In a lot of ways, understanding quantum mechanical equations in an effort to predict what will happen between reactants such as atoms and molecules resulting in complex phenomena in chemistry can be exhausting, and mind-boggling to many. Yet, without the theoretical insights, experimental chemists would largely be unable to understand what they are observing.
Researchers at The University of New Mexico, led by distinguished professor of chemistry Hua Guo, have been working with experimentalists to help them gain an understanding by providing theoretical interpretations of experimental observations.
“When scientists probe molecules they see spectral features, but it is very difficult to interpret those features because they are just lines in the spectrum,” said Guo. “That’s where we come in and provide a theoretical interpretation of their experimental observations.”
One such joint study by Guo’s team is published recently with a group of researchers at Cal-Berkeley in the prestigious journal Nature Chemistry.
Characterizing the transition state of a reaction has long been a goal for both experimental and theoretical physical chemists since the 1930s. This is because the transition state governs how chemical bonds form and break during a chemical reaction. The transition state is a very short-lived complex, only a few femtoseconds, billions of billionths of seconds.
“In order to control a chemical reaction, you have to understand how it proceeds through the transition state,” said Guo. “You have to design clever ways to do that.”
Guo’s collaborators at Berkeley first make a stable anion. It happens that these negative ions typically have a geometry that is very close to the transition state of the corresponding neutral reactions, as shown in the figure, scientists can start out with this anion and strip the electron away from these molecules using a laser light.