ThermoFisher Scientific Vanquish VC-D50, Operating Manual

Page: 102 / 188

6 • Operation
Page 102 Fluorescence Detectors (VC-D50, VC-D51, VF-D50, VF-D51)
Operating Manual
Emission Scan
The wavelength on the excitation monochromator is kept constant,
while the emission monochromator scans a wavelength range. The
result is an emission spectrum of the sample.
Synchronous Scan
A user-defined excitation wavelength range is scanned, while the
emission wavelength is scanned synchronously with a fixed user-defined
offset. This allows you to determine a suitable wavelength pair for initial
experiments. However, the optimum excitation and emission
wavelengths must be determined by using separate excitation scans and
emission scans.
To perform a single spectrum scan
For information on spectrum scans as well as instrument method
examples, refer to the
Chromeleon Help .
CAUTION
• During the scan process, no other commands can be sent to the
fluorescence detector.
• The duration of the scan process depends on the range to be
scanned and the selected scan speed.
• Before each scan, select a detector sensitivity, using the
ScanSensitivity parameter. If the detector sensitivity is set too high,
no spectra will be saved and a message appears in the audit trail.
• Artefacts may occur when scanning near extreme changes in the
spectrum (which frequently occur near the excitation wavelength),
for example, when scanning the Raman emission spectrum of water
near the excitation of 350 nm. In this case, select a greater distance
between the wavelength scan range and the edge (greater than the
minimum of 20 nm). For the Raman emission scan, for example,
select a start wavelength of 385 nm.
6.7.5 FL Field Acquisition
FL Field Acquisition can help you in determining retention times and
emission maxima. As opposed to single spectrum scans, where the
selected spectral range is scanned
once , the spectral range is scanned
continuously, resulting in a spectral field similar to a 3D field of a diode
array detector. Available scan modes are:
• Excitation
• Emission
• Synchronous