Tag Archives: fluorescence

Absorbance and Fluorescence Detection for HPLC Separations

One popular HPLC detector takes advantage of an analyte’s UV/Vis absorption spectrum. These detectors range from simple designs, in which the analytical wavelength is selected using appropriate filters, to a modified spectrophotometer in which the sample compartment includes a flow … Continue reading

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Alizarin Garnet R

Except for a few metal ions, most notably UO2+, most inorganic ions are not sufficiently fluorescent for a direct analysis. Many metal ions may be determined indirectly by reacting with an organic ligand to form a fluorescent, or less commonly, … Continue reading

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Fluorescence and Phosphorescence Instrumentation

The basic instrumentation for monitoring fluorescence and phosphorescence—a source of radiation, a means of selecting a narrow band of radiation, and a detector—are the same as those for absorption spectroscopy. The unique demands of both fluorescence and phosphorescence, however, require … Continue reading

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Fluorescence Emission Spectrum for Tyrosine

A photoluminescence spectrum is recorded by measuring emission intensity  as a function of either the excitation wavelength or the emission wavelength. An excitation spectrum is obtained by monitoring emission at a fixed wavelength while varying the excitation wavelength. When corrected … Continue reading

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Pathways for Deactivating an Excited State Without Emission

Shown here is an illustration of the energy level diagram for a molecule exhibiting pathways for the deactivation of an excited state: vr is vibrational relaxation; ic is internal conversion; ec is external conversion; and isc is an intersystem crossing. … Continue reading

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Singlet and Triplet States

Photoluminescence is divided into two categories: fluorescence and phosphorescence. A pair of electrons occupying the same electronic ground state have opposite spins and are said to be in a singlet spin state; see (a) in the illustration below. When an … Continue reading

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