Ocean Optics CHEM2000 - Manual (Page 12)

2: Using OOIChem Software
Display Functions
Several functions are accessed not through the menu but through buttons and task bars directly on the
display screen, on the top and to the right of the graph area. (The resolution of your computer's monitor
must be 800 x 600 or better to view OOIChem software.) From the display screen, you can choose a
mode of operation, configure the cursor, configure the graph, enter acquisition parameters, choose a mode
to acquire data, take reference, dark, and sample scans of your sample, and scale the graph.
Spectrometer Channel Selection
The Spectrometer Channel area allows you to animate the window for a specific spectrometer channel.
The Maxwell is a single spectrometer channel system. Select Master.
Mode of Operation
Scope
The signal graphed in Scope Mode is the raw voltage coming out of the A/D converter. Once you open
OOIChem and it begins to acquire data, you see the raw voltage from the detector expressed in A/D
counts. This spectral view mode is unique to Ocean Optics. It allows you to control signal processing
functions before taking absorbance, transmission, and relative irradiance measurements. Be careful when
using this mode, as it represents a combination of several factors: the intensity
of the light source, the reflectivity of the grating and the mirrors in the
spectrometer, the transmission of the fibers, the response of the detector, and the
spectral characteristics of the sample.
Scope Mode should primarily be used when selecting signal acquisition
parameters such as integration period, averaging and boxcar smoothing; and
when taking dark and reference scans.
Absorbance
Selecting this mode switches the spectral window into Absorbance Mode. Before this can occur, both a
dark and reference scan must be stored in Scope Mode (see
Experiment Tutorial
). Absorbance is
calculated by the following equation. When this equation is evaluated for each pixel of the detector, the
absorbance spectrum is produced.
S
(
λ
-D
λ
A
λ
= - log
10
R λ
-D
λ
)
Where:
S = Sample intensity at wavelength λ
D = Dark intensity at wavelength λ
R = Reference intensity at wavelength λ
6 PRELIMINARY DRAFT 105-00000-CHM-02-0405