Magnetic Isotope Effect in Radical Reactions: An Introduction

ISBN-13: 9783211827840 / Angielski / Miękka / 1996 / 147 str.

K. M. Salikhov; Kev M. Salikhov

Opis

In the last two decades it was demonstrated that, in addition to masses and charges, magnetic moments of nuclei are able to influence remarkably chemical reactions. This book presents the physical background (both theoretical and experimental) of the magnetic isotope effects in radical reactions in solutions. Special attention has been paid to the quantitative interpretation of the available experimental data. This book will be useful for physicists, chemists and biologists employing the isotope effect in their investigations as well as for those involved in isotope separation and isotope enrichment projects. Additionally, the magnetic isotope effect appears to be important in geochemistry and cosmochemistry. The book can be recommended for postgraduates and senior undergraduate students.

Spis treści

1 Introduction.- 1.1 Origin of magnetic isotope effect in radical reactions.- 1.2 Favourable conditions for magnetic isotope effect.- 1.3 Some specific features of magnetic isotope effect.- 1.4 What can be gained from magnetic isotope effect?.- 1.5 Basic steps in studying magnetic isotope effect.- 2 Main concepts of the theory of magnetic isotope effect.- 2.1 Macroscopic and microscopic parameters.- 2.2 Radical pairs.- 2.3 Multiplicity and reactivity of radical pairs.- 2.4 The hyperfine coupling.- 2.5 Singlet-triplet transitions in radical pairs induced by the hyperfine interaction.- 2.6 Manifestations of radical pair spin conservation rules in singlet-triplet mixing induced by the isotropic hyperfine coupling.- 2.7 Kinetic equations for radical pair recombination.- 3 Theoretical description of magnetic isotope effect in the Earth’s magnetic field.- 3.1 Radical pairs with one magnetic nucleus (isotropic hyperfine coupling).- 3.2 Radical pairs with magnetically equivalent nuclei (isotropic hyperfine coupling).- 3.3 Radical pairs with many magnetically non-equivalent nuclei (isotropic hyperfine coupling).- 3.4 Magnetic isotope effect induced by the anisotropic hyperfine interaction (paramagnetic relaxation).- 3.5 Magnetic isotope effect in reaction kinetics.- 4 Magnetic isotope effect in the presence of external magnetic fields.- 4.1 Magnetic isotope effect as affected by constant fields.- 4.1.1 Anisotropic hyperfine interaction (the so-called relaxation mechanism of singlet-triplet transitions).- 4.1.2 Isotropic hyperfine interaction.- 4.2 Resonant microwave field pumping.- 5 Experimental evidences of magnetic isotope effect.- 5.1 Enrichment of 13C in dibenzyl ketone during photolysis.- 5.1.1 Photolysis of dibenzyl ketone in homogeneous solutions.- 5.1.2 Photolysis of dibenzyl ketone in micelles.- 5.1.3 Magnetic isotope effect in photoinduced emulsion polymerization.- 5.2 Magnetic isotope effect in radiolysis of aromatic hydrocarbon solutions in alkanes.- 5.3 Magnetic isotope effect for heavy elements.- 5.4 Magnetic isotope effect for biradical reaction pathways.- 5.5 Magnetic isotope effect in reaction rates.- 5.6 Isotope enrichment by resonant microwave pumping.- 6 Some perspectives.- References.