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Notes: By means of laser deposition, spin casting and vacuum evaporation, optoelectronic hybrid devices were manufactured based upon the thin-film heteropairing of a perylene-derived molecule [di-isoquinoline perylene derivative (DQP)] and CdS. The photovoltaic characteristics of the devices are presented and discussed. We demonstrate that by exploitation of relatively high carrier mobilities in the CdS layer and the high photonic yield and deposition ease of the DQP film, efficient and technologically appealing optoelectronic devices are feasible. In addition, bias dependence of the spectral sensitivity demonstrates the versatility of the introduced device concept in light of photonic sensor applications. © 2002 American Institute of Physics.

Notes: The photoluminescence of oriented thin-film CdS on glass formed by laser deposition was investigated employing 200 fs, 1.54 eV laser pulses at room temperature. The ultrafast excitation caused a two-photon absorption process, which results in purely green emission at the band gap. The spectra are fitted very well by the application of the van Roosbroeck–Shockley relation, density of states, and Urbach's rule demonstrating the intrinsic character of the radiative recombination. It is further shown that the energy position of the emission peak depends on the polarization of the impinging laser beam due to the dichroism of the highly oriented films. © 2002 American Institute of Physics.

Notes: The (3)/(2) ω0 harmonic emission has been observed from a laser-produced plasma using exploding foil targets illuminated by 1.053 μm laser light with a 300 psec square pulse. The shift of the measured wavelength from (2)/(3) λ0 is found to depend markedly on the target thickness. Variation of the flow velocity and thus the Doppler shifts of the wave frequency with target thickness is found to be more important than variation of the electron temperature. Adjusting the measured wavelength by Doppler shifts calculated with flow velocities from simulations brings the measurements from different target thicknesses into agreement. These results indicate that previous predictions of electron temperatures from analyses of half-harmonic spectra from inertial confinement fusion plasmas are up to a factor of 2 too small.

Notes: Intrachain exciton quenching in ladder-type polyparaphenylene has been quantified for the first time. Two-phonon absorption and subsequent upconverted photoluminescence of ladder-type polyparaphenylene and polyfluorene has been measured and analyzed with a new theoretical framework for the two-photon absorption saturation. This microscopic analysis determines the number of singlet excitons as a function of the excitation intensity, which is compared to the photoluminescence intensity. The absorption saturation alone perfectly describes the photoluminescence saturation in polyfluorene, whereas in ladder-type polyparaphenylene, exciton–exciton quenching occurs. By measuring in solution, the formation of stacked polymer chains is prevented. Therefore, the quenching is due to intrachain interaction. © 2002 American Institute of Physics.

Notes: Gold disk targets were irradiated with green (λ=0.53 μm) laser light at intensities between 0.5 and 5×1014 W/cm2 using shaped laser pulses. Plasma conditions near and below critical density (nc(approximately-equal-to)4×1021/cm3) were determined from three diagnostics. Streaked one-dimensional images of the M-band emission (2–3.5 keV) along the laser axis yield the peak emission trajectory. Temporally and spatially averaged measurements of the hard x-ray spectrum (4–25 keV) were used to determine the average coronal electron temperature. Holographic interferometry was used to determine the electron density profiles and scale lengths along the laser axis. The peak emission trajectory, electron temperature, and scale lengths are all in good agreement with simulations, but the magnitudes of the electron density profiles are not, as discussed in an accompanying paper [Phys. Fluids B 2, 2448 (1990)].

Notes: Stimulated Raman scattering (SRS) was studied in experiments with laser-irradiated Au disk targets. Typically the laser energy was 150 J in a 1.0 nsec pulse at a wavelength of 526 nm. Laser intensity at the target was ∼7×1014 W/cm2. The spectrum, angular distribution, onset time, duration, and intensity of the Raman light were measured. In addition the electron density distribution was determined by holographic interferometry and images of the Raman emission were obtained. These data show that the Raman light is primarily backscattered and that scattering occurs at electron plasma densities 0.01 nc ≤n≤0.15nc. SRS occurred at laser intensities which are below theoretical thresholds, given the plasma conditions. Otherwise, most of the data support the present understanding of Raman scattering.

Notes: These experiments investigate events involved in triggering sugar accumulation in the cold in tubers of Solanum tuberosum L. cv. Desirée. Sugar content, 14C-glucose metabolism, metabolite levels and activities of sucrose phosphate synthase (SPS) and starch-degrading enzymes were followed after transfer to 4°C. (i) Net sucrose accumulation began between 2 and 4 d. By 10 d, reducing sugars were also increasing. From 20 d onwards, sugar accumulation slowed. Sucrose fell, but reducing sugars continued to increase. (ii) To measure unidirectional sucrose synthesis, U-[14C]glucose was injected into tubers after various times at 4°C. The tubers were then incubated for 6 h. After 1 d at 4°C, both the absolute and the relative (expressed as a percentage of the metabolized label) rates of sucrose synthesis decreased compared to those at 20°C. Between 2 and 4 d at 4°C, labelling of sucrose increased 3-fold, to over 60% of the metabolized label. This high rate was maintained for up to 50 d in cold storage. When tissue slices were incubated with 2.5 mol m−3 U-[14C]glucose, the rate of labelling of sucrose in slices from 6 d cold-stored material was higher than in slices from warm-stored material, irrespective of whether the incubation occurred at 4°C or at 20°C. (iii) Hexose-phosphates increased during the first day after transfer to 4°C. Their levels fell during the next 3 d, as sucrose synthesis increased. They then rose (until 20 d) and fell, in parallel with the rise and decline of sucrose levels. UDPglucose remained unaltered during the first 4 d, and then increased and decreased in parallel with sucrose. (iv) SPS activity assayed in optimal conditions and the total amount of SPS protein did not change. However, when assayed in the presence of phosphate and limiting substrate concentrations, activity rose 3–5-fold between 2 and 4 d. (v) Amylases and phosphorylases were investigated using zymograms to separate isoforms. Phosphorylases did not change. Between 2 and 4 d at 4°C, a new amylolytic activity appeared. (vi) Estimates of the specific activity of the phosphorylated intermediates and the absolute rate of sucrose synthesis (calculated from the 14C-labelling data and metabolite analysis) showed that changed kinetic properties of SPS and decreased levels of hexose-phosphate are accompanied by a 6–8-fold stimulation of sucrose synthesis. They also show that the final level of sugar is partly determined by a cycle of sugar synthesis and degradation. (vii) It is concluded that the onset of sugar accumulation in cold-stored tubers is initiated by a change in the kinetic properties of SPS and the appearance of a new amylolytic activity. It is discussed how other factors, including hexose-phosphate levels and subcellular compartmentalization, could also influence the final levels of sugars by altering the balance of sugar synthesis and remobilization.