horiba FluoroMax-3, Руководство по эксплуатации

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FluoroMax-3 v. 3.1 (6 Mar 2006) Glossary
13-6
High-pass filter
Optical component that passes light of a higher wavelength.
Increment
The spacing between adjacent measurement points in an acquisition.
Typically, increments take the form of wavelength (nm) or time (s or
ms).
Inner-filter effect
The scattering of the excitation or emission beam from a concen-
trated sample by the individual molecules in the sample. This reduces
the apparent signal intensity from the sample creating an artifact in
the data. For this reason, we recommend using concentrations of
<0.05 OD in a 1-cm-pathlength cell. Samples measured in higher
concentrations should be measured in a reduced-pathlength cell, or in
front-face mode.
Integration time
The amount of time that each data point is collected from the detec-
tor(s), specified in either seconds or milliseconds. Longer integration
times can help improve the signal-to-noise ratio for a measurement,
while shorter integration times reduce the amount of time required
for a scan.
Internal conversion
Electronic transitions within an excited molecule that do not result in
emission. Also called a “non-radiative transition”, this usually in-
volves changes in vibrational levels.
Intersystem crossing
The electronic transition from the excited singlet state to the excited
triplet state before returning to the ground state. This transition in-
volves a change of spin that is quantum-mechanically forbidden, giv-
ing a much longer timescale than fluorescence. This transition causes
phosphorescence on the timescale of microseconds to seconds.
Intrinsic fluorescence
The natural fluorescent properties of molecules.
Jab ł onski (energy) dia-
gram
A diagram that illustrates various energy levels and electronic transi-
tions available in a particular molecule. Possible paths for fluores-
cence, phosphorescence, and non-radiative transfers are shown on
this diagram, along with the various vibrational sub-levels available
around each energy level.
Laser
A monochromatic light source that provides high excitation intensity.
Linearity
(1) Signal response; the desired response from a light detector is a
linear relationship. For example, when detector response is linear,
if the light intensity doubles, the detected signal also doubles.
Most detectors exhibit non-linear behavior near saturation. On the
FluoroMax
®
-3, the emission photomultiplier tube is linear up to 2
million counts per second. Above this, pulse pileup occurs on the
photon-counting module (when multiple photons are counted as
one). This results in a non-linear response, and the detector effi-
ciency drops.
(2) Spectral positioning accuracy or tracking error of a spectrometer
drive mechanism.
See
Spectral Calibration
.