Horiba Scientific FluoroMax-4 Operation Manual page 93

® ®
FluoroMax -4 & FluoroMax -4P with USB rev. D (30 Jul 2012)
Selecting the appropriate bandpass
The bandpass (wavelength spread) affects the resolution of your spectra. If the
bandpass is too broad, narrow peaks separated by a small change in wavelength may be
unresolved. For example, for two 2-nm peaks 5 nm apart, and a bandpass of 10 nm, one
broad peak, instead of two well-defined ones, is visible.
By adjusting the slit widths, the intensity and bandpass of the light is controlled. The
slits of the excitation spectrometer determine the amount of light that passes through
the excitation spectrometer to the sample. The emission spectrometer slits control the
amount of fluorescence recorded by the signal detector. Signal level is proportional to
the square of the slit width, that is,
signal level ∝ (slit width)
Bandpass is calculated using the following formula:
bandpass (nm) = slit width (mm) × dispersion (nm/mm)
A FluoroMax
gratings, has a dispersion of 4.25 nm/mm.
For steady-state fluorescence measurements, set the entrance and exit slits the same for
a monochromator. (This occurs automatically when using bandpass units in
FluorEssence™.) For biological samples that may photobleach, try narrowing the exci-
tation slits and opening the emission slits wider.
2
®
-4, which has a single-grating monochromator and 1200 grooves/mm
5-11
Optimizing Data