Transient-Absorption Spectroscopy of Cis–Trans Isomerization of <i>N</i>,<i>N</i>-Dimethyl-4,4′-azodianiline with 3D-Printed Temperature-Controlled Sample Holder

Abstract

The laboratory unit demonstrates a project-based approach to teaching physical chemistry laboratory where upper-division undergraduates carry out a transient-absorption experiment investigating the kinetics of cis–trans isomerization of N, N -dimethyl-4,4′-azodianiline. Students participate in modification of a standard flash-photolysis spectrometer by adding a temperature-controlled sample holder. The sample holder design is open-source and can be reproduced with the 3D-printing technology. Students build the experimental setup, perform the transient spectroscopy experiment, and analyze the obtained kinetics data to estimate the activation energy, enthalpy, entropy, and Gibbs free energy of cis–trans isomerization of N, N -dimethyl-4,4′-azodianiline.