Nuclear spin conversion in polyatomic molecules
P. L. Chapovsky, L. J. F. Hermans
Abstract
Except for ortho- and para-H2, very little is known about nuclear spin isomers (or spin modifications) of molecules. The main reason is the lack of practical enrichment techniques. Recently a few enrichment methods were developed, which opened up new possibilities in the field. These methods are briefly reviewed. Substantial progress in the field has been made by the introduction of Light-Induced Drift as a gas-phase separation tool. This is illustrated by extensive data on CH3F, which reveal that the gas-phase ortho-para conversion is governed by intramolecular mixing of the nuclear spin states. The role of ``direct'' ortho-para transitions is shown to be small. Various aspects of the conversion were investigated in detail: pressure and collision partner dependence, isotope effect, temperature dependence. The most decisive information on the spin conversion mechanism is derived from the observation of level-crossing resonances in an electric field and the Quantum Zeno effect induced by collisions.
Create a lesson
Related papers
Molecular Geometry Understanding Has Unintendedly Emerged in Frontier Large Language Models
Gregorii A. Semakin, Timofey V. Losev, Ilya V. Prolomov et al.
Truncated automatic sparse differentiation for machine learning interatomic potentials
Marcel F. Langer, Adrian Hill, Michele Ceriotti
Collective Ion Dynamics from Finite-Volume Fluctuations in Model Explicit-Solvent Electrolytes
Jeongmin Kim
FOSY: Segmental Backbone Assignment in Intrinsically Disordered Proteins
Dmitry M. Lesovoy, Tatiana Agback, Panagiota S. Georgoulia et al.
Efficient tensorized evaluation of permutation invariant polynomials for representing potential energy surfaces
Junhong Li, Kaisheng Song, Hua Guo et al.
DFT GGA based datasets for H2O potential energy surfaces, permanent moment and polarizability tensors
Anoop Ajaya Kumar Nair, Elvar Örn Jónsson