Positional Isomerization (IMAGE) Princeton University Caption This image shows the contra-thermodynamic positional isomerization of olefins enabled by excited-state redox catalysis and chromium catalysis. Credit Courtesy of the Knowles Lab Usage Restrictions For media use only. License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.