Update of a Classic: A Compact Fiber-Optic-Based Laser Luminescence Instrument To Measure Bimolecular Quenching Rate Constants

We have constructed a compact laser-based spectrometer that confines the laser light to a fiber-optic and is suitable for use in an open undergraduate physical chemistry laboratory. The instrument employs currently available technology and is relatively inexpensive compared to research-grade instruments. Nanosecond time resolution is achieved, and we have successfully utilized the spectrometer for a classic laser experiment to measure the bimolecular quenching rate constant for the photoexcited tris(2,2′-bipyridyl)ruthenium(II) complex by Fe(III) in aqueous solution using Stern–Volmer analysis. The results are very reproducible with small experimental error and compare well with published values for quenching rate constants of the Ru(II) complex. The experiment exposes students to time-resolved laser measurements that rely on a photochemical kinetic analysis commonly taught as part of the physical chemistry curriculum.

Reference

Mary Sever, Mark A. Young*, J. Chem. Educ. 2025, 102, 3, 1230–1236, doi.org/10.1021/acs.jchemed.4c01200