Ocean Optics HR2000CG-UV-NIR - Manual (Page 24)

Sample Experiments
HR2000 High-Resolution Fiber Optic Spectrometer 20
Absorbance Experiments
Absorbance spectra are a measure of how much light a sample absorbs. For most samples, absorbance is
linearly related to the concentration of the substance. OOIBase32 calculates absorbance (A
λ
) using the following
equation…
S
λ
- D
λ
A
λ
= - log
10
(
R
λ
- D
λ
)
…where S
λ
is the sample intensity at wavelength λ, D
λ
is the dark intensity at wavelength λ, R
λ
is the reference
intensity at wavelength λ.
Figure 6-1: Typical absorbance setup. The light source (far right) sends light via an input fiber into a cuvette in a cuvette
holder (bottom center). The light interacts with the sample. The output fiber carries light from the sample to the
spectrometer (top center), which is connected to the PC (far left).
Absorbance is also proportional to the concentration of the substance interacting with the light (this is known as
Beer’s Law). Common absorption applications include the quantification of chemical concentrations in aqueous or
gaseous samples.
Follow the steps below to take an absorbance measurement using OOIBase32:
1. Place OOIBase32 in scope mode by clicking the scope mode icon on the toolbar or selecting Spectrum |
Scope Mode from the menu bar.
2. Ensure that the entire signal is on scale. The intensity of the reference signal should peak at about 3500
counts. If necessary, adjust the integration time until the intensity is approximately 3500 counts.
(Continued)