Hydrated Electrons

Quantum calculations are performed for an anion water cluster representing the first hydration shell of the solvated electron in solution. The absorption spectra from the ground state, the instant excited states and the relaxed excited states are calculated including CI-SD interactions. Analytic expressions for the nonadiabatic relaxation are presented. It is shown that the 50fs dynamics recently observed after s->p excitation is best accounted for if it is identified with the internal conversion, preceded by an adiabatic relaxation within the excited p state. In addition, transient absorptions found in the infrared are qualitatively reproduced by these calculations .

cond-mat.soft↗

arXiv1997

Charge separation in photosynthesis via a spin exchange coupling mechanism

A new mechanism for the primary photoinduced charge separation in photosynthesis is proposed. It involves as real intermediate between the excited special pair state P* and the primary charge separated state P+HL- a trip-trip-singlet PTBLT, which consists of a triplet on the dimer P and a further triplet on the monomer BL. Both combine to a singlet. The electron transfer is caused by spin exchange couplings. The transient spectrum of the short lived intermediate, formerly taken as evidence for the charge transfer state P+BL-, is reinterpreted as a transient excitation of this trip-trip singlet.

cond-mat.soft↗

arXiv1997

Interpretation of a low-lying excited state of the reaction center of Rb.sphaeroides as a double triplet

The recently observed transient absorption of the lowest excited state of the special pair P* at 2710 cm-1 is assigned as a singlet which arises from the coupling of the two lowest triplets from the two dimer halves. INDO calculations are used to predict its intensity. The analogy of the coupling mechanism to the trip-doublet spectrum from P+ is shown and the influence of the double triplet on the Stark effect of P* is investigated.

physics.chem-ph↗