FLS980 Archives | Edinburgh Instruments


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Application Note: Temperature Dependence of Phosphors via Photo-and Thermo-Luminescence

Inorganic phosphors are widely used in lighting and display technologies and their emission properties are commonly characterised using photoluminescence spectroscopy. Phosphors generally operate at elevated temperatures and it is therefore important to understand how the emission properties change with temperature. In this application note, the temperature dependence of BAM:Eu phosphor is studied using the FLS980 Photoluminescence Spectrometer.

Tryptophan and Non-Tryptophan Fluorescence of the Eye Lens Proteins Provides Diagnostics of Cataract at the Molecular Level

Anna Gakamsky1, Rory R. Duncan2, Nicola M. Howarth2, Baljean Dhillon3, Kim K. Buttenschön4, Daniel J. Daly4 & Dmitry Gakamsky2

The chemical nature of the non-tryptophan (non-Trp) fluorescence of porcine and human eye lens proteins was identified by Mass Spectrometry (MS) and Fluorescence Steady-State and Lifetime spectroscopy as post-translational modifications (PTM) of Trp and Arg amino acid residues. Fluorescence intensity profiles measured along the optical axis of human eye lenses with age-related nuclear cataract showed increasing concentration of fluorescent PTM towards the lens centre in accord with the increased optical density in the lens nucleolus. Significant differences between fluorescence lifetimes of “free” Trp derivatives hydroxytryptophan (OH-Trp), N-formylkynurenine (NFK), kynurenine (Kyn), hydroxykynurenine (OH-Kyn) and their residues were observed. Notably, the lifetime constants of these residues in a model peptide were considerably greater than those of their “free” counterparts. Fluorescence of Trp, its derivatives and argpyrimidine (ArgP) can be excited at the red edge of the Trp absorption band which allows normalisation of the emission spectra of these PTMs to the fluorescence intensity of Trp, to determine semi-quantitatively their concentration. We show that the cumulative fraction of OH-Trp, NFK and ArgP emission dominates the total fluorescence spectrum in both emulsified post-surgical human cataract protein samples, as well as in whole lenses and that this correlates strongly with cataract grade and age.

Technical Note: Excitation-Emission Spectroscopy with Charge Coupled Detectors

Excitation-emission spectroscopy becomes increasingly useful in the study of photo-luminescent materials. The spectral selectivity of the technique enables the quantification of multiple emitting sites in rare-earth doped crystals, as well as the rapid acquisition of polycyclic aromatic hydrocarbons (PAH) in contaminated water.