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[gizz72]

Greetings,

Isomers a 'revolutionary' way to generate energy.
http://www.rnw.nl/hotspots/html/iso031024.html

But in the hands of the Russians it's another story?
http://www.abc.net.au/news/newsitems/200411/s1245917.htm
:-o

-edit-
ChinaDialy:

Earlier this year, a senior Defense Ministry official was quoted as telling news agencies that Russia had developed a weapon that could make the United States' proposed missile-defense system useless. Details were not given, but military analysts said the claimed new weapon could be a hypersonic cruise missile or maneuverable ballistic missile warheads.

This looks really bad. :-( Russia is upgrading their weapons, by 2005 they'll have one operational.

-/edit-

Regards,

Gizz

[Cymric]

Ah, the 'graser'. I must say that while I'm not against the idea of isomer triggering, I agree with the sceptics for now. Proving the principle is one thing, building a military device around it quite another. Then again, we shouldn't be underestimating the Russians either. They are very strong in theoretical matters, and while they may not have the money for the latest and top-notch equipment, the combination can still produce very clever and very deadly designs.

However, the advent of new weapons does not really bother me. Of course, it's a complete waste of time and money apart from the scientific effort, but that is the case with any military device. Ordinary cruise missiles are now able to hit me within a meter of where I currently sit. Their precision is the frightening part, not the charge they're carrying because to me, the end result won't matter. I will still be dead.

[PMC]

[dumb mode]

Would someone explain to me (in words of one syllable) what Isomer triggering actually is?

[/dumb mode]

[Cymric]

Err. I. no. can. do. in. sim-ple. words. But I can try to do it in slightly more complex ones :-).

All fundamental particles have a property known as spin. Spin is basically the way such a particle revolves on its axis, although you have to keep in mind that this view is a macroscopic analogue, and thus can only be taken so far before quantummechanical weirdness steps in. However, for the purposes of this discussion, it will do fine. It turns out that a bunch of protons, neutrons and electrons are happiest, i.e., have the lowest energy, when all spins are parallel. In other words, the particles are revolving in the same direction. Now imagine that we supply them with some energy. That can cause the spins to lose alignment and become anti-parallel. This so-called excited state is unstable: the system tries to lose the excess energy by radiating it away. That radiation can take on many forms: it can be X-rays, it can be ordinary light, it can be heat.

In case of electrons, such loss of energy is quick and in almost all cases, practically instantaneous. Exceptions are when we are dealing with systems in vacuum (like outer space) or phosphoresence, which can last for several hours. In an atomic nucleus, it is much more difficult to get rid of the energy, as a nucleus is a rather 'fluid' entity. There is much more interaction between protons and neutrons, and that tends to stabilise matters. Sometimes to such a degree that a nucleus might exist for millions of years in its excited state before it finally radiates away the energy. Since these excited nuclei have different properties from the unexcited one, they are referred to as isomers: same mass, different properties. Such a name does not exist for excited electrons: they lose their energy too quickly.

What is interesting about this nuclear reorganization is that much more energy is liberated. The radiation therefore appears as gamma rays, which are much more damaging than the already potent and dangerous X-rays.

Now we finally come to 'isomeric triggering': you take a clump of atoms (usually a metal) in which the nuclei are known to be in their excited state. You bombard them with low energy radiation---usually X-rays---and hope that this pulse will be the tiny push the atom needs in order to flip its nuclear spins back in line, and thus produce the desired gamma radiation. In other words, you try to influence or even control the process of normal decay. Needless to say, generating strong beams of gamma radiation at will can be a pretty powerful weapon. It can also be a very effective source of radiation in nuclear medicine: you just seed a tumor with tiny clumps of the material, X-ray them gently, and the tumor is killed effectively without the healthy surrounding tissue being affected too much.

Isomeric triggering has been demonstrated in the lab, resulting in a tiny extra energy output (I think about 2.5% extra compared to what went in). Some people claim to have measured much, more stronger energy production, but verfication of such numbers is a) hard, as you need very specialised equipment, and b) in most cases, very confidential, as the military doesn't want this technique to fall into enemy hands. That's why I don't think it is wise to underestimate the Russians: some physicists have labelled the theory as sketchy, but the Russians have demonstrated far too often that they can be frighteningly clever if they have to.

I think that covers the essential bits.

[Karlos]

It's a bit like the nuclear analogue of a chemical mixture which is thermodynamically unstable but kinetically stable.

The excited nuclear state is thermodynamically unstable with respect to it's lower energy ground state, but it has to overcome various strong internal interactions in order to reconfigure. The irradiation gives it the boost it needs to overcome the initial barrier.

In a similar way, a mixture of hydrogen and oxygen is extremely thermodynamically unstable - it would be a much lower energy configuration as water. However, it will sit around indefinately because energy is required to break up the existing molecules such that they can recombine. It doesn't yet have the energy it needs to overcome this - it's kinetically stable.

Now, throw a spark in there and watch it go...

[bloodline]

Karlos wrote:
It's a bit like the nuclear analogue of a chemical mixture which is thermodynamically unstable but kinetically stable.

The excited nuclear state is thermodynamically unstable with respect to it's lower energy ground state, but it has to overcome various strong internal interactions in order to reconfigure. The irradiation gives it the boost it needs to overcome the initial barrier.

In a similar way, a mixture of hydrogen and oxygen is extremely thermodynamically unstable - it would be a much lower energy configuration as water. However, it will sit around indefinately because energy is required to break up the existing molecules such that they can recombine. It doesn't yet have the energy it needs to overcome this - it's kinetically stable.

Now, throw a spark in there and watch it go...

Or even a catalyst... oh the fun we had with platinum :-D

[Karlos]

Agreed - catalysts can be a lot of fun ;-)

A catalyst typically provides a lower energy path for the reaction so you don't need to inject as much energy - or indeed any if the catalysed path provides such a lower path that there is already enough thermal energy in the system to set it off.

I think in this case that the X Ray irradiation is behaving more like the spark in your H2/O2 mix than a lump of platinum.

[PMC]

Cymric wrote:
Err. I. no. can. do. in. sim-ple. words. But I can try to do it in slightly more complex ones :-).

Haha! Will try to do my best to keep up...

All fundamental particles have a property known as spin. Spin is basically the way such a particle revolves on its axis, although you have to keep in mind that this view is a macroscopic analogue, and thus can only be taken so far before quantummechanical weirdness steps in.

Was doing fine until I stumbled across quantimmechanical weirdness... Seriously though I understand the priciple of particles revolving so far.

However, for the purposes of this discussion, it will do fine.

Am thankful for that...

It turns out that a bunch of protons, neutrons and electrons are happiest, i.e., have the lowest energy, when all spins are parallel. In other words, the particles are revolving in the same direction. Now imagine that we supply them with some energy. That can cause the spins to lose alignment and become anti-parallel. This so-called excited state is unstable: the system tries to lose the excess energy by radiating it away. That radiation can take on many forms: it can be X-rays, it can be ordinary light, it can be heat.

I see, in the case of an LED light, we supply energy which causes the structure of the filament to become excited and thus convert the energy to radiation... Hence the bright green light I see coming from the LED on my monitor. Or indeed the burst of X-ray radiation from a hospital X-ray machine.

In case of electrons, such loss of energy is quick and in almost all cases, practically instantaneous.

Swithcing off electricity supply = LED extinguishing as the source of energy exciting the molecules is removed.

Exceptions are when we are dealing with systems in vacuum (like outer space)

Because there's no conductor to aid radiation of energy?

or phosphoresence, which can last for several hours. In an atomic nucleus, it is much more difficult to get rid of the energy, as a nucleus is a rather 'fluid' entity. There is much more interaction between protons and neutrons, and that tends to stabilise matters. Sometimes to such a degree that a nucleus might exist for millions of years in its excited state before it finally radiates away the energy.

And I assume this is how radioactive metals for example remain in such a state for a substantial length of time?

Since these excited nuclei have different properties from the unexcited one, they are referred to as isomers: same mass, different properties. Such a name does not exist for excited electrons: they lose their energy too quickly.

So the large bit in the middle of the atom (nucleus) will react differently when in it's energized state to the smaller bits that go round the big bit (neutrons, electrons)?

Please excuse my use of language, I'm trying to break it down so I understand it and my fellow intellectually challenged can keep up!

What is interesting about this nuclear reorganization is that much more energy is liberated. The radiation therefore appears as gamma rays, which are much more damaging than the already potent and dangerous X-rays.

Ah! With you now! So Gamma Ray radiation is the result of a different process than other forms of radiation (x ray, infrared, heat)? I am aware that Gamma ray radiation is both difficult to shield against and causes damage to our DNA.

Now we finally come to 'isomeric triggering': you take a clump of atoms (usually a metal) in which the nuclei are known to be in their excited state. You bombard them with low energy radiation---usually X-rays---and hope that this pulse will be the tiny push the atom needs in order to flip its nuclear spins back in line, and thus produce the desired gamma radiation. In other words, you try to influence or even control the process of normal decay.

...usually in a metal? As in a piece of radiactive material? You bombard it with x ray radiation and the material suddenly (or over a certain amount of time) 'flips' to a stable state and sheds a large burst of gamma ray radiation? So you can influence the material to emit a pre-calculated burst of said gamma rays?

Needless to say, generating strong beams of gamma radiation at will can be a pretty powerful weapon. It can also be a very effective source of radiation in nuclear medicine: you just seed a tumor with tiny clumps of the material, X-ray them gently, and the tumor is killed effectively without the healthy surrounding tissue being affected too much.

So the gamma ray burst may be focused in some fashion? Is this the concept of a gamma ray beam?

[bloodline]

PMC wrote:

I see, in the case of an LED light, we supply energy which causes the structure of the filament to become excited and thus convert the energy to radiation... Hence the bright green light I see coming from the LED on my monitor. Or indeed the burst of X-ray radiation from a hospital X-ray machine.

Actually LED's are a special case (and they don't use a filament), when you excite an Atom, or a molecule you cause some electrons to be promoted to a higher electronic... err... orbital, and then when the electon "falls" back to it's ground state it releases the same amount of enegy that promoted it... but the electrong doesn't always fall straight to the ground state, but through intermediate states releasign smaller amounts as it goes.

[Cymric]

PMC wrote:
I see, in the case of an LED light, we supply energy which causes the structure of the filament to become excited and thus convert the energy to radiation... Hence the bright green light I see coming from the LED on my monitor. Or indeed the burst of X-ray radiation from a hospital X-ray machine.

Not entirely. Electrons have other ways of temporarily 'storing' the energy you supply, and changing spin state is just one of them. They can for example increase their distance to the nucleus: as Bloodline already cryptically stated, move to a higher orbital. X-rays are in a different category alltogether, as they are produced when an electron which is in the lowest orbital is knocked out of the atom alltogether, and the electron in the next highest orbital more or less 'falls' into the hole. There is such an energy difference between lowest and next-lowest orbital that the resulting radiation can be very damaging to ordinary living tissue. That's also why X-ray devices need a lot of oomph, read kilovolts, to produce them. (You first need to supply the energy to knock the electron out of its orbit, after all.)

Because there's no conductor to aid radiation of energy?

No. Radiation doesn't need a conductor. The problem is more subtle: sometimes the excited state needs a little 'push' to get it underway to its stable state, just as was the case with the isomer triggering. That energy is usually supplied in the form of a collision with other electrons, atoms or molecules. And in the vacuum of space, there are not a whole lot of candidates around, for obvious reasons.

And I assume this is how radioactive metals for example remain in such a state for a substantial length of time?

Amongst other things. Above I mentioned another: that little 'push'. Karlos has already mentioned the 'spark' in the hydrogen-oxygen mixture; this is similar.

So the large bit in the middle of the atom (nucleus) will react differently when in it's energized state to the smaller bits that go round the big bit (neutrons, electrons)?

The current view of an atom is as follows: you have a very tiny heavy center, where 99.99999% of all mass of an atom is located. In that center is a clump of protons and neutrons. Then, at a distance of 10.000 times the diameter of that nucleus, you will find the first electron. There is nothing in between. No air, no light, no nothing. Depending on the element you're dealing with, more electrons are in the neighbourhood, up to a distance of about 20.000 times the diameter of that tiny nucleus.

Now to answer your question: in chemical reactions, the isomer will behave a teensy, weensy bit differently, but the effect is not measurable except in case of very light and small atoms (ordinary hydrogen compared to heavy hydrogen or deuterium, for example). You need to resort to specialised nuclear reactions (firing protons or neutrons at it, for example) in order to see the difference.

Ah! With you now! So Gamma Ray radiation is the result of a different process than other forms of radiation (x ray, infrared, heat)? I am aware that Gamma ray radiation is both difficult to shield against and causes damage to our DNA.

Yes, although the basic principle---getting rid of excess energy---is the same. And gamma radiation is indeed harmful to us, much more so than X-rays.

...usually in a metal? As in a piece of radiactive material? You bombard it with x ray radiation and the material suddenly (or over a certain amount of time) 'flips' to a stable state and sheds a large burst of gamma ray radiation? So you can influence the material to emit a pre-calculated burst of said gamma rays?

Yes, yes, and yes. The reason for 'metal' is that the isomers currently under study are metals, although in theory, even a gas or non-metal would do. And the trick is to make that amount of time as short as possible, so the pulse of gamma radiation is powerful.

So the gamma ray burst may be focused in some fashion? Is this the concept of a gamma ray beam?

I don't think the resulting beam can be focussed as there is no way to control the direction in which the atom releases the energy, and to my knowledge no lenses or mirrors exist to change the direction of gamma radiation as you can do with ordinary light.

[KennyR]

Why have I never heard about this kind of isomer? :-(

To me, an isomer is a compound with the same chemical structure but a different arrangement. i.e. ispropyl alcohol is a structural isomer to propanol.

[Karlos]

@Kenny

Did you do Nuclear/Radiochemistry in any of your degree options?

Isomeric implies the same components in a different configuration. This goes for for nuclear structure too (as distinct from isotopes of course).

[KennyR]

Yes, I did. I did radiochemistry, NMR, and quantum physics, among other physical atomic theories (and they all sucked ;-)). Add on to that I'd learned a pile of stuff from just reading my own books before and outside uni. I'd still never heard of it. That's quite a new experience for me. My knowledge of physics isn't very in-depth, but there isn't many things in science that I actually have never heard of before, and this is one of them.

[Karlos]

We all live and learn. If you studied radiochemistry I would expect you to have bumped into nuclear isomers before. It's part of the shell model IIRC - that is that the protons/neutrons are arranged in concentric shells, with different overall conformations possible (especially for open outer shells), but overall the system is fluid over a long timescale. Some combinations just aren't stable in any conformation (long term) once you get a large enough nucleus and so you begin to get your radioactive nuclei...

-edit-

Perhaps your prodigious intake of knowledge has caused some older, relatively unused information to be expunged

I use that excuse all the time :-D

[blobrana]

Hum,
nothing new...

A bit like getting `free` energy from a fridge. you are just extracting the heat from excited atoms, by pumping gas around two containers.

In this case you are just tapping into the free energy from excited atomic states...in this case its not the electron spin states; its the proton spin, that store the energy and release it , by some `trigger`...so it can really should be described as a sort of battery...