Professor Christopher Elles named August 2024 Sutton Family Research Impact Award recipient

The Department of Chemistry congratulates Professor Christopher Elles on receiving the August 2024 Sutton Family Research Impact Award!

The Sutton Award is a monthly competition among chemistry faculty. Every month, the Chemistry Department Chair and Associate Chairs review the peer-reviewed papers published by chemistry faculty from the three previous months to select a winner. The recipient receives a $500 cash prize and is featured on the departmental website.

 For a full list of winners, visit our Sutton Family Research Impact Award webpage.

A Single-Shot Technique for Measuring Broadband Two-Photon Absorption Spectra in Solution

By Prasenjit Srivastava and Christopher G. Elles

 Analytical Chemistry, 96, 11121-11125 (2024)

Biological imaging, 3D printing, and photodynamic therapy all take advantage of a process called two-photon absorption (2PA) to activate target molecules with very high spatial resolution. The 2PA process requires high intensity irradiation that is easily achieved in the tight focus of a laser beam. This allows molecules to be excited only in the focal volume of the laser, which can be smaller than the size of a cell. The target molecule to be excited also needs to have the right properties to allow it to absorb the two photons with higher probability than the surrounding material. Such molecules are said to have a large 2PA cross section, but there is also a requirement that the 2PA cross section matches the wavelength of the laser light.

Considering the important applications that are enabled by the 2PA process, there has been significant effort to develop new molecules with large 2PA cross sections that are both matched with favorable laser wavelengths and that remain suitable for the intended applications. Unfortunately, the development of new dyes is often limited by the difficulty in measuring the two-photon absorption properties of a molecule. To overcome this challenge, the Elles Group has been working to develop new methods to measure the two-photon absorption spectra of target molecules.

This latest contribution from the group presents a significant improvement in the technique that the group has been working to develop in recent years. The new approach allows the full 2PA spectrum of a molecule to be measured using a single pair of laser pulses. The single-shot method enables more rapid data collection with fewer complications. Not only does this provide a significant improvement in the quality of the results, it also raises the possibility of making the measurement more widely accessible. Ultimately, the group hopes to develop their approach to 2PA spectroscopy into a user-friendly design that can be implemented by synthetic groups that make the target molecules, but don’t necessarily have the expertise in laser spectroscopy that is currently necessary for such measurements. The work was published in the journal Analytical Chemistry.

Figure: Image representing the new single-shot approach for measuring two-photon absorption (2PA) spectra of molecules in solution.