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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 3430-3439 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A time-resolved spectral photometer, i.e., an instrument for simultaneously measuring intensity, time, and wavelength (I-t-λ) is described. The "spectro-streak'' apparatus comprises a grating objective coupled to a commercial streak camera with 2-ps resolution, a channel plate amplifier, a CCD camera, and a computer for data processing. The necessary calibration and correction procedures are discussed in detail; these are sweep nonlinearity correction, shading correction, geometric distortion correction, wavelength calibration, spectral intensity correction, and dispersion correction. The performance of the instrument is demonstrated with an example of current interest, the measurement of the solvatochromic dynamic Stokes shift of fluorescence from a charge-transfer system in solution.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 3790-3798 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We designed and built a combination of a scanning tunneling microscope (STM) and a scanning electron microscope (SEM) which is working under ultrahigh vacuum conditions (base pressure typically 7⋅10−11 mbar). The SEM is ideally used for surveying the sample and to control the STM tip positioning, while the STM extends the resolution range into the atomic scale. The design concept allows moving the STM tip freely over the sample under SEM control and using both imaging techniques simultaneously. The system is equipped with an electron energy analyzer (cylindrical sector analyzer) providing Auger electron spectroscopy, scanning Auger microscopy (SAM) and x-ray photoelectron spectroscopy capabilities. In addition, low energy electron diffraction and reflection high energy electron diffraction facilities are installed. In order to use these very different imaging techniques in situ, several special solutions had to be incorporated in the design of the system; they are described in detail. Some results are presented which demonstrate the performance of the STM/SEM system. Atomic resolution of the STM, a SEM resolution of up to 20 nm, and a SAM resolution of better than 100 nm were achieved. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 2490-2495 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Results of a pilot study with a spectro-streak apparatus applying a grating microspectrometer with a self-focusing reflection grating are reported. The microspectrometer chip (dimensions: 17×6.4 mm2; 125 μm effective thickness of the three-layer x-ray resist system), fabricated with the versatile LIGA technique, has been adapted to a picosecond streak camera. Performance tests have been carried out with a fluorescent probe exhibiting a dynamic Stokes shift of the exciplex fluorescence band due to solvation of the charge transfer dipole within about 400 ps. The use of a LIGA microspectrometer in ultrafast spectroscopy proved to be of advantage in time-resolved studies of complex luminescence spectra where a moderate spectral resolution is required and a large spectral range must be covered. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 99 (1995), S. 14923-14930 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 45 (1996), S. 692-699 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Investigations into aerobic biological degrada-tion were carried out as part of an extensive programme designed to facilitate the cheap remediation of a pyrolysis waste-water deposit. Attention was focused on the processes of carbon conversion by different populations. The susceptibility of a body of lignite-processing deposit water to microbiological degradation was examined in batch investigations in a Sapromat system and in continuous bench-scale fermenter cultivations, with respect to nutrient supply, inoculation culture and molecular size distribution. It was found that degradation best occurs with an adapted mixed culture. The autochthonous culture removes 30% less dissolved organic carbon (DOC) and has a 40% higher specific oxygen demand. A shortage of phosphorus, investigated with a view to avoiding additional eutrophication problems in the open water in the case of in situ remediation, causes reduced DOC degrada-tion and significantly higher specific oxygen demand. The biological process is overlapped by abiotic oxidation. During aerobic treatment, a concentration of colour-giving aromatic substances of between 0.5 kDa and 5 kDa was observed. This phenomenon is caused by the oxidation of low- and high-molecular-mass compounds. The removal of DOC is limited to 65% and mainly occurs in the range below 0.5 kDa (30%) and in the 0.5–1 kDa range (12%); the removal is negligible in the ranges 1–3 kDa (0.8%) and 3–5 kDa (2%) and a little higher in the ranges 5 kDa–0.3 μm (5%) and above 0.3 μm (6%). In the investigations it was discovered that DOC removal causes in the ranges below 0.5 kDa, 0.5–1 kDa and 5 kDa–0.3 μm mainly as a result of degradation, but the range above 0.3 μm is chiefly caused by bioadsorption. Aerobic microbiological treatment is able to remove most low-molecular-mass substances. In order to remove the macromolecular and colour-giving part of the deposit water, an additional treatment stage, e.g. flocculation, is required.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of fluorescence 4 (1994), S. 87-90 
    ISSN: 1573-4994
    Keywords: Spectro-streak photometer ; picosecond excitation ; intramolecular charge transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A spectro-streak photometer, an instrument for simultaneously measuring fluorescence intensity, time, and wavelength,I(t, λ), with a single picosecond excitation pulse, has been constructed. Two typical and currently highly topical examples of mesurements are discussed. (1) the temporal development of the fluorescence form the intramolecular charge-transfer (ICT) state of the rigid aromatic compound 4,5-(1′-methylindolino)3,4-naphthanthracene is studied in the protic solvent hexanol. (2) Propyl chain-linked pyrene/N,N-dimethylaniline is used as the model compound to study conformational changes associated with the transition from a contact ion pair to a sandwich exciplex.
    Type of Medium: Electronic Resource
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