Treatment of protonic delocalisation in water by the complex scaling method: theory and experimental results

Recently the complex scaling method has been extended to large systems (e.g. a liquid) by use of quantum statistics. The main tool for its extension is the theory of fermionic second-order density matrices as developed by Coleman. After proper treatment based on the complex scaling method the second-order density matrix reveals a new kind of off-diagonal long range order in the form of Jordan blocks. We call this kind of “order” coherent dissipative structures. To test the new theory, contact with experiment was sought and found in the form of protonic delocalisation effects in liquid H₂O. Two relations could be derived from first principles concerning (i) the limiting excess conductivity of mixtures of H⁺/D⁺ in H₂0/D₂0 and (ii) the proton exchange rate in the reaction H₂O+H₃O⁺ → H₃O⁺+H₂0 in relation to that in the reaction H₂0+OH⁻ → OH⁻+H₂O, which are in marked contrast to the results expected by conventional (i.e. classical) theories. The experiments have since been carried out and the theory was confirmed by both of them. Here we present briefly the theoretical predictions as well as the experimental results. Work on other fields (ionic conductance of molten alkali chlorides, the size of magnetic clusters in Gd far above the Curie temperature) illustrate that quantum interference or delocalisation effects (e.g. coherent dissipative structures) are important for the physics of condensed matter.     

Correlations and conductivity of interacting fermions in a disordered chain—a Monte Carlo simulation

The interplay between disorder and interaction in a one dimensional system of fermions is investigated by the use of a Monte Carlo simulation. The model considered (Hubbard Anderson Model) is a combination of the Anderson model, for noninteracting fermions in a random potential, and the extended Hubbard model, for interacting fermions in a periodic potential. To study the physics of this model, a (Quantum) Monte Carlo simulation is performed for a finite chain of 120 sites. The simulation is done for different band fillings, and several values of the interaction parameters and the strength of disorder. The low frequency behaviour of the conductivity is calculated as well as the static correlation functions for the charge density and the spin density. From the results for these quantities the competition between disorder-induced effects (Anderson localization) and interaction-induced effects (Mott transition, long range order) is studied.     

Transmission enhanced optical lenses with self-organized antireflective subwavelength structures for the UV range

We present transmission increased fused silica lenses produced by using self-organized antireflective structures for which we developed an efficient manufacturing process. The spectral transmission measured over the whole lens aperture shows a significant transmission enhancement of up to 3.5% in the UV range. Local measurements on the lens's surface reveal a strongly reduced reflection of below 0.1% for 300 nm wavelength, which is homogeneous over the whole lens. Further, the lenses show a broadband spectral antireflection behavior. For 600 nm wavelength the reflection was measured at about 1%.     

Ultrafast dynamics in thiophene investigated by femtosecond pump probe photoelectron spectroscopy and theory

A hybrid of a time-of-flight mass spectrometer and a time-of-flight "magnetic-bottle type" photoelectron (PE) spectrometer is used for fs pump-probe investigations of the excited state dynamics of thiophene. A resonant two-photon ionization spectrum of the onset of the excited states has been recorded with a tunable UV laser of 190 fs pulse width. With the pump laser set to the first intense transition we find by UV probe ionization first a small time shift of the maxima in the PE spectrum and then a fast decay to a low constant intensity level. The fitted time constants are 80+/-10 fs, and 25+/-10 fs, respectively. Theoretical calculations show that upon geometry relaxation the electronic state order changes and conical intersections between excited states exist. We use the vertical state order S1, S2, S3 to define the terms S1, S2, and S3 for the characterization of the electron configuration of these states. On the basis of our theoretical result we discuss the electronic state order in the UV spectra and identify in the photoelectron spectrum the origin of the first cation excited state D1. The fast excited state dynamics agrees best with a vibrational dynamics in the photo-excited S1 (80+/-10 fs) and an ultrafast decay via a conical intersection, presumably a ring opening to the S3 state (25+/-10 fs). The subsequently observed weak constant signal is taken as an indication, that in the gas phase the ring-closure to S0 is slower than 50 ps. An ultrafast equilibrium between S1 and S2 before ring opening is not supported by our data.     

Identification of post-translationally modified proteins in proteome studies.

Proteome studies are powerful tools to solve many different problems in metabolism, signal transduction, drug discovery, and other areas of interest in life sciences. Up to now, high-sensitive methods for protein identification after two-dimensional gel electrophoresis using mass spectrometry are available. However, the identification of post-translational modifications after two-dimensional gel electrophoresis is still an unsolved problem. In this paper, we want to give several examples for the successful identification of post-translational modifications and point mutations.     

An efficient route to the musk odorant (R,Z)-5-muscenone via base-metal-catalysis

Muscenone^® is a valuable perfume ingredient consisting of a mixture of the E- and Z-isomers of 1 in racemic form as the major constituents. Among them, it is the (R,Z)-isomer, which exhibits the most favorable musk character and by far the lowest threshold; for these superior olfactory properties, pure (R,Z)-1 has recently been commercialized too. We present an efficient route to this precious compound based on an iron-catalyzed cross coupling reaction, a molybdenum-catalyzed alkyne metathesis for the formation of the macrocyclic ring, and a nickel-catalyzed semi-hydrogenation.