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
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
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
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
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