FlashPhotol: Using a Flash Photolysis Apparatus Simulator To Introduce Students to the Kinetics of Transient Species and Fast Reactions

Abstract

FlashPhotol is an educational software package that introduces students to the kinetics of transient species and fast reactions. This is achieved by means of a computer-simulated flash photolysis apparatus that comprises all major functional elements and that students can use to perform various experiments. The experimental interface presents a visual representation of the monitoring light beam transmission through the sample cell as well as the corresponding transient concentration after excitation thereby enabling students to fully appreciate the fundamental processes on which the technique relies. Experiments in the package also reinforce students’ understanding of the Beer–Lambert law and illustrate how an absorbance value is produced from internal signals within an instrument. The software includes: (i) a fully contained tutorial on the technique of flash photolysis; and (ii) a procedure for each of the experiments that can be performed using the simulator along with an example results analysis in each case. It is anticipated that instructors may wish to use the simulator for lecture demonstrations, especially in demonstrating the transient process occurring in the sample cell following flash irradiation.

Flash Photolysis Experiment of o-Methyl Red as a Function of pH: A Low-Cost Experiment for the Undergraduate Physical Chemistry Lab

“…In this paper, an experiment is presented in which students excite the azobenzene derivative o -methyl red with a laser pointer and monitor the spectral dynamics using a UV–vis spectrometer with a CCD array detector. Flash photolysis experiments have been proposed for use in teaching laboratories before, − but this experiment takes advantage of the slow isomerization reaction rate of o -methyl red in basic solutions and the ability of a spectrometer with a silicon CCD array detector to quickly collect spectra to examine the spectrum as a function of time. , Azobenzene derivatives are ideal for introducing kinetics concepts to undergraduate physical chemistry students because the rate to re-form the trans conformer from the photoexcited cis conformer is very molecule, solvent, and temperature dependent. ,− In this experiment, students observe how transient spectra change when the solvent is used as a reference and when the solution is used as a reference. Transient absorption dynamics, transient bleach dynamics, and an isosbestic point are observed.…”