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Fluorolog-3 v. 2.2 (12 Jul 2002)
Glossary
16-1
16: Glossary
3D excitation/emission
display
This maps a specified emission-scan wavelength range using various
excitation wavelengths.
3D synchronous/offset
scan
A scan that maps a specified synchronous scan using various offset
wavelengths between the spectrometers.
Absorption
Transition, when a photon enters a molecule, from the ground state
to the excited singlet state. This process typically occurs in ~10
–15
s.
Absorbance
The extent of absorption by a substance. Absorbance,
A
, is –log
T
,
where
T
is the transmittance of the sample. Absorbance is also syn-
onymous with optical density (OD). Absorbance can be calculated
using the Beer-Lambert Law:
OD =
A
=
ε
cl = –
log
T
ε
= the extinction coefficient (
M
–1
cm
–1
)
c
= sample concentration (
M
)
l
= path length (cm)
Bandpass
The wavelength range of light passing through the excitation and
emission spectrometers. The wider the bandpass, the higher the sig-
nal intensity.
Bandpass filter
Optical element that selectively transmits a narrow range of optical
wavelengths.
Bioluminescence
Emission of light originating from a chemical reaction in a living
organism.
Blaze wavelength
Wavelength at which a grating is optimized for efficiency. Gener-
ally, the gratings are efficient to 2/3 before the blaze wavelength to
twice the blaze wavelength. The excitation and emission gratings are
blazed in the UV and visible respectively.
Chemiluminescence
Emission of light originating from a chemical reaction.
Color effect for pulse
technique
Time-dependent wavelength distribution of the lamp pulse.
Color effect for phase-
modulation technique
Phase of the excitation and the degree to which it is modulated.
Corrected emission scan
An emission scan corrected for the wavelength characteristics of the
emission spectrometer and the response of the signal detector. To
obtain a corrected emission scan, an emission spectrum is multiplied
by the emission correction factors. A set of emission correction fac-
tors is supplied with the instrument and stored as
mcorrect.spt
on the software disks.
Corrected excitation scan
An excitation scan corrected for the wavelength characteristics of the
xenon lamp, the aging of the xenon lamp, and the gratings in the ex-
citation spectrometer. To obtain a corrected excitation scan, the de-
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