Fraunhofer-Institut für Atmosphärische Umweltforschung IFU

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  • Patent
    Verfahren zur Ermittlung der Nitrifikations- und/oder Denitrifikationsrate von Boeden und Vorrichtung hierzu
    ( 2003)
    Butterbach-Bahl, K.
    DE 19906872 A UPAB: 20001023 NOVELTY - Determining soil nitrification and denitrification rates comprising introducing a soil sample into a gas- and pressure-tight vessel to leave a gas space above the soil, hermetically sealing the vessel, and measuring the pressure, and oxygen (O2) and carbon dioxide (CO2) concentrations at least at the start and end of an incubation period of 0.5-24 hours, is new. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for apparatus for carrying out the novel method, comprising a sealable gas-tight vessel having at least one pressure sensor access port and at least one sealable inlet. USE - For determining soil nitrification and denitrification rates using a complex set of equations given in the specification. ADVANTAGE - The method is simple and inexpensive.
  • Patent
    Vorrichtung zur Messung eines Spektrums
    ( 2003)
    Misslbeck, M.
    ;
    Seckmayer, G.
    ;
    Thiel, S.
    Es wird eine Vorrichtung zur Messung eines Spektrums einer Strahlung, insbesondere im UV-Bereich, vorgeschlagen, das einen Eingangsspalt, eine Anordnung zum Aufspalten der einfallenden Strahlung in ein Spektrum und Abbilden des Eingangsspaltes auf eine erste Fokalebene nach Wellenlaengen getrennt aufweist. Eine erste Empfaengeranordnung ist zeilenfoermig in der ersten Fokalebene vorgesehen und erfasst einen ersten Wellenlaengenbereich. Weiterhin ist der ersten Fokalebene eine Oeffnung und hinter der eine zweite Anordnung zum Aufspalten der durch die Oeffnung gelangenden Strahlung in ein zweites Spektrum und Abbilden der Oeffnung der ersten Fokalebene in eine zweite Fokalebene vorgesehen. Eine zweite Empfaengeranordnung in der zweiten Fokalebene erfasst somit einen zweiten Wellenlaengenbereich selektiv.
  • Patent
    Verfahren zur Herstellung von Isopren
    ( 1998)
    Zimmer, W.
    Production of isoprene comprises culturing a microorganism containing a plant isoprene synthase gene in a container at a temperature above 34 deg. C and capturing gaseous isoprene from the waste air. USE - Isoprene is used in the plastics and rubber industries; it is used to make isoprene rubber for the tyre industry; it is used to make butyl rubber for the manufacture of seals and hoses; it is used to make isoprenoids for use in the perfume industry.
  • Patent
    Interferometrisches Verfahren und Interferometer mit einem Diodenlaser
    ( 1997)
    Werle, P.
    Using the process according to the invention and the arrangement for absolute interferometry specified for performing the process using radiation generated by diode lasers, relative or absolute distance measurements can be performed without reference interferometers using only one detector and with high precision of the test section measurement. The basic idea of the invention is to modulate radiation generated by a diode laser in such a way that at least a discrete frequency is imposed on the diode laser, said frequency being detected using a known phase-sensitive detection process. As a result of modulating the original radiation of the diode laser, a second laser beam is more or less generated so that a measuring and a reference beam result in a single beam path. The two beams, i.e. the measuring and the reference beam, each have a different frequency, but have parallel wave fronts, travel precisely along the same optical path in the uniform beam path and interfere on the single det ector. The test section is then determined by the above mentioned detection of the phase shift and the detection of the phase shift in the modulation signal. Alternatively, the modulation frequency of the diode laser is changed until a specified phase shift between the original first beam of the diode laser and the second beam generated by modulation is detected by the detector ...
  • Patent
    Verfahren und Anordnung zur Driftkorrektur zeitdiskreter Messsignale bezogen auf ein Referenzsignal, insbesondere in der absorptionsspektroskopischen Spurengasanalytik
    ( 1997)
    Werle, P.
    The invention relates to a process and a setup for correcting the drift of time-discrete measuring signals referred to a reference signal, in particular for use in absorption-spectroscopic trace gas analysis. By means of the invention, the accuracy of measuring signals obtained from a large number of spectra and scans can be increased. An on-line drift correction is provided for this, and can be used in particular for spectroscopy using semiconductor diode lasers, as well as all other measuring processes in which signal drift results in an impairment of the test result. Due to the fact that on-line analysis and correction of the relative shift between the measuring and calibration spectra and the reference signal is performed before the data are summarized by means of averaging, the otherwise necessary storage of large numbers of unprocessed spectra for later off-line analysis can be avoided. The on-line drift correction process according to the invention can be implemented by using on ly hardware or only software as well as by means of a combination of hardware and software.
  • Patent
    Verfahren und Anordnung zur abwechselnden Proben- und Untergrundmessung, insbesondere bei der hochempfindlichen absorptionsspektroskopischen, selektiven Spurengasanalyse
    ( 1997)
    Werle, P.
    The invention relates to a process and an arrangement for alternating test and background measurement, in particular for highly sensitive absorption spectroscopy selective gas analysis. Instead of a previously usual exchange of sample air or sample gas in a measuring cell to receive a sample-free zero air, the invention foresees applying a magnetic and/or electrical field to the trace or test gas in the measuring cell for a predetermined period of time. As a result of the effect of the field, a shift in the energy level of the gas molecules takes place in the measuring cell acc. to the strong or Zeeman effect. Sensitivity-limiting background structures are not influenced by the field effect. In a viewed measuring window, sample and background measurements can then be performed in succession without any time delay by cyclically alternating the activation and deactivation of the field. By not physically replacing the gas in the measuring cell, as previously was the case, but shifting the position of the characteristic spectral signatures for the species under investigation, the background structure can be determined in the temporal signal-free spectral measuring window in the usual way. As a result of the invention, drift effects of the absorption-spectroscopy measuring instrument can be reduced, whereby at the same time an increase in measuring sensitivity can be obtained.
  • Patent
    Verfahren und Vorrichtung zur Bestimmung der Emissionsrate mindestens einer Gaskomponente eines Gasgemischs
    ( 1996)
    Rippel, H.
    ;
    Schaefer, K.
    The process according to the invention and the device for the calculation of the emission rate (Ns) of a gas component (G1, G2) in a gas mixture (G) consists of an intensity measuring instrument (GSC) for the selective measurement of the spatial intensity distribution (Is(x, y)) of at least one gas component (G1, G2) of the gas mixture (G). A particle analyzer (TAN) is provided for the measurement of the length-integrated particle volume ((n x L)s) of at least one gas component (G1, G2) along the width (L) of the gas flow (G). A first calculation instrument (C1) determines from the spatial intensity distribution (Is(x, y) the flow velocity (v) of the gas mixture (G), a second calculation instrument (C2) determines a geometry factor (G) for the gas component from the gradient of the spatial intensity distribution (Is(x, y) in the radial direction (x) and a third calculation instrument (C3) determines the emission rate (Ns) from the ge ometry factor (G), the flow velocity (V) and the len gth-integrated particle volume ((n x L)s). Through the use of the device and the process, not only the spatial distribution of at least one gas component (G1, G2) in a gas mixture can be evaluated but also dynamic processes.
  • Patent
    Verfahren und Anordnung zur Bestimmung und Normierung der Intensitaet eines Messsignals, insbesondere bei der Modulations-Laser-Absorptionsspektroskopie
    ( 1995)
    Werle, P.
    The invention relates to a process and an arrangement which helps to perform a determination and normalization of the intensity of a measuring signal, in particular for modulation absorption spectroscopy or interferometry, whereby only a single measuring detector is required and no otherwise necessary reference channel is required. By means of on-line normalization and the use of a frequency modulation method, a diode laser is modulated in such a way that at least one discrete frequency is superimposed on the former. The frequency-modulated laser radiation at its original intensity is then subjected to an intensity attenuation in an absorption measuring cell, said attenuation being determined by means of a phase-sensitive detector. According to the invention, a residual amplitude of the modulation signal is determined at the output of a single detector, whereby said residual amplitude represents a measure of the original intensity. The residual amplitude value can then be used for know n intensity normalization methods.
  • Patent
    Verfahren und Anordnung zur Stromversorgung eines Messlasers, insbesondere eines Diodenlasers zur absorptionsspektroskopischen Spurengasanalytik
    ( 1994)
    Werle, P.
    The invention relates to a process and a setup for the power supply of a measurement laser, in particular a diode laser for absorption-spectroscopic trace gas analysis. According to the invention, a diode laser power supply output stage with an extremely low bandwidth is used, whereby there is full electrical isolation between the direct-current diode laser power supply and a tuning signal implemented in the diode laser using optical means. Faults, which otherwise access the diode laser via the power supply, are suppressed efficiently by means of the low bandwidth of the laser power supply, which no longer depends on the frequency of the signal required for tuning; this permits stable operation of the laser and this is the basis for high sensitivity in the measuring system equipped accordingly. To prevent a phase shift between the optical signal for tuning the diode laser and the resulting frequency change in this signal, a thermal-optical projection and the supply of a defined quantit y of heat emanating from the tuning laser take place directly in the region of the pn transition between the measurement and diode lasers.
  • Patent
    Anordnung zum Bewerten eines Messsignals nach Betrag und Phase in Bezug auf ein Referenzsignal
    ( 1994)
    Werle, P.
    The invention relates to a setup for evaluating a measuring signal for its amount and phase in relation to a reference signal and is used preferably in optical spectroscopy for building a measurement setup for trace gas analysis using modulated laser radiation, e.g., that of a diode laser. The invention proposes the simultaneous operation of single-tone and double-tone systems for modulating and demodulating the signal of the diode laser, whereby evaluation of the measuring signal is simplified. The main feature here is that a decision can be made a priori as to which modulation or demodulation process can be given preference. As a result of the flexibility of the solution proposed by the invention, it is possible to select an optimum technology suited to the given conditions. Since all components can be designed to be computer-controlled, computer-controlled optimization is possible. As a result of the invention, high modulation frequencies are achievable and it can be applied in rapi d-tuning cw systems and in pulsed laser spectroscopy systems. By reducing interfering harmonics in the modulation signal and as a result of the interference-free reference signal, the signal-to-noise ratio of the actual measuring signal is increased. Moreover, a high time resolution of the measuring signals can be achieved and, as a result of modular design and signal and connection compatibility with known design forms, old waste sites can be cost-effectively...