Delta NANOTRACE DF-745 Instruction Manual download pdf (Page 81)

Theory of Operation DF-745 77

10 Theory of Operation

10.1The Moisture Measurement

10.1.1 Moisture and the IR Spectrum

Figure 84: Schematic of Moisture Cell

The Nanotrace Moisture analyzer uses infrared (IR) absorption as its detection method. IR

absorption is but a subset of the overall field of “spectroscopy,” which measures the

interaction of light and matter.

The basis of absorption spectroscopy is when an electromagnetic wave (i.e., the scientific

description of “light”) with a particular wavelength impinges on a substance that absorbs a

fraction of the total electromagnetic radiation. The wavelength of radiation is well known,

for instance, in differentiating colors in the visible light spectrum.

In the infrared spectral region, the wavelength of light overlaps with discrete absorptions

created by molecular vibrations. IR absorption is often used in diagnosing molecular

composition based on “fingerprints” of these absorptions over a wide wavelength range.

Conversely, if the strength of a single vibrational absorbance is known, a single wavelength

is often used to determine the amount of a particular substance. This is how we measure

moisture.

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Delta NANOTRACE DF-745 Instruction Manual Page 81