Principles of Fluorescence Spectroscopy

Appendix I
Corrected Emission
Spectra
A relatively limited number of corrected emission spectra
are available. In this Appendix we include the well-documented
corrected spectra. It is not possible to state which
are the "most correct." Corrected spectra can be interchanged
from photons per wavenumber interval I(ν) to photons
per wavelength interval I(λ) using I(λ) = I(ν)λ –2 , followed
by normalization of the peak intensity to unity. Most
of the compounds listed below satisfy the suggested criteria
for emission spectral standards, which are as follows:
1. Broad wavelength emission with no fine
structure
2. Chemically stable, easily available and
purified
3. High quantum yield
4. Emission spectrum independent of excitation
wavelength
5. Completely depolarized emission.
1. EMISSION SPECTRA STANDARDS FROM 300
TO 800 NM
Corrected emission spectra on the wavelength scale were
reported for six readily available fluorophores in neat solvents
(Table I.1). The emission spectra of these standards
overlap, providing complete coverage from 300 to 800 nm.
For convenience the numerical values of the emission spectra
are given in Table I.2. The values are plotted in Figure
I.1, and the chemical structures are given in Figure I.2.
These correct spectra cover almost all needed wavelengths.
It is recommended that these spectra be adopted as
the accepted standards for determination of instrument
corrections factors and for calculation of corrected emission
spectra.
2. β-CARBOLINE DERIVATIVES AS
FLUORESCENCE STANDARDS
Corrected emission spectra of the carboline derivatives
shown in Figure I.3 and I.4 were published. 2 All compounds
were measured in 0.1 N H 2 SO 4 , except for 2-methylharmine,
which was measured in 0.01 N H 2 SO 4 , 25°C. Corrected
emission spectra were reported in graphical form
(Figure I.3) and in numerical form (Table I.3). Quantum
yields and lifetimes were also reported (Table I.4). Quantum
yields were determined relative to quinine sulfate in 1.0
Figure I.1. Corrected emission spectra of six standards from [1].
From left to right the spectra are for tryptophan, α-NPO, TPB,
coumarin, DCM, and LDS 751.
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