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. Content-Type: text/html; charset="US-ASCII" [ AUTOMATICALLY SKIPPING HTML ENCODING! ] Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=25546