Curcumin, a naturally occurring biomarker, was recently shown to have a significantly large two-photon absorption cross section in a range useful for bioimaging and photodynamic therapy. Considering the high level physical chemistry concepts involved in the experiment, state-of-the-art applications and the non-toxic nature of this sample, we decided to bring this experiment into the undergraduate laboratory. Herein we report on the implementation of the open aperture Z-scan method for measuring two-photon absorption (TPA) of curcumin as a laboratory experiment for the undergraduate Physical Chemistry Lab. Student learning objectives in this experiment are to: i) understand the concept of TPA and compare it to one-photon absorption, ii) to explain the principles of the Z-scan technique and iii) to measure TPA cross section of a naturally occurring biomarker, curcumin, using open-aperture Z-scan. After implementation of the experiment, students could compare and contrast the processes of one- and two-photon absorption as well as fluorescence and upconversion. In addition, they could explain the basic experimental set-up and procedure for performing the open-aperture Z-scan and discuss the use of TPA in biological and optical applications. Assessment of student perception showed that students appreciated the opportunity to be exposed to ultramodern techniques that build on what they learn in the classroom and have applications in research labs as well as practical settings.

Two-photon absorption spectroscopy on curcumin in solution: A state-of-the-art physical chemistry experiment

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.