From Introduction To Dynamic Spin Chemistry: Magnetic Field Effects On Chemical And Biochemical Reactions

6.1 Historical Introduction

In 1976, Atkins [1] wrote a short review entitled "Magnetic field effects" and described at its beginning "The study of the effect of magnetic fields on chemical reactions has long been a romping ground for charlatans". Until then, so many papers had reported having found magnetic field effects (MFEs) on chemical and biochemical reactions. Almost all of such studies, however, lacked reproducibility andor theoretical interpretation. Thus, most scientists at that time believed that ordinary magnetic fields could not exert appreciable influence on chemical and biochemical reactions. Here, ordinary magnetic fields mean those less than 2 T, which can be generated by usual permanent and electric magnets.

This view seems to be reasonable if one compares magnetic energies of molecules with those related to chemical reactions: (1) The Zeeman splitting of an electron spin at 2 T is about 2 cm ?1. (2) The Zeeman splittings of nuclear spins are much smaller than that of an electron spin, that of proton at 2 T being about 0.002 cm ?1. (3) The thermal energy at room temperature is about 200 cm ?l. (4) The activation energies for chemical reactions are usually much larger than the thermal energy. Thus, MFEs on chemical and biochemical reactions seemed to be impossible from a thermodynamic consideration, unless extraordinarily large fields were used.

The only exception to the above discussion was the MFE on the predissosiation of I 2. In 1913, Steubing discovered that the visible...

Products & Services
ESR/EPR tubes hold samples in ESR or EPR spectrometers. They are thin glass walled tubes, uniformly thick, that produce low background noise.
ESR/EPR Spectrometers
ESR/EPR Spectrometers measure the spectrum produced by the magnetic energy level transitions of electrons having a net spin and orbital angular momentum. The spectrum obtained can be used to characterize the material being analyzed.
Magnetometers are scientific instruments that measure the strength and/or direction of a magnetic field. There are two basic types: scalar and vector.
Nanomaterials have features or particle sizes in the range of 1 to 100 nm.
Thin Film Sources
Thin film sources consist of magnetrons, evaporation thermal units, ion beams and other sources that produce deposition materials (vapors or ions) in a thin film system.

Topics of Interest

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