First experimental proof of a chemical reaction theory predicted by quantum mechanics - School of Science, the University of Tokyo
Nov 27, 2017

First experimental proof of a chemical reaction theory predicted by quantum mechanics

 

Overview of the press release

A research group led by Professor Eiichi Nakamura, Associate Professor Koji Harano, and Professor Kaoru Yamanouchi has observed a chemical reaction of individual molecules that occurs stochastically using an atomic-resolution electron microscope, revealing for the first time that the reaction behavior conforms to the predictions of quantum mechanical theory.

The famous double-slit experiment demonstrates the quantum nature of electrons. Each electron behaves randomly as a particle, but also shows wave behavior. Although reactions of molecules have been predicted to behave similarly, there has been no proof for this prediction because of the lack of an appropriate experimental method. In the current study, Nakamura and his colleagues demonstrated the prediction of quantum mechanical transition state theory that seemingly random chemical reactions statistically follow a rule of quantum mechanical theory. They monitored dimerization reactions of [60]fullerene molecules aligned in single-walled carbon nanotubes one by one using an atomic-resolution electron microscope at various temperatures and integrated the reaction counts for several tens of molecules. This groundbreaking experimental approach provided direct proof that the ensemble behavior of random events conforms to the Rice–Ramsperger–Kassel–Marcus (RRKM) theory, a fundamental theory about chemical reactions based on quantum mechanics.

Chemical reaction kinetics have been studied since the 19th century by tracking the increase or decrease in the total number of molecules in the reaction vessel in the order of Avogadro’s number (1023) (bulk experiments). This new microscopic approach to studying chemical kinetics by observing reaction events of tens of molecules enables us to obtain information on the atomic-level motions of molecules and hence to discover new chemical reactions, and to design rational chemical reaction processes.

 

Figure 1. Direct microscopic observation of individual reaction events – The first experimental proof of first-order reaction kinetics of unimolecular reactions predicted by quantum mechanics.

 

Publication details

Journal Journal of the American Chemical Society
Title Direct Microscopic Analysis of Individual C60 Dimerization Events: Kinetics and Mechanisms
Authors Satoshi Okada, Satori Kowashi, Luca Schweighauser, Kaoru Yamanouchi, Koji Harano,* Eiichi Nakamura*
DOI 10.1021/jacs.7b09776
Paper link http://pubs.acs.org/doi/10.1021/jacs.7b09776

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