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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 116 (2002), S. 3316-3322 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Sulfur 1s excitation of S2 and S8 is reported. The experiments made use of monochromatic synchrotron radiation from the BW-1 beam line at the HASYLAB (Hamburg, Germany), where total cation yields and photoionization mass spectra were investigated as a function of the source temperature that was used for evaporation of α-sulfur. The near-edge structure undergoes characteristic changes as a function of the source temperature, reflecting significant size- and geometry-dependent changes in electronic structure of the sulfur clusters. The detailed analysis of the near-edge features is obtained from ab initio (MR-SDCI) calculations that focus on S8 and S2. The present results are discussed in comparison to previous work on inner-shell excited sulfur clusters as well as condensed sulfur. The near-edge structure of S2 is compared to that of O2 and Se2, yielding characteristic differences in core–valence and valence–valence–exchange interaction. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology ecology 19 (1996), S. 0 
    ISSN: 1574-6941
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract: The retentostat was developed for long-term continuous, axenic cultivation of microorganisms at those low growth rates which prevail in most natural habitats and which cannot be established properly in chemostats. How a microbial population approaches ‘zero-growth’ was studied in axenic cultures of Nitrosomonas europaea with complete biomass retention at 25°C and constant input of a nutrient solution containing ammonium (0.57 mM) as energy source. Since only cell-free filtrate left the reactor, biomass accumulated until a stable maximum of 2.7 × 109 cells ml−1 (398 mg l−1 dry matter) was reached after about 5 weeks. In this state, growth rate approached zero, and the ammonium input just met the substrate demand required for maintenance energy (1.43 μmol NH3–N mg dm−1 h−1). The potential of the retentostat for studying interactions between different microorganisms was demonstrated with a cascade of cultures of Nitrosomonas, Nitrobacter, and a denitrifying Pseudomonas. Thereby the ammonia was completely eliminated from artificial wastewater.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chester : International Union of Crystallography (IUCr)
    Journal of synchrotron radiation 8 (2001), S. 154-157 
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Recent progress on core-level excitation of molecular van der Waals clusters is reported. Resonant excitation near element K edges of isolated and clustered molecules gives rise to small spectral shifts that can only be detected with high spectral resolution. This requires the use of state-of-the-art storage-ring facilities along with insertion devices and high-resolution soft X-ray monochromators. Selected experimental results on carbon monoxide clusters are reported. For the vibrationally resolved C 1s → π* (v = 0) band of clustered CO, these indicate characteristic line broadening as well as a small red shift of 2 ± 1 meV compared with the isolated molecule. The results are discussed within the framework of the quasi-atomic approach with respect to intermolecular interactions, freezing of molecular rotations in clusters, and dynamic localization of resonant core-to-valence excitations.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 198 (1963), S. 13-20 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary 1. For high frequency plasma flames generators of various types are used for the frequencies 27.1, 461 and 2,400 Mcps. 2. The high frequency plasma flame is suitable for the exitation of materials, which get into the flame as small fluid particles. 3. The background essentially consists of lines and bands of the working gas and the solvent. 4. The intensity of a spectral line has a fluctuation of about 3–4 pc. 5. The sensitivity limit for a list of elements is reported. 6. Elements with a low ionisation potential produce notable interactions in the plasma, while elements with high ionisation potential show no interferences. 7. With air as working gas measurements of temperature indicate 3,000–4,000°K according to the height in the flame.
    Notes: Zusammenfassung 1. Zur Erzeugung von hochfrequenten Plasmaflammen wurden Generatoren verschiedener Bauart für die Frequenzen 27,1, 461 und 2400 MHz verwandt. 2. Die hochfrequente Plasmaflamme ist geeignet zur Anregung von Stoffen, die als Aerosol dem Arbeitsgas zugesetzt werden und als Flüssigkeitsnebel in die Flamme gelangen. 3. Als Untergrund stören wesentlich nur die Linien und Banden des Arbeitsgases und des Lösungsmittels. 4. Die zeitlichen Intensitätsschwankungen einer Spektrallinie betragen etwa 3–4%. 5. Eine Reihe von Elementen läßt sich mit guter Grenzempfindlichkeit nachweisen. 6. Die Wechselwirkungseffekte im Plasma werden hauptsächlich durch Elemente mit niedriger Ionisierungsspannung hervorgerufen, während Elemente mit hoher Ionisierungsspannung keinen Einfluß zeigen. 7. Temperaturbestimmungen in Luft als Arbeitsgas ergeben je nach Flammenhöhe Temperaturen von 3000–4000°K.
    Type of Medium: Electronic Resource
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