Agilent Technologies 1100 Series Reference Manual page 238

7
Introduction to the Fluorescence Detector
When a more complex molecule transforms from its ground energy state into
an excited state, the absorbed energy is distributed into various vibrational
and rotational sub-levels. When this, same molecule returns to the ground
state, this vibrational and rotational energy is first lost by relaxation without
any radiation. Then the molecule transforms from this energy level to one of
the vibrational and rotational sub-levels of its ground state, emitting light, see
Figure
and for emission its λ
Figure 74
Photoluminescence is the collective name for two phenomena, fluorescence
and phosphorescence, which differ from each other in one characteristic
way--the delay of emission after excitation. If a molecule emits light 10
10
molecule emits light longer than 10
process was phosphorescence.
240
74. The characteristic maxima of absorption for a substance is its λ
EM
Relationship of Excitation and Emission Wavelengths
-5
seconds after it was illuminated then the process was fluorescence. If a
.
-3
seconds after illumination then the
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