Geoscience Reference
In-Depth Information
L2
second experiment
third experiment
P3
L3
P2
500
550
600
650
Wavelength (nm)
Figure 5.23. Graphic illustration of the three-measurement technique.
•
Integrate the spectrum from the background (zero level) before the peak to the same
background after the peak to give the total number of photons per second in the wave-
length range of the peak, and therefore available to the sample
L
1.
Store the spectrum and the integrated photons per second signal rate.
•
Measurement 2: Re-Absorption Signal - Sample is present in the IS
.
Place the sample into the IS but in the OFF position, such that it is not directly illumi-
•
nated by the excitation light.
Excitation monochromator is set to the excitation wavelength.
•
•
Emission scan across the spectral range, including the excitation peak.
•
Determine the peak wavelength from the measurement.
•
Correct the spectrum for the integration period to give the number of photons per
second.
Integrate two regions of the spectrum:
•
•
The excitation spectrum from the back ground (zero level) before the peak to the same
background after the peak to give the total number of photons per second in the wave-
length range of the peak, and therefore the number of excitation photons that are not
reabsorbed by the sample.
L
2
The PL emission spectrum from the background (zero level) before the peak to the
•
same background after the peak to give the total number of photons per second in the
wavelength range of the peak, and therefore the number of emission photons that are
emitted by the sample.
P
2
Store the spectrum and the two integrated photons per second signal rates,
•
L
2 and
P
2.
