Issue 24, 2014

The effect of high light intensities on luminescence lifetime based oxygen sensing

Abstract

This study highlights possible errors in luminescence lifetime measurements when using bright optical oxygen sensors with high excitation light intensities. An analysis of the sensor with a mathematical model shows that high light intensities will cause a depopulation of the ground state of the luminophore, which results in a non-linear behaviour of the luminescence emission light with respect to the excitation light. The effect of this non-linear behaviour on different lifetime determination methods, including phase-fluorometry, is investigated and in good agreement with the output of the model. Furthermore, the consequences of increasingly high light intensities on phase fluorometric lifetime measurements are illustrated for different oxygen sensors based on benzoporphyrin indicators. For the specific case of PdTPTBPF-based sensors an error as high as 50% is possible under high light conditions (0.25 mol m−2 s−1 ≈ 50 mW mm−2). A threshold of applied excitation light intensity is derived, thus enabling the point at which errors become significant to be estimated. Strategies to further avoid such errors are presented. The model also predicts a similar depopulation of the ground state of the quencher; however, the effect of this process was not seen in lab measurements. Possible explanations for this deviation are discussed.

Graphical abstract: The effect of high light intensities on luminescence lifetime based oxygen sensing

Supplementary files

Article information

Article type
Paper
Submitted
10 Jun 2014
Accepted
19 Sep 2014
First published
22 Sep 2014

Analyst, 2014,139, 6569-6579

The effect of high light intensities on luminescence lifetime based oxygen sensing

C. Larndorfer, S. M. Borisov, P. Lehner and I. Klimant, Analyst, 2014, 139, 6569 DOI: 10.1039/C4AN01058B

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