ThermoFisher Scientific DXR xi, Руководство пользователя

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3
OMNICxi Software Operation
Acquire and Analyze Data
152 DXRxi User Guide Thermo Scientific
Table 35. Acquisition window, standard acquisition settings in Live Spectrum mode
Feature Description
Laser power Laser energy at the sample in milliwatts (0 blocks the laser).
Highest available laser power settings depends on the installed
laser.
Higher power increases the height of spectral peaks. However,
some samples may be burned or damaged when laser power is too
high.
Exposure time Laser exposure time for each acquired spectrum in fractions of a
second. Also indicates the speed of acquisition in Hz (i.e., number
of spectra acquired per second).
Longer exposure times may increase the height of spectral peaks
but will also increase scan time.
Number of scans Number of scans used to produce the acquired spectrum. Spectra
collected from multiple scans are averaged.
Using a higher number of scans setting may reduce noise in the
spectral baseline due to signal averaging. However, increasing
number of scans also increases the time required to acquire the
data.
Aperture Defines the size of the Raman beam entrance slit or pinhole. The
beam passes through the aperture on its way to the instrument
detector. Available settings:
• 25 μm confocal pinhole . Maximizes spatial resolution
(ability to discriminate very small changes in a sample) and
spectral resolution (ability to resolve narrow bands in the
spectrum), but allows less Raman energy from the sample
which may decrease signal intensity. Recommended for
analyzing samples with fine detail, cross sectional analysis,
and when using a high resolution grating.
• 50 μm confocal pinhole . Increases Raman energy at the
detector but may reduce spatial and spectral resolution.
Recommended when using higher image pixel size settings
and working with a full range grating.
• 25 μm (or 50 μm) slit . Maximizes Raman energy at the
detector which produces higher quality spectra (higher
signal-to-noise ratio) but may reduce spatial and spectral
resolution. Use the smaller (25 μm) slit to improve spectral
resolution. Do not use slit settings for cross sectional analysis.