Two-Photon Absorption Spectroscopy on Curcumin in Solution: A State-of-the-Art Physical Chemistry Experiment

Herein we report on the implementation of the open-aperture Z-scan method for measuring two-photon absorption (TPA) as a laboratory experiment for the undergraduate Physical Chemistry lab. The objectives of this experiment are (i) to expose undergraduates to the concept of TPA, (ii) to teach the principles of the Z-scan technique, and (iii) to allow students the opportunity to measure TPA cross-section of a naturally occurring biomarker, curcumin, using open-aperture Z-scan. After completion of the experiment, students can compare and contrast the processes of one- and two-photon absorption as well as fluorescence and upconversion. In addition, they can explain the basic experimental "apparatus" (experimental arrangement) and procedure for performing the open-aperture Z-scan. Assessment of student perception showed that students appreciated the opportunity to be exposed to techniques that build on what they learn in the classroom and have applications in research laboratories as well as practical settings.