2CLabManual201303

Light source wavelength selector sample figure 2

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Unformatted text preview: a reflection grating with associated optics) to select a narrow range of wavelengths, and a photoelectric detector to measure the light intensity, as indicated in Figure 2. Light Source |ℓ | Wavelength Selector Sample Figure 2: Schematic Representation of a Spectrophotometer. In addition to identifying a substance, an absorption spectrum can be used to determine its concentration because the absorbance, the amount of light of a given wavelength absorbed by a substance, is proportional to the number of molecules present in the sample. This relationship is called the Beer-Lambert Law or more simply Beer’s Law. Consider monochromatic light of a given intensity incident on a sample, as shown in Figure 2. If this light can be absorbed by the sample, then the transmitted light will have a lower intensity than the incident light. The transmittance, T, is defined as the ratio of the transmitted intensity, I, to the incident intensity, I0, T I I0 The percent, %T, is simply 100 T. The transmittance is decreased if either the concentr...
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This note was uploaded on 04/09/2013 for the course CHE CHE 2C taught by Professor Nasiri during the Spring '07 term at UC Davis.

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