Spectroscopy

Measures absorption and scattering Spectrometer for turbid media

The new SphereSpectro 150H spectrometer system from Gigahertz-Optik offers a solution for simultaneously determining the spectral absorption and scattering coefficients for scattering samples. Conventional spectrophotometers (also called transmission spectrometers or absorption spectrometers) are used to determine the absorption coefficient of clear or colored media. In a similar way to these conventional systems, the SphereSpectro 150H is used to determine the spectral absorption coefficient of scattering media.

To do this, the sample is illuminated and the transmitted as well as the reflected light is measured and evaluated in a differentiated manner using radiative transfer theory. For clear samples the absorption coefficient is determined based on Beer-Lambert's law. However, if the sample exhibits scattering (turbid or translucent samples), the entire physical process must be considered, that means a combination of scattering and absorption properties.

The spectrometer can determine the absolute absorption coefficient for scattering media independent of the scattering properties of the turbid medium. At the same time, the effective scattering coefficient of the sample is determined, which provides additional information about the microstructure of the sample.

According to the manufacturer, this is a unique feature which is not otherwise available on the market.

The determined absorption coefficient is identical with the conventional one for clear media and can be used for content determinations, for example. The spectrometer uses an integrating sphere to measure the total reflected and transmitted light of an illuminated sample. From these two quantities, the absorption coefficient and the effective scattering coefficient are calculated based on the radiative transfer equation.

The system covers the wavelength range between 200 nm and 2150 nm. Modular versions are also available for sub-ranges within this entire spectral range. According to the manufacturer, the measuring system is also characterized by simple operation, short measurement times and a large sample chamber with optimized sample holder whilst keeping overall size to a minimum.

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www.gigahertz-optik.com

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