@article{EngelhardLoehmannsroebenSchael2004,
  author    = {Engelhard, Sonja and L{\"o}hmannsr{\"o}ben, Hans-Gerd and Schael, Frank},
  title     = {Quantifying ethanol content of beer using interpretive near-infrared spectroscopy},
  issn      = {0003-7028},
  year      = {2004},
  abstract  = {On the basis of absorption measurements in the near-infrared (NIR) spectral range, a new method for the quantification of the ethanol content of beer is presented. Instead of the multivariate calibration models most commonly employed in NIR spectroscopic works, we use interpretive difference spectroscopy: Two wavelengths are selected according to the assignment of the absorption bands of the main substances of content of beer in the NIR region, and the difference between the absorbances at these wavelengths is used for ethanol quantification. Absorption spectra of the dominating beer ingredients are discussed and the calibration procedure with ethanol/water mixtures is shown. Robustness against the carbohydrate content of beer samples was demonstrated by analyzing solutions of ethanol and maltose in water. Validation of the method was performed with various beer samples with an ethanol concentration range between 0.5 and 7.7 vol \%. The pertinent advantage of the procedure developed in this work is the indication that the results are independent from seasonal variations of the ingredients, which is of high interest for products with natural ingredients such as beer},
  language  = {en}
}
@article{SchaelReichLoehmannsroeben2000,
  author    = {Schael, Frank and Reich, Oliver and L{\"o}hmannsr{\"o}ben, Hans-Gerd},
  title     = {Near infrared diode laser spectroscopy of organic compounds in turbid aqueous solutions},
  isbn      = {0-9528666-1-7},
  year      = {2000},
  abstract  = {Diffuse reflectance measurements and photon migration studies with near infrared (NIR) diode lasers were employed to elucidate experimental methods for determining absorption and scattering coefficients and species concentrations in highly scattering solutions. Applicability of theoretical approaches were established by investigating model systems with absorbing (e.g. ink, malachite green) and scattering (e.g. milk powder, caolinit) species in aqueous solution. While diffuse reflectance measurements practically requires calibration procedures, photon migration studies allow quantitative determination of absorption and scattering coefficients of turbid solutions consistent with absorptions coefficients obtained from Lambert-Beer's law. Furthermore, NIR absorption spectra of water, chlorinated hydrocarbons (chloroform, 1,2-dichloroethane, trichloroethene) and of various sugars (\$alpha\$-D-glucose, sucrose, maltose) are discussed. Spectral variations of NIR water absorption with temperature and solvents are exammined. Exemplary, NIR diode laser detection of water in acetone/water mixtures is performed.},
  language  = {en}
}
@article{SchaelReich2001,
  author    = {Schael, Frank and Reich, Oliver},
  title     = {In-situ-Analytik heterogener Medien mit frequenz- und leistungsmodulierten Diodenlasern},
  year      = {2001},
  abstract  = {Electronic intensity and frequency modulation of diode lasers enables new perspectives for highly sensitive analytical in-situ techniques. For analyis of "heterogeneous" media, which may consist of coexisting gaseous, liquid, and solid phases and often show multiple light scattering, non-invasive techniques with outstanding performance characteristics can be developed. Analysis of photon density waves launched by intensity-modulated lasers provide an elegant way for the determination of absorption and scattering coefficients of multiple scattering media. The absorption coefficient can be used for qualitative and quantitative analysis of chemical constituents (which absorb in the range of the laser wavelengths). The scattering coefficient allows characterization of physical and morphological properties of the sample. In the current work, applicability of appropriate radiation transport models was investigated with simple light scattering solutions and compared with results obtained from the treatment according to the theory of Kubelka and Munk. Measurements of human blood samples are discussed. A new method for determination of water vapor partial pressure in a polyurethane foam with a frequency-modulated external cavity diode laser is discussed.},
  language  = {de}
}
@article{LoehmannsroebenSchaelReichetal.2000,
  author    = {L{\"o}hmannsr{\"o}ben, Hans-Gerd and Schael, Frank and Reich, Oliver and Lemke, Matthias and Schober, Lars},
  title     = {Untersuchung von organischer Bodensubstanz und Bodengasen mit laser-spektroskopischer in-situ Meßtechnik},
  year      = {2000},
  language  = {de}
}
@article{SchaelEngelhardReich2001,
  author    = {Schael, Frank and Engelhard, Sonja and Reich, Oliver},
  title     = {Optische Sensorik f{\"u}r die in-situ-Analytik von Brauprozessen},
  year      = {2001},
  language  = {de}
}