We have already seen that magnetic fields can play a critical role in a discharge, trapping
the plasma and creating secondary discharges.
The ways in which magnetic fields can affect chemical reactions have long been the subject
of investigation.
Let's examine 2 different studies.
In the first scientists have discovered not only that magnetic fields can have a profound
impact on the ability of an atom to attract to itself an electron pair with another atom
in a chemical bond but also on the hardness of the element.
In the second they were able to make changes to the phase of the wavefunction of the atoms
and molecules when they collide using magnetic fields which allowed them to alter the outcome
of a chemical reaction.
The exotic behaviour of chemical systems under the influence of strong magnetic fields has
long been of interest to chemists and physicists.
In the first study, they calculated the ionisation energies and electron affinities for main
group atoms from hydrogen to krypton in magnetic fields as high as 235,000 Tesla.
For comparison, Earth's magnetic field is just 0.00003 Tesla.
They used this to work out the hardness and as well as electronegativity, which is how
easily an atom can attract a bonding pair of electrons.
This enabled them to construct an alternative periodic table.
This revealed patterns that deviated widely from those expected under no external magnetic
field.
The most surprising observation from this work was how complicated the pattern of ionisation
energies, electron affinities and consequently electronegativity and hardness, turned out
to be with increasing magnetic fields.
This they believe was due to the atoms responding to the magnetic field by altering their ground
state.
Electrons are added or removed from different orbitals with varying energies.
They hope that these findings will allow them to predict chemical bonding behaviour under
the influence of magnetic fields.
An example of this is the changes in electronegativity of hydrogen and fluorine atoms as a function
of the magnetic field suggests that at a critical field strength the polarity of the bond should
reverse.
Performing calculations on this molecule supports this prediction - the dipole moment does indeed
change direction as the field strength increases.
Such predicts could then be applied to stellar objects where typical field strengths exist
similar to these magnetic field strengths.
One word of caution though is that this is all based on calculations and not experimental
evidence.
The electronegativity and the hardness are defined as the first and second derivatives
of the energy with respect to the number of electrons at a constant external potential.
If you vary the magnetic field strength, you are varying the external potential thereby
breaking the definition of both.
In a related piece of research physicists at the MIT-Harvard Centre for Ultracold atoms
have developed a new approach to control the outcome of chemical reactions.
This is normally done by controlling the temperature, using a catalyst or with external fields such
as magnetic, electric or laser beams.
In this research, they used minute changes in a magnetic field to make subtle changes
to the quantum mechanical wavefunction of the colliding particles during the reaction.
They were able to steer the reactions into creating a different outcome.
Effectively enhancing or suppressing reactions.
They used a mixture of sodium atoms and diatomic sodium-lithium molecules at an ultracold temperature.
They aligned all the magnetic moments of the electrons using strong magnetic fields.
They then observed the chemical reactions through the decay of the number of remaining
molecules.
When they then varied the magnetic field they saw dramatic changes in the rate of reactive
scattering in a way that had not been observed before.
The reaction rate changed due to a resonance between the two quantum states of the colliding
particles.
The key elements are changes to the phase of the wavefunction of the atoms and molecules
when they collide.
These types of collisions can involve multiple bounces back and forth.
Quantum interference occurs between the effects of these bounces.
These can be constructive or destructive and thereby enhance or suppress reactions by a
factor of as much as 100.
Right now they are studying simple systems.
A diatomic molecule and an atom as larger molecules would be much more difficult to
control and describe.
The long-term goal of the research is to improve the understanding of how chemical processes
can be controlled in more general systems and environments.
Both of these studies raise the question of how much we really understand about the reactions
that occur in the magnetic field of stars and other exotic objects out in the depth
of the cosmos!