 The
UV-visible-NIR
microspectrometer is a
single beam instrument.
It corrects for instrumental
and sample variables by
first acquiring a dark scan
(D) that measures the
electronic noise of the
system. A reference
spectrum is then acquired.
This is a spectrum of the
reference material (R) and
includes the optical
characteristics of the
reference material as well
as those of the instrument
optics and light sources.
A sample spectrum (S) is then
acquired and the following
calculations result in a
corrected spectrum.
Transmittance
Transmittance
calculates a transmission
spectrum from a sample and
reference single-beam
spectra.
From Two Single-Beam Spectra:
Transmission can produce a
transmission spectrum from
two single-beam spectra
using the following formula:
where R is the single beam
spectrum of the reference
material, S is the single
beam spectrum of the sample
and D is the dark counts of
the system.
From Absorbance Data:
A transmission
spectrum can be generated from an absorbance
spectrum using the following
formula:
where A is the absorbance
value. This is a calculation from data that
has already been collected.
Absorbance
Absorbance
calculates
an absorbance spectrum from
a sample and reference
single-beam spectra or from
a transmission spectrum.
From Two Single-Beam Spectra:
Absorbance can produce an
absorbance spectrum from
two single-beam spectra
using the following formula:
where R is the single beam
spectrum of the reference
material, S is the single
beam spectrum of the sample
and D is the dark counts of
the system.
From Transmission
Data:
Absorbance can also generate
an absorbance spectrum from
a transmission spectrum
using the following formula:
where %T is the percent
transmittance
value. This is a calculation from data that
has already been collected.
Reflectance
Reflectance
calculates a reflectance
spectrum from a sample and
reference single-beam
spectra or from an
log 1/R spectrum.
From Two Single-Beam Spectra:
Reflectance can produce a
reflectance spectrum from
two single-beam spectra
using the following formula:
where R is the single beam
spectrum of the reference
material, S is the single
beam spectrum of the sample
and D is the dark counts of
the system.
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