Chemists Find the Missing Link of Polyene Photophysics

A team of chemists has discovered how butadiene, the smallest among a class of molecules called polyenes, dynamically responds to the absorption of light. Elucidating the dynamics of this smallest polyene is an active area of study since it represents a stepping stone to larger and more complicated polyenes. And a better understanding of the fundamental physics of polyenes as a whole might reveal new strategies for rationally designing molecules with improved solar energy conversion efficiencies.

“The optical properties of butadiene had been the subject of more than 50 years of study. Despite this long history, the dynamics of butadiene had remained controversial: it didn't seem to behave like either the smaller ethylene molecule or the longer polyenes,” says William Glover, Assistant Professor of Chemistry at NYU Shanghai and a member of the NYU-ECNU Center for Computational Chemistry at NYU Shanghai. “This motivated our groups to form an experiment/theory collaboration to study this molecule both with ultrafast laser spectroscopy and first-principles computational simulations.”

Independently, two studies from the theoretical groups of Glover and Martinez from Stanford University, and the experimental group led by Stolow from the University of Ottawa found that butadiene's behavior is precisely intermediate between ethylene and the longer polyenes and this arises due to a coincidental near-exact match in two of its energy levels. “This means we can really think about butadiene being the ‘missing link’ between short and long polyenes,” says Glover.

“This collaboration is key. We each independently came up with the same results. Dramatic technical advances in both experiment and theory have allowed us to finally solve the long-standing puzzle of electronic dynamics in butadiene,” reflects Stolow during an interview with the AIP Publishing.

Both studies have been published online in the same issue of the Journal of Chemical Physics where Prof. Glover is one of the authors of the experimental study and the first author of the theoretical study.


Journal Reference:

A. E. Boguslavskiy, O. Schalk, N. Gador, W. J. Glover, T. Mori, T. Schultz, M. S. Schuurman, T. J. Martínez, A. Stolow*, Excited state non-adiabatic dynamics of the smallest polyene, trans 1,3-butadiene. I. Time-resolved photoelectron-photoion coincidence spectroscopy”, J. Chem. Phys. 148, 164302 (2018) 

W. J. Glover, T. Mori, M. S. Schuurman, A. E. Boguslavskiy, O. Schalk, A. Stolow, T. J. Martínez*, Excited state non-adiabatic dynamics of the smallest polyene, trans 1,3-butadiene. II. Ab initio multiple spawning simulations”, J. Chem. Phys. 148, 164303 (2018)