In this project funded by the Experimental Physical Chemistry Program and the Office of International Science and Engineering, Professor Susanne Ullrich of the University of Georgia and her research group will employ time-resolved photoelectron spectroscopy (TRPES) to study the relaxation pathways of photoexcited biologically relevant molecules. The Ullrich group will collaborate with Professor Vasilios Stavros of Warwick University in Coventry, UK, who is a specialist in a technique called time-resolved velocity map imaging (TRVMI). The combination of these two ultrafast techniques is expected to reveal the order underlying the many overlapping electronic states typical of polyatomic molecules and how these states interact with one-another. Initial experiments will focus on 1H-Pyrrole, 1H-Pyrazole, and 1H-imidazole species, followed by research on the DNA base species.
The results of this research will have broad implications in photochemistry, photobiology, and even nanotechnology. In addition, this US - UK collaborative effort will involve the exchange of professors and students between the two laboratories. Students involved in the research will therefore benefit from a highly interdisciplinary (chemistry, physics, biology) and international experience as well.
Photochemistry plays an integral part in our everyday's lives whether it is in biological processes or industrial applications. A biological system of profound interest is DNA as it comprises the genetic coding material of life. Our skin is subject to exposure to ultraviolet (UV) radiation from the sun. The energy of the UV light is absorbed by biomolecules in our skin such as our DNA where it can induce gene mutations which are considered the initial step that may lead to skin cancer. In this NSF supported project, our group has used laser spectroscopic techniques to develop a molecular level understanding of how DNA bases and their precursors respond to UV excitation and protect themselves against photodamage. Specifically, our measurements have determined the deactivation pathways that dissipate the UV energy into harmless heat and the timescales of such processes which can occur as fast as a trillionth of a second. This work was performed by three graduate and two undergraduate students who have been trained in optics, electronics, vacuum technologies and scientific computing under the mentorship of the principal investigator. Our research findings have been disseminated to the scientific communities through publications and presentations and to the public through outreach activities involving local schools. For example, we have performed fourteen "flashes and bangs" science shows at middle schools and provided four summer research internships to high school teachers and students.
