Nuclear spin isomers of molecules
by Prof. Pavel L. Chapovsky
at Quantum optics seminar
Wed, 02 Jun 2021, 15:00
Zoom link: https://us02web.zoom.us/j/84970544725
Nuclear spin isomers of molecules are the most stable quantum states in molecules determined by symmetry of wave functions of identical nuclei in the molecule, bosons or fermions. Spin isomers exist in diatomic molecules, e.g., H2 (2 types of isomers, ortho- and parahydrogen); symmetrical tops, e.g., CH3F (2 types of isomers); asymmetric tops, e.g., C2H4 (4 types of isomers). Nuclear spin isomers have important applications in molecular spectroscopy, NMR, and astrophysics. For most applications of isomers their stability and conversion mechanism are very important.
Depending on physical conditions, numerous processes can perform conversion of spin isomers. Interesting physical situation appears if molecular environment cannot change spin isomer state directly being “nonmagnetic”. In this situation, isomer conversion is extremely slow, but occurs, nevertheless, by a specific process, quantum relaxation. It is based on the quantum mixing of the spin isomers by intramolecular hyperfine interactions and interruption of this mixing by molecular collisions. Investigation of the isomer conversion and isomer applications rely on the methods of spin isomer enrichment. This is difficult problem because of almost identical physical properties of different nuclear spin isomers of molecules.
We will review in this presentation the following points:
• Determination and discovery of nuclear spin isomers
• Enrichment of nuclear spin isomers
• Quantum relaxation of nuclear spin isomers
• Nuclear spin isomers in astrophysics at low temperatures
• Our present project on spin isomers of polyatomic molecules
Created on 30-05-2021 by Folman, Ron (folman)
Updaded on 30-05-2021 by Folman, Ron (folman)