Difference between revisions of "Fun with spins"

Revision as of 21:59, 18 June 2021

Spin in piezochemical mechanosynthesis

Intersystem_crossing:
This can lead to the problem in piezochemical mechanosynthesis that when pressing moieties together too fast to hard,
the reaction can actually lock up and slow down rather than speed up. (wiki-TODO: check details)
This is one of the listed points in: Piezochemical mechanosynthesis#Surprising facts

Spin flips in tool-tips (to create an anti-parallel bonding singlet state) can be influenced by
nearby massive atoms with high spin orbit coupling.
(wiki-TODO: find out how that is supposed to be working)

(TODO: answer questions below – eventually explain and illustrate results)
Perhaps open questions are:

• Which heavy elements to use for speeding up reactions by speeding up inter system crossing?
• Which geometries to place these atoms on the tooltips ideally? (proximity, overlap, reaction participation, orientation, ...)
• How important is this: How big is the effect and how do different reactions vary?

Related:

• Organic anorganic gemstone interface

Nanosystems (from glossary) about Inter system crossing ...

• ... and energy dissipation, 224
• ... in pi-bond torion, 231
• ... radical coupling, 215
• ... rates of, 197, 216
• ... and reaction reliability, 210
• (also noted on page 235 top)

The issue with limited abundance of the magnetically most interesting elements

Beside iron and the the transition elements around it (Ni,Co, ..)
the elements with the most interetsing magnetic properties are the ones with f-shells.
The rare earth elements, the Lanthanides.
While these are not terribly scarce (as the name "rare earths" might erroneously suggest)
they are still by no means as abundant as most of the elements at the top of the periodic table. Also going from left to right the abundances quickly drop.

So applications are better suited for catalytic purpouses where there isn't a need for large quantities.

Today (2021) rare earth elements are needed in high quantity for making large macroscale magnets in windmills.
(Setting free large quantities ultra fine of radioactive thorium rich dust in the process of mining.)
With advanced gemstone metamaterial technology nanoelectrostatically operating electromechanical converters
will be available to replace generators needing magnets that depend on large uantities of rare earth elements.
Of course other conventional non atomically precise technology solving that problem beforehand would be nice and welcome and can't be excluded.

Some other maybe interesting related trivia

Electron spins

Triplet- and singlet-oxygen:
Oxygen has as its unexcited state the triplet state with unpaired parallel electron spins
(meaning it is a stable diradical). This is quite unusual.
The excited state of oxygen is singlet oxygen with paired antiparallel spins.
Singlet oxygen is quite metastable leading to fluorescence (red colored)

Orhto- and para-helium:
Ortohelium is heliums ground state (with necessarily paired antiparallel spins).
Parahelium with unpaired parallel spins (and necessarily one electron in the 2s shell)
is surprisingly metastable (despite being excited by a whopping 19,8 eV). There is a "forbidden" state transition.
(Wikipedia: Helium atom)

Nuclear spins

A rare case where nuclear spins have a huge (physical) effect are the nuclear spin isomers of hydrogen.

Nuclear spins usually have only minor effect on physical and chemical properties.
But they are very useful for analytic (and in the future maybe computation) purposes.

Generally

Magnetism behaves deeply quantum mechanically even at quite high temperatures (meaning room temperature)
and that across size scales spanning several atoms.
This is making crude approximations harder (or impossible).

Related

• Mechanically stable electronically excited states
• Polyaromatic pigments, F-centers in gemstones, ...See: color emulation

External links

• Intersystem crossing – (de)
• Spin–orbit coupling
• Selection rule
• Spin-forbidden reactions
• Spin crossover
• Fermi's golden rule – for transition rates

• Crystal field theory
• Jahn–Teller effect
• Optical effects

• Magnetic refrigeration – Magnetocaloric effect – (Related: Entropomechanical converter)
• (drifting off-topic: the corresponding Electrocaloric effect)