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Phthalocyanines in combination with C60 are benchmark materials for organic solar cells. Here, we have studied the morphology and electronic properties of co-deposited mixtures (blends) of these materials forming a bulk heterojunction as a function of the concentration of the two constituents. For a concentration of 1:1 of Cu-Phthalocyanine (CuPc):C60, a phase separation into about 100 nm size domains is observed, which results in electronic properties similar to layered systems. For low C60 concentrations (10:1 CuPc:C60), the morphology, as indicated by Low-Energy Electron Microscopy images, suggests a growth mode characterized by (amorphous) domains of CuPC, whereby the domain boundaries are decorated with C60. Despite of these markedly different growth modes, the electronic properties of the heterojunction films are essentially unchanged. [ABSTRACT FROM AUTHOR]

Selective optimization of the 39,39K2 and 39,41K2 isotopomers in a three-photon ionization process is presented by applying evolution strategies on shaped fs pulses in a feedback loop. The optimizations at different center wavelengths show considerably large enhancements of one isotope compared to the other and reversed. We compare the acquired optimized pulse shapes for combined phase and amplitude with pure amplitude modulation. Particularly from their spectra we are able to extract information about the optimally chosen differing ionization paths via the involved vibrational states. Furthermore, a comparison of the temporal shape of the optimized pulse forms for combined phase and amplitude with pure phase optimization is given. The presented pulse form analysis demonstrates the potential of restricted optimization to gain insight into the underlying dynamical processes. Our approach reveals how the optimization algorithm precisely addresses the vibrational wave functions both spectrally and temporally.© 2005 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The optimal control theory and closed-loop learning technique, which maximizes the ionization yield of NaK is used to shape the tailored laser pulses. The results show that the optimal control not only serves for maximizing the desired yield but also as a tool for the analysis and the identification of the responsible process.

Abstract: Photoelectron–Auger electron coincidence spectroscopy is a powerful tool for the investigation of Auger decay processes with different core-ionized intermediate states. In this paper we describe an investigation into the Auger decay of the O2 molecule, with the purpose of bringing new insight into the dynamics of the core hole decay mechanism. Using a novel experimental approach to measuring such coincidence spectra we report the highest resolution Auger spectrum of O2 recorded hitherto. In our approach, we have combined the advantages of these coincidence spectra with the high resolution and excellent signal-to-noise ratios of non-coincident Auger spectra and a state-of-the-art fit analysis. In this way we have derived information about the potential energy curves of the final states W 3Δu, B 3Πg, and B′3Σu − and concluded that the corresponding Auger transitions are formed to a large part by strongly overlapping vibrational progressions. The present findings are compared to earlier results reported in the literature confirming some theoretical predictions. [Copyright &y& Elsevier]

Selective optimization of different isotopomers in an ionization process with shaped fs-laser pulses is presented for 23Na39K/23Na41K. By employing evolution strategies in a closed feedback loop a considerably high enhancement by a total factor of about 25 of one isotope compared to the other and reversed is measured. Surprisingly, vibrational levels of differing electronic states are utilized for the different isotopomer selections. Our approach generally allows to influence vibrational wave functions by coherent interaction with the corresponding spectral pulse components on the fs-time scale. [Copyright &y& Elsevier]

Monochromatic radiation with known absolute radiant power from an undulator at the electron storage ring Metrology Light Source (MLS) was used to irradiate PTB7 (a thieno[3, 4-b]thiophene-alt-benzodithiophene polymer) thin films at wavelengths (photon energies) of 185 nm (6.70 eV), 220 nm (5.64 eV), 300 nm (4.13 eV), 320 nm (3.88 eV), 356 nm (3.48 eV) and 675 nm (1.84 eV) under ultra-high vacuum conditions for the investigation of radiation-induced degradation effects. The characterization of the thin films is focused at ultraviolet photoelectron spectroscopy (UPS) of valence bands and is complemented by S 2p x-ray photoelectron spectroscopy (S 2p XPS) before and after the irradiation procedure. The radiant exposure was determined for each irradiation by means of photodiodes traceably calibrated to the international system of units SI. The valence band spectra show the strongest changes for the shortest wavelengths and no degradation effect at 356 nm and 675 nm even with the highest radiant exposure applied. In the spectral range where the Sun appears bright on the Earth's surface, no degradation effects are observed.