Isomers: New way to generate energy

[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.

[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.

[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.)

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

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.

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?

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.