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.
