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merrlin
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Spin locking of electrolytic reactions
This topic is a continuation of my earlier posts on the "reactions that emit radiation" thread. I am developing a microwave-pumped electrolytic cell
that will be used to investigate spin locking of electrolytic reactions. In contrast to conventional microwave pumping by irradiation (e.g. in ESR), I
am using a current flowing in the cathode of the electrolytic cell to produce an oscillating magnetic field at the surface of the cathode. The cathode
is part of a transmission line structure driven by a solid-state microwave current source. RF Magnetic fields with intensities greater than 10 Gauss
may be achieved at the cathode surface with currents on the order of one ampere at low voltage. In combination with an applied DC magnetic field, The
cell provides for pumping of unpaired electrons at the cathode surface and in the adjacent electrolyte. It is my assumption that an electron donated
by the cathode and a cationic species may be considered as a "quasi-radical pair." In operating the cell, a DC reduction potential is applied to an
electrolyte flowing through the cell to obtain a current associated with a reduction reaction. A DC magnetic field is applied to provide Zeeman
splitting, followed by the application of microwave current to provide magnetic pumping at the cathode surface.
My Goal is to achieve pumping of the free electrons contributed by the cathode in combination with isotope selective pumping of a cationic species so
that the quasi-radical pairs containing a particular isotope at the cathode surface are locked in a triplet state (T+, T-). During the sweep of the DC
magnetic field/RF current frequency, resonance and locking would be detected by a drop in the observed reduction current.
In 2001 Buchachenko wrote " Besides the many factors controlling nuclear spin selectivity, there are two outstanding and highly promising but not yet
properly exploited, microwave induced MIE and dimensionality." The system I am developing addresses both of these factors. I am interested in isotope
separation and selective organic synthesis, and I believe that proper selection of electrode and electrolyte materials can greatly reduce the
relaxation effects that work against efficient spin locking at a cathode surface. Although I will be starting with H2O and D2O based electrolytes, I
would like to hear from anybody who has experience with aprotic solvents or room temperature ionic liquids, and transition metal complexes.
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bquirky
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! 
sounds interesting whould an electrolyte simalar to a lithium battery be suitible ie propylene carbonate & Dimethoxyethane ?
Thats just a wild guess that sounds like a spectacularly complex experiment !
How do you measure the electron spin or know that its working as you expected ?
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hissingnoise
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Most here merrlin are interested in the applications of electrochemistry rather than the cutting-edge nitty-gritty. . .
You would seem to have more to teach than to learn.
Pictures of cell(s) you're working on would be welcome. . .
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Mr. Wizard
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It sounds like a bunch of bull to me. Is it some kind of contest to stack as many eclectic exotic phrases together and see how many people will
swallow it? I was checking the posting date, looking for April 1 
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hissingnoise
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If it is just an exercise in urine-extraction, it's a fairly sophisticated one!
I'm waiting for the shots!
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merrlin
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Quote: Originally posted by Mr. Wizard  | | It sounds like a bunch of bull to me. Is it some kind of contest to stack as many eclectic exotic phrases together and see how many people will
swallow it? I was checking the posting date, looking for April 1
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Have you read Buchachenko's book or any of the papers I posted?
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merrlin
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Attached are the following files:
system_diagram.pdf--This file shows an overview of the system. RF components can be obtained from Mini-Circuits, data acquisition modules from
Measurement Computing, circuit boards produced by AP circuits, and the ICs and passives can be obtained from Digi-Key. Not including the PC, The
system comes in at around $5000.
60w__1di-1g_pfa_280Mhz_400-30.asc--This file is the LTSpice simulation file for the electrolytic cell and microwave driver. If you download LTSpice
you can tweak it and observe the results. The transmission line section is .4 inches long, and uses the distributed parameters obtained from the E-M
model. LTSpice is an excellent version of PSpice that can be downloaded from Linear Technology. Their 1084 series voltage regulators and LT1210 op amp
will be used to control the DC magnetic field sweep and provide a stable 5V for instrumentation power.
I have been working on this for a couple of years and a considerable part of my time has been spent trying to find out if anybody has done this before
or whether there is a reason it wouldn't work. The brief correspondence I have had with academic experts leads me to believe that it is novel and
cannot be rejected out of hand on a theoretical basis. I have been advised to take a combinatorial approach. There are literally millions of
electrolyte compositions that can be run through the system, and I am trying to learn which would be the best to start with.
I have tried to attach some graphics files (.png), but they are being ignored.
Attachment: system_diagram.pdf (28kB)
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Attachment: 60w__1di-1g_pfa_280Mhz_400-30.asc (19kB)
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merrlin
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I've been able to attach graphics files by changing the .png extension to ".pngfile." Hopefully they will be downloadable and visible after editing
the extension back to ".png."
E_cell_2D_E-M_model_structure.pngfile--This file shows a 2D cross section of the cell. The model employs symmetry to reduce node count and
computational load. Supporting structure is FR4 glass-epoxy. Sea water is the electrolyte. A .001"T x .060"W (.030"half width shown) cathode is shown
above .001" x .300" ground plane, separated by .001" PFA dielectric film and .001" electrolyte gap.
E_cell_2D_E-M_model_flux-density_overall.pngfile--This file shows the overall magnetic flux density plotted for a cathode excitation current of 2
amperes at 280MHz. The structure model has the following distributed characteristics: 80n H/m, 4.78 W/m (2.39 ohms/m), and 755 pF/m.
E_cell_2D_E-M_model_flux-density_closeup.pngfile--The magnetic flux in the gap is about 1.4 millitesla (14 Gauss).
LTSpice_plot.pngfile--This plot shows the input current I(R1) and the magnetic pumping current I(R63).
Attachment: E_cell_2D_E-M_model_structure.pngfile (7kB)
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Attachment: E_cell_2D_E-M_model_flux-density_overall.pngfile (8kB)
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Attachment: E_cell_2D_E-M_model_flux-density_closeup.pngfile (8kB)
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Attachment: LTSpice_plot.pngfile (21kB)
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merrlin
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| Quote: Originally posted by bquirky | !
sounds interesting whould an electrolyte simalar to a lithium battery be suitible ie propylene carbonate & Dimethoxyethane ?
Thats just a wild guess that sounds like a spectacularly complex experiment !
How do you measure the electron spin or know that its working as you expected ? |
Propylene carbonate would be a good candidate due to its voltage window. Since the cell electrolyte gap is on the order of a few mils, do you know if
viscosity would be a concern? Since the electrolyte is pumped through the cell, much of the apparent conductivity of the electrolyte solution will be
due to bulk transport as opposed to diffusion.
After the electrolyte is flowing in the cell and the applied DC potential produces an observable current associated with a reduction reaction, the RF
current is applied to produce the high frequency magnetic field. The DC magnetic field is then swept over a range of values. If resonance occurs and
spin locking is achieved, a drop in the reduction current would be expected. The reduction current for a .06" by .400" electrode is expected to be on
the order of .1 to 1 milliampere. Spins would not have to be measured, and a sweep could be done in less than a minute for a particular RF frequency
and amplitude. Once resonant conditions have been established for a particular cation (e.g., iron) the cell could be run to collect the reduction
reaction product. Mass spectrometry of the product or electrolyte solution would then be used to determine which isotope(s) had been locked.
Two electrons with the same spin cannot share the same orbital. If an unpaired electron and an electron donated by the cathode have the same spin,
reduction of the cation cannot be completed. The object is to pump the electrons under resonant conditions so that they have the same spin. The good
news is that very little energy is required to move an electron between magnetic energy levels. The bad news is that the small fields generated by the
movement of species in the electrolyte and hyperfine coupling with other spins lead to spin-lattice and spin-spin relaxation. The goal is to provide
pumping at sufficient amplitude and frequency to overcome relaxation effects. Relaxation effects can also be reduced by electrolyte component
selection.
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merrlin
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| Quote: Originally posted by hissingnoise | Most here merrlin are interested in the applications of electrochemistry rather than the cutting-edge nitty-gritty. . .
You would seem to have more to teach than to learn.
Pictures of cell(s) you're working on would be welcome. . .
|
The applications I am pursuing are isotope separation and organic synthesis. An industrially useful system would probably require thousands of cells,
but I think that in those quantities the cells could be constructed for less than $100 each.
Having worked on various missile programs, I am familiar with microwave circuits and specifications for electroplating (my background is materials
science), but I have very little hands-on experience with electrochemistry. My experience is pretty much limited to electropolishing and a little bit
of copper plating.
I hope you are able download the .png files. As stated in an earlier post, I am just finishing the design phase. The electrolytic cell is basically a
shorted transmission line that is masked so that part of the top conductor facing the ground plane is exposed to a flowing electrolyte. The concept is
straightforward but there is a lot involved in optimization. In keeping with the philosophy of "measure twice, cut once," I have spent a lot of time
on design and analysis. I considered designing and building the RF amplifier, but decided to buy the components instead. The microwave world is
focused on delivering maximum power to a matched load. In this system, the goal is to develop a current with minimum power input. A good EE/technician
could probably cannibalize a cell phone to produce a driver for a smaller version of this cell.
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Mr. Wizard
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The more I read, the more it sounds like horse feathers.
"A good EE/technician could probably cannibalize a cell phone to produce a driver for a smaller version of this cell." Would you hook the cellphone to
some solar powered yard lights?
Bafflegab Bullshit.
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FrankRizzo
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Mr.Wizard,
You *do* realize that cell phones use microwave frequency transmission circuits, right?
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merrlin
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| Quote: Originally posted by Mr. Wizard | The more I read, the more it sounds like horse feathers.
"A good EE/technician could probably cannibalize a cell phone to produce a driver for a smaller version of this cell." Would you hook the cellphone to
some solar powered yard lights?
Bafflegab Bullshit. |
It isn't how much you read, it's how much you comprehend. So I'll rephrase the question:
How much of Buchachenko's book and the journal articles I posted do you understand? Do you understand the circuit I posted?
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Mr. Wizard
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No, why don't you explain it for me? Why would somebody bother with a cell phone when you can get real watts out of a microwave oven? Oh wait, I know;
you can set the transmission frequency by punching in the secret numbers available at certain sites on the internet, and you can pack the phone in
dry ice to keep it from overheating when the SWR and impedance mismatchs between the dilithium crystals and the beer can wave guide you made. Is
there some special benefit to the 1.8 GHZ compared to 2.4 GHz or are you using a 900 MHz one?
If only I was smart enough to pick up on the secrets that are being scattered in front of me, and read all the very complicated papers that are shown
in all the links. Where did I put the link for the mono-atomic magnetic spin
stabilized hydrogen rocket fuel with the nickel 1/4 wave matrix stabilizer and doppler damper?
Seriously, I think somebody is blowing smoke here. Am I the only one not biting on this?
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Sedit
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Nope not the only one not hungry for the bait, Im on the edge though. It seems as though he knows what hes talking about but that can with ease make
someone that dont know WTF hes talking about say.."um... OK sure..". Tell us a bit about your self, your company..merits ect..
If you could dumb it down for us as simple as possible that could quite easly help matters. To me it basicly sounds as though your trying to do basic
electrolysis with AC current overlay such as used in some cells to improve yeilds or cause reactions that would happen otherwise. Just in this case it
seems ultrahigh frequencys are being used. Although if thats the goal it all seems a little over the top.
Dumb it down and explain to us laymen terms because if one isn't able to do that either there full of shit or they succeed and no one in the general
public cares because they see no use in the overly complicated equipment. Just a thought.
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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FrankRizzo
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| Quote: Originally posted by merrlin | | Quote: Originally posted by Mr. Wizard | The more I read, the more it sounds like horse feathers.
"A good EE/technician could probably cannibalize a cell phone to produce a driver for a smaller version of this cell." Would you hook the cellphone to
some solar powered yard lights?
Bafflegab Bullshit. |
It isn't how much you read, it's how much you comprehend. So I'll rephrase the question:
How much of Buchachenko's book and the journal articles I posted do you understand? Do you understand the circuit I posted?
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He doesn't need to read or comprehend the articles or schematic because somehow he's already made up his mind that you're a fool. I guess he doesn't
realize that people rarely take the time to make a post unless they think their ideas have merit, or they're trolling You don't seem to be doing the
later.
How did you first come across the effect in question? Is this a thought experiment come to the physical experiment state, or did you notice some
anomalous effect in another project? I'm interested, please continue posting.
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merrlin
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| Quote: Originally posted by Sedit | Nope not the only one not hungry for the bait, Im on the edge though. It seems as though he knows what hes talking about but that can with ease make
someone that dont know WTF hes talking about say.."um... OK sure..". Tell us a bit about your self, your company..merits ect..
If you could dumb it down for us as simple as possible that could quite easly help matters. To me it basicly sounds as though your trying to do basic
electrolysis with AC current overlay such as used in some cells to improve yeilds or cause reactions that would happen otherwise. Just in this case it
seems ultrahigh frequencys are being used. Although if thats the goal it all seems a little over the top.
Dumb it down and explain to us laymen terms because if one isn't able to do that either there full of shit or they succeed and no one in the general
public cares because they see no use in the overly complicated equipment. Just a thought. |
I'll give it a shot, but I am going to have to ask you to read the section 2. "The Radical Pair Mechanism" in the file "A study in Spin
Chemistry.pdf." I've been studying this stuff for 2 1/2 years and it isn't easy. The key here is that reaction between radicals in a radical pair in
a triplet state is forbidden. One of the mechanisms that can enhance conversion of the triplet state to a reactive singlet state is hyperfine
coupling between an unpaired electron and a nucleus with a magnetic moment. Most of the experimental work that has been done has involved organic
compounds containing both carbon-12 and carbon-13. Since carbon-13 has a magnetic moment and carbon-12 does not, carbon-13 containing radical pairs
will have a slightly higher probability of recombining without diffusing apart. This provides a basis for isotope selective reactions.
Consider two identical chemical ions or radicals that differ only in their isotopic composition. One has a magnetic nucleus (e.g. carbon-13) and the
other does not (e.g. carbon-12). The hyperfine coupling between the magnetic nucleus and the surrounding electrons changes the available energy levels
and thus the energy differences between levels. The differences provide the possibility of selective pumping. The differences between energy levels
correspond to resonant frequencies. Nuclear Magnetic Resonance and Electron Spin Resonance both use applied DC magnetic fields to split energy levels,
followed by the applications of high frequency radiation to determine resonant frequencies. NMR operates at lower frequencies than ESR because the
differences in energy levels are smaller. For an electron, the resonant frequency has a proportionality of about 28MHz per mT of applied DC field.
Most ESR work is done at X-Band or other bands where the equipment is readily available, not because there is anything special about a particular
frequency. Although ESR at higher frequencies can provide more detailed information, ESR has also been used at around 250MHz. I've chosen to start at
280MHz and a DC field of about 10millitesla. Lower frequencies are easier in terms of dealing with skin depth losses and standing waves. If Mr. Wizard
had bothered to look at the circuit model he would have noticed that the current in the resistor at the shorted end of the transmission line is only
slightly greater than the current in the resistor closest to the source. The electrical length of the transmission line is much shorter than a 1/4
wavelength and I don't anticipate standing wave problems until operating at about 1.5GHz. At these frequencies the cell doesn't have to be treated as
a distributed circuit. Since the transmission line is shorted and doesn't have to be connected to the anode, there is only a very small high frequency
current flowing through the electrolyte. The high frequency current is simply there to provide the magnetic field that is traditionally supplied by
electromagnetic radiation.
The attached paper "Control of a Chemical Reaction by Spin Manipulation of the Transient Radical Pair.pdf" describes the use of microwave radiation to
control a photolytic reaction. Notice that they are using a high power tube (1kW) and mention a maximum microwave magnetic field of about 5mT. By
running a microwave current in the transmission line geometry I have posted , a field of 1.4mT can be achieved with a power dissipation of less than a
watt in the transmssion line, albeit at a much lower frequency.
Since electrolytic reactions occur at or very near the electrode surface, a magnetic field can be confined to a small volume adjacent to the cathode
surface. If the magnetic field is produced by a current flowing in the cathode, it will have its greatest intensity were it is most desired. Since no
metal is a perfect conductor, the magnetic field will actually penetrate a finite distance into the electrode surface.
The process of electroplating involves a free electron donated by the cathode combining with a cation that has unpaired electrons. At some point in
the process, the donated electron and an unpaired electron will have to share an orbital. I consider the combination of two to be a "quasi-radical
pair." It has been well demonstrated that radical pairs are subject to spin manipulation by the application of microwave magnetic fields. The question
I seek to answer is whether electrolytic reactions can be spin manipulated. I believe they can, if you put them in a strong enough DC magnetic field
and apply an oscillating field that strong enough and fast enough to put the unpaired electrons next to the cathode into the same spin state.
I know that the structure I am building can produce locally intense microwave fields with far less power than traditional approaches. I worked on the
AMRAAM and HARM missile programs in the 1980's so I know something about microwave integrated circuits. (Mr. Wizard, I even worked with
tungsten/copper alloys!) I have also discussed my project with EE friends who are still in the microwave business and they can't see a problem with
the basic physics of my approach. The chemistry professors (two of them spin experts) have told me the approach is novel and interesting. One of them
told me not worry about theory at this point, but to try some experiments. The point is, this may not work, but it wasn't obvious to the experts why
it wouldn't. I got involved in this when I learned how expensive some isotope separation techniques are. When I learned a little about spin chemistry
and the DC and AC field required for spin manipulation, I knew that I could build a small structure that could produce fields more efficiently and
also be combined with an electrolytic cell. Ultimately, the primary source of power loss is going to be whatever switching device is used to generate
the high frequency input.
One of the attached papers that helped convince me to pursue this project has nothing to do with spin chemistry. "The isotopic effects of electron
transfer-An explanation for Fe isotope fractionation in nature.pdf" describes isotope separation during electrodeposition of iron without any
externally applied magnetic fields. It is not clear to me that the technique is independent of hydrogen generation at the cathode, but the results are
interesting. If a simple high-current electrodeposition process can produce isotope fractionation, what might happen if you give it some help?
Attachment: The isotopic effects of electron transfer-An explanation for Fe isotope fractionation in nature.pdf (355kB)
This file has been downloaded 668 times
Attachment: Control of a Chemical Reaction by Spin Manipulation of the Transient Radical Pair.pdf (353kB)
This file has been downloaded 764 times
Attachment: A study of spin chemistry.pdf (406kB)
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not_important
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Think it might have gone better had you made your first post more like this most recent one, including those background papers. Explain the concept,
then move on to how you propose to exploit it.
A lot of this is pretty recent, along with the related studies on cryptochromes, it looks as if there is active debate over it. I'll delve deeper into
those papers tomorrow.
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watson.fawkes
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| Quote: Originally posted by merrlin | | It is my assumption that an electron donated by the cathode and a cationic species may be considered as a "quasi-radical pair."
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What spin state are you trying to get the cathode-donated electron into?
If you're looking at free electrons, for example, they follow the Pauli exclusion principle with 1s electrons. For example, free electrons create
atom-sized bubbles in liquid helium. If you're looking at cathode-bound electrons, the available electron states are entirely dependent upon the
electrode material.
These kinds of basic material choices and reaction goals drive the rest of the apparatus. It's difficult to offer advice without knowing this.
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watson.fawkes
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It's real. On the
other hand, if you haven't had undergraduate quantum mechanics, it's not going to make much sense. Learn about the principal quantum numbers of the
atomic central force solutions to Schrodinger's equation. Learn how angular momentum coupling works. Understand Zeeman splitting. That's a start.
There's more after that.
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merrlin
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| Quote: Originally posted by watson.fawkes | | Quote: Originally posted by merrlin | | It is my assumption that an electron donated by the cathode and a cationic species may be considered as a "quasi-radical pair."
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What spin state are you trying to get the cathode-donated electron into?
If you're looking at free electrons, for example, they follow the Pauli exclusion principle with 1s electrons. For example, free electrons create
atom-sized bubbles in liquid helium. If you're looking at cathode-bound electrons, the available electron states are entirely dependent upon the
electrode material.
These kinds of basic material choices and reaction goals drive the rest of the apparatus. It's difficult to offer advice without knowing this.
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I have spent some time studying electrodics (Bockris' Modern Electrochemistry 2A) and I have only learned a little bit, but I've learned that an
electrode surface and the adjacent interphase is a complex place. I'm sure some of you are better mathematicians than I am, so I am going to try and
present my qualitative perspective rather than getting in the way of your assimilation of the references I provide.
As you have pointed out, a lot depends on the electrode material. Due to the desirability of low losses and the problems associated with skin depth
and proximity effects in the transmission line (flat single turn solenoid), I am going to neglect everything except highly conductive metals for the
time being. Whether one looks at electrons as particles sitting in a conduction band or as a wave function, there is a physical distance between the
electrode surface and cation that must be crossed in order for the electron to take up its place in an orbital of the cation being reduced, say cupric
(2+) ion to cuprous (1+). In the intervening distance there are typically adsorbed species on the electrode surface and electrolyte itself. I believe
that (neglecting tunneling for the moment), as an electron nears the subject cation its spin behavior is governed less by the electrode surface and
more the adsorbed species and electrolyte constituents. The collective influences on the spin of an electron are often referred to as its spin
hamiltonian. (For you mathematicians, "Spins in Chemistry" can be purchased for $11.01 at Amazon. I bought it for the title and price, but
unfortunately most of it is beyond me. ) The spin hamiltonian of an electron that is a finite difference from the electrode surface will be dominated
by the contributions of the surrounding chemical species. For example, a water molecule or a linear organic molecule bound to a gold surface by a
thiol group could be interposed between the electrode surface and the cation. At some small distance from the electrode surface I believe that the
electron is associated with a normally neutral species in the vicinity of the cation, thus effectively converting the neutral species to a transient
radical. This transient radical and cation I consider as a "quasi-radical pair."
Since the two electrons involved have different spin hamiltonians, they will typically have different spins. However, if the elements of the two spin
hamiltionians are small, and a common dominant hamiltonian element is introduced by the application of external magnetic fields, the two electrons
would have essentially the same spin. Coupling by magnetic nuclei is one of the hamiltonian elements that can be modified. By substituting D2O for H2O
and using sulfates composed mostly of 0-16 and S-32 unwanted hyperfine coupling could be reduced. Relaxation effects can be reduced by increased
viscosity and higher molecular weights. From what I have read, spin-lattice relaxation in solutions is in the microsecond to nanosecond range,
offering hope for pumping in the 100MHz to 1GHz regime. In general, I am looking for materials that will minimize unwanted hyperfine coupling and
relaxation. For example, a thin gold surface might be preferable since gold atoms have a smaller nuclear magnetic moment than copper atoms.
I can't make any predictions about the results of my investigation, but I do believe that a small flat solenoid can be used to produce oscillating
magnetic fields that are of the same magnitude or greater than those that have been shown to produce effects in chemical reactions. I also believe
that a portion of the small flat solenoid can be masked to serve as a cathode in an electrolytic cell. An exploded view of the cell I am constructing
(first parts shipped today) shows from the bottom up:
.062" FR4 base
.001" copper ground plane, could be integrated as copper-clad base
.001 PFA film--bought from McMaster-Carr with special etchant/epoxy kit
.062"cathode support with electrolyte ducts--being machined by AP Circuits
.062"chamber top
The shims for establishing the gap under the cathode and tubing connections are not shown. Anodes can be placed upstream and/or downstream. The
assembled height is less than a 1/4" so that it can be fit into the air gap of a low power homemade electromagnet. The wide area of the ground plane
can be used to support an additional dielectric sheet and input conductor trace along with a few capacitors and inductors for tuning. I hope this
gives the general idea.
Characterization and tuning of the structure and real-time current measurement will be time consuming, but a friend has loaned me a 6GHz oscilloscope
and it is amazing what you can buy off-the-shelf these days. When I told an EE friend what I was doing a couple of years ago, he told me that the cell
phone industry had what I needed. I was amazed when I saw that a 6GHz amplifier (see attached) could be had for $2.00 these days. For the system I
will be using a 20 watt amp with limited drive that can handle open and short loads since I am likely to have a few mistakes.
Operationally the idea is to initiate an electrolyte flow in the cell, apply sufficient voltage to observe a small reduction current, apply a high
frequency current to the solenoid loop, and ramp the electromagnet current. I plan to ramp the current so that the magnetic field reaches at least
150% of that required for resonance of a free electron at the selected RF frequency. If spin locking occurs, I expect to see momentary drop in the
reduction current during the scan. During the scan Zeeman splitting and resonance will occur for a lot of unpaired electrons. The question is: can the
two unpaired electrons of interest be converted to the same spin at the same time? Since conductive losses in a short copper loop are smaller than
heating losses due to irradiation of an electrolyte, I believe that this approach has something to offer as a research tool. If an industrial use can
be found, I think that the cell is cheap enough to be used in a large-scale array.
Attachment: cell_chamber_exploded.pdf (9kB)
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Attachment: GALI-84+_mini_amplifier.pdf (135kB)
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watson.fawkes
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@merrlin: You have two basic kinds of questions here. One is about equipment and another is about reactants. These are not independent. Given an
apparatus, it will only be appropriate for certain reactants. So you can either start with an apparatus and figure out what you can do with it, or
start with a selection of reactants and figure out how to build an appropriate apparatus. Given that your apparatus is in the design stage, you
haven't fully committed to which of these paths you're on. Certainly the path of least resistance, though, is going to leave you with an apparatus.
Personally, I'm more able to address the reaction. Others are better able to address the apparatus. Now you named a bunch of potential reactants but
no reaction. Please write down some candidate reactions that we can analyze specifically.
As for the reactants, I might recommend that you consider using fluoride ions in the electrolyte. Fluorine has only a single isotope in nature
(incidentally, that's one of the reasons it's used in uranium separation). It has an unpaired 2p electron, meaning it will form electronic triplets
readily. It has paired neutrons and an unpaired proton, so the nuclear spin has doublet degeneracy. In my current state of understanding, the doublets
won't interfere with the effect you're looking for much.
There are some other effects you should be aware of. In the class of non-metallic electrodes, ionic conduction is an important phenomenon. Proton (or
in your case, deuteron) conduction is the most common charge carrier (obviously), but oxygen ion conduction is also common. Proton conduction is
particularly important for fuel cells. Now fuel cell configuration is not the electrochemical configuration that you've been looking at, but you might
consider that preferential reductions of protons over deuterons in a fuel cell might be a pretty good way of making heavy water.
Another matter you hinted at but didn't address directly is that some electrochemical reactions happen with the adsorbed species themselves. In this
case the electron configuration in the metal crystal electrode is a Fermi distribution, so you're not going to see triplet behavior. What you left
unsaid is that you've got to suppress electrochemical reactions of the adsorbed species with the cathode, or least make sure that they're not
energetically favored.
You've been assuming aqueous solutions, apparently. Have you considered other solvents? You might be able to manage the adsorption layer more readily
with a different solvent. It's not even clear to me what the effect of polar vs. non-polar solvents are. Electrostatically speaking, polar species are
preferred for adsorption, but that may not be true for any particular electrode-electrolyte combination.
It seems you'll also need to consider electron mobility in your adsorbed species. If you don't have high internal mobility, you'll be much more into
the tunneling regime and your whole experiment will be harder. My first thought is that this speaks to consider aromatic solvents, since electron
mobility in the ring is quite high.
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merrlin
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@watson.fawkes: I will be starting with a copper cathode or a gold plated copper cathode. The reduction reaction may be an electrodeposition of zinc,
copper, iron or other metal from an aqueous solution. Film adhesion or continuity isn't required since the goal is to observe a change in reduction
current associated with reduction. It's possible that film formation could even be a problem since there would be a transition from a heterogeneous
deposition to a homogeneous deposition if the substrate and cation are not the same material. Another reaction that may be used is the partial
reduction and subsequent precipitation of a cation from the exit stream by an available anion such as fluoride.
In reviewing my previous post, I realize that my statement:
"However, if the elements of the two spin hamiltonians are small, and a common dominant hamiltonian element is introduced by the application of
external magnetic fields, the two electrons would have essentially the same spin."
is ambiguous. In a quantized system at any given instant, the spins are either the same or they are not. I have attached a lecture series by Professor
Nicholas Turro of Columbia University that has contributed to my understanding of spin. Table 1. on page 42 shows a vector diagram representation of
singlet, doublet and triplet states for electrons in an applied magnetic field. A pair of coupled electrons will be in a singlet state or a triplet
state, depending upon their total spin. The singlet state and the T0 state have the same energy, with the electrons having antiparallel spins (one up,
one down). The difference between the singlet state and the T0 state is a matter of phase between the two spins as they precess about the magnetic
axis provided by the applied DC magnetic field. Frequency of mixing between the T0 state and the singlet state is a function of the difference in
their precession frequencies. S0-T0 mixing depends upon the applied DC magnetic field and can be very fast (e.g., nanosecond timescale). In an
applied DC magnetic field, the T+ and T- states are separated from the T0 state by an energy gap and a change in system energy is required for
conversion to T+ or T- from T0.
Ignoring everything except the coupled electron pair and the applied DC magnetic field, there are four available states for the electron pair: S0, T0,
T+, and T-. The two electrons cannot share the same orbital if they are in the T+ or T- states. If the coupled electrons are the unpaired electrons of
a radical pair, the radical pair cannot react until spin conversion occurs. In an applied DC magnetic field, conversion between S0 and T0 states is
typically a rapid ongoing process, and conversion between T0 and T+,T- can be induced by microwave pumping. Under ideal microwave pumping conditions,
S0 -> T0 followed by induced T0 -> T+ and T0 -> T- will halt the reaction entirely. This is why Buchachenko repeatedly refers to
"purification" as the theoretical upper limit on the separation factor for the microwave induced magnetic isotope effect (MIMIE). Isotope separation
by centrifuge or diffusion rely on the mass isotope effect that is limited by the difference in mass of the isotopes or the compounds they are a part
of and thus require a cascade system to produce a useful amount of separation. With MIMIE, a single reactor could in theory exhibit a much high
separation factor.
At what point in an electrolytic reduction reaction can the cathode donated electron and an unpaired cation electron be considered a coupled electron
pair? I don't know the answer to this, but I believe that if the applied DC magnetic field and the microwave pumping intensity are large enough and
the other magnetic influences are minimized, that spin correlation could be achieved between an electron at the cathode surface and a cation that is
some distance away. Ideally, one would want to eliminate all magnetic nuclei from the electrolyte (except perhaps the cation of interest) and have an
electrode surface composed of atoms with nonmagnetic nuclei. If one uses a polar solvent that does not dissociate into species with unpaired electrons
and does not contain magnetic nuclei it would further reduce undesirable influences. I'm not sure, but I think this might be why Malcolm Forbes' group
at the University of North Carolina is working with supercritical carbon dioxide as a solvent. With regard to fluorine, the important thing is that
notwithstanding the nuclear spin state of the fluorine atom, the nucleus has a magnetic moment that can influence the spin of nearby electrons.
Broadly put, anything that has or can generate a magnetic field could influence the spin state of the coupled electron pair. Spin-orbit coupling, in
which the magnetic moment due to an electron's orbital motion couples with its intrinsic spin, may also have an influence. Even for polar molecules
that do not dissociate, rotational motion of the dipole can contribute to relaxation effects.
Pretty soon I am going to have take my best guess and simply try it. At this point I plan to use metal sulfates that can be dissolved to form an
electrolyte from which the metal can be reduced. Zinc, iron, and copper are leading candidates. Zinc and iron are attractive since fractionation by
electrodeposition has already been reported for them, and copper is attractive since it should be relatively easy to plate onto a copper cathode. I
wonder if isotopically pure copper would have enough of an improvement in electrical conductivity to make the preparation worth the effort for use in
integrated circuits.
Attachment: Turro_spin_lectures.pdf (604kB)
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[Edited on 8-4-2009 by merrlin]
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merrlin
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The first actual part arrived. The top view shows the copper clad FR4 with a .100" wide cathode trace. The board on the left shows the as received
board with solder coating that is standard with their basic service. The right hand board shows the solder removed. The bottom shows a .060" wide
cathode trace with and without solder. One trace will be selected for use and the other removed when the cell is assembled.
Attachment: cell_board.jpg_file (99kB)
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[Edited on 8-4-2009 by merrlin]
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watson.fawkes
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| Quote: Originally posted by merrlin | | With regard to fluorine, the important thing is that notwithstanding the nuclear spin state of the fluorine atom, the nucleus has a magnetic moment
that can influence the spin of nearby electrons. |
I don't know the relevant magnitude of the energies
involved. That does matter. I think I was assuming it was small, but I'm likely wrong there.
On the other hand, in a magnetic field fluorine nuclei form a spin glass that can be pumped up, eliminating most of the doublet effects. It would
require a second oscillator, but since the gyromagnetic ratio of the nucleus is fixed, and since you know what your magnetic field is, the resonant
frequency for pumping is determined.
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