X-Message-Number: 25546
From: 
Date: Fri, 14 Jan 2005 12:50:59 EST
Subject: Re: CryoNet #25498 NMR freeze

From: "leo" <>

> 
> So far I now (I could be wrong) all hydrogen protons (not atoms) are aligned 
> 
> in a magnetic field, At 1 Tesla, for every 2 million protons, there are 6 
> more protons aligned with the field than there are aligned against the 
> field, in your reasoning this 6 protons are polarized, this is not important 
> 
> for MRF freezing because the aligning of all the protons makes it possible 
> to resonate them all with a CONTINUSLY RF Field (not a microsecond pulse of 
> a MRI or NMR scan),
> 

First, here is a strong coupling between proton spin an orbital electron, so 
that if protons are polarized atoms are indeed polarized too. That is  why 
hydrogen based MRI don't work with ice: If the atoms are locked in a definite 
position, you can't "jiggle" the protons inside them.

One tesla is a big field in the lab, but it is vanishingly small against the 
local molecular field. There is no 499 999 atoms (or protons) with the spin up 
and 500 001 with the spin down, the true quantum state is 2 atoms with a 

defined macroscopic spin and 999 998 in a superposition state of up and down. 
You 
have not polarized them with the one tesla field and they don't count.

If you want high polarization rate, up to 80 percent of atoms, you have to 
use laser polarization in a gas such xenon 129 or helium 3.

Back to Hydrogen NMR: May be at some precession frequencies flipping up the 
spin continuously at near the Larmor frequency could accelerate freezing. If 

here is such an effect, each water molecule with a polarized hydrogen atom would
work as a starting point for an ice crystal. A typical ice crystal would then 
have a mass in the million of molecules range, this is very small and could 
look as glassy ice. It could be interesting for cryonics organizations to test 
this. The supercooling effect seems more dubious and in any case less 
interesting. It is known that supercooled water may turn solid if mechanicaly 

disturbed. May be the original idea was that: Supercool the water and then use 
NMR to 
freeze it in a nanocrystaline form. This seems to be a possibility.

Now, if you are convinced that this system works, why not test it yourself? 
Beware yet: Producing a magnetic induction in the tesla range is not a simple 

task. Be ready to buy some tons of cooper. I don't think this would work but if
you are convinced it does, I may let you use a technical facility here in 
France, you seem to be on the right side of the pond...

Yvan Bozzonetti.


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