C&CB Seminar - D. Hans-Peter Loock, Department of Chemistry, Queen’s University
TITLE: New Instruments and Applications of Fluorescence Excitation-Emission-Matrix Spectroscopy
Date: Thursday October 10, 2019
Time: 1:30 – 2:30 p.m.
Place: ABB 163
Host: Dr. Kalaichelvi Saravanamuttu
In fluorescence excitation-emission-matrix spectroscopy (EEMS) the entire dispersed fluorescence spectrum is recorded at a large number of excitation wavelengths and the resulting 3-dimensional spectrum is analysed with chemometric analysis techniques to identify the classes of fluorophores.
The technique is several decades old and is well-established in comparative analytical studies, for example in the food and beverage industries or in environmental sciences. Relatively unexplored is its potential in chemical kinetics. I will demonstrate that the EEM technique when coupled with parallel factor (PARAFAC) analysis provides quantitative information on the identity, concentration and reaction rates of fluorescing compounds in several industrial liquids, such as jet fuel, lubricant oils, crude oil and even liquid scintillators for the Nobel-winning SNO-Lab collaboration. These measurements can be performed in neat liquids and in ambient environments using a home-built fiber probe.
To accelerate the data acquisition process we designed a new instrument that uses a highly multiplexed approach to the irradiation and fluorescence detection. We use a programmable digital micromirror array to irradiate our samples with the full spectrum of the excitation source, but through a Hadamard spectral filter. After performing the inverse Hadamard transformation we obtain an EEM spectrum having a spectral resolution of 30 to 500 spectral excitation channels. EEM Spectra can then be acquired in about 1-10 s, i.e. about 200-times faster compared to a conventional instrument. Experimental results obtained in fast (stop-flow) kinetics will be used as examples for possible future applications.