chemoleo - 19-2-2004 at 12:22
Today I had an interesting conversation with a fellow mad scientist.
We were discussing nuclear and electron spins, and such.
Now, I was making the point that any energy a system liberates is (if not transverse, rotational or vibrational motion) via the emission of photons -
of any wavelength, or electric/magnetic fields. Hold on, before you bark up 
- We
all know that a system absorbs energy when it absorbs electromagnetic radiation (light). Conversely, if you shed energy, electrons move down via
orbital transitions and thereby produce photons... right? The energy of the photon (or the frequency) relates to the energy gap between the exited and
ground state, and the energy is correlated to frequency via E = hv.
Now the question is this - what happens if I take a large number of atoms, strip them off their electrons, and irradiate them with photons? For
example, I could ionise hydrogen, deuterium or helium, so that no electrons are present, and capture those protons/ D+/He2+ in a magnetic trap. What
would happen now if I bombarded the protons with X-rays, or gamma rays?
Without the electrons, there is no such thing as an excited state, right? Would that mean, those protons would be NON-ABSORPTIVE? I.e., would that
mean that protons would be a 'supercompound' that would transmit any type of radiation, at any density, at any frequency, and absorb neither
heat, nor light of any form? I can only wonder at the applications if this is true...
The discussion went on further as to what energy really is. I.e. Kinetic energy (translational) is really meaningless until it hits a reference
compound, at a different velocity vector. Then it sheds energy... again as photons, and electric/magnetic fields. Then, what are photons? or the
fields it is composed of? Where does the energy lie in ?
PS It's very dangerous to get confused here about energy and forces - i.e. there are the forces holding together nuclei, then gravitation, then
electric/magnetic fields.... whats the difference to energy here? Lol how little I (we?) know 
PS2 I am aware of nuclear spins (in an electronless atom) still absorbs energy, such as in magnetic fields. Somehow I doubt this would be a mechanism
of absorption of gamma rays though... but then, dont gamma rays have EXACTLY this effect that they interact with the nuclei? How about protons?
[Edited on 19-2-2004 by chemoleo]
guaguanco - 19-2-2004 at 13:10
What is energy? Ultimately, no one truly knows, although we have a lot of observations about how it appears to behave.
Since protons and neutrons can emit photons, I would assume they can also absorb them. Also if you managed to strip all the electrons off a large
number of atoms, you would have a cloud of highly charged nuclei that would have to be magnetically confined. Interesting, but not generally useful.
[Edited on 19-2-2004 by guaguanco]
chemoleo - 19-2-2004 at 13:17
yes, that's why I spoke of H, D, T, and He in their ionised states. They are stable...
Can protons/neutrons emit photons? under what conditions? Only during radiative decay, or without the proton/neutron actually becoming another
subatomic particle?
I am a fish - 19-2-2004 at 14:36
Atomic nucleii can have excited states. Gamma radiation by definition is the photons given of by excited nucleii decaying into a lower energy state.
Protons and neutrons are composite particles: Protons are comprised of two up quarks (charge +2/3e) and one down quark (charge -1/3e), whilst
neutrons are comprised of one up quark and two down quarks. The delta+ and delta0 bosons have the same quark combinations as protons and neutrons
respectively, but have much higher masses and a spin of 3/2 rather than 1/2. Therefore, they could be considered as being excited states of the
proton and neutron.
IgnorantlyIntelligent - 21-2-2004 at 10:47
I don't know enough about the subject to say anything useful for you I'm sorry.
I do want to say however, Isn't the univers amazing. How could all the energy and matter in it just come to be? What makes energy or anythign fo
that matter come to be. Some say "god" but it's even harder to imagin he(it) could just come to be. Sorry this doesn't help, its
just amazing is all and yes chemoleo, we really do know nothing about the universe compared to what there is still to grasp
As sad as it is, I don't think our minds can grasp what energy really is. We see it as a force, something that can do something to something else
but maybe we've got it all wrong.
[Edited on 21-2-2004 by IgnorantlyIntelligent]
what is energy?
Magpie - 21-2-2004 at 18:48
I think this is a really interesting question. When I think of energy I think of the more common types like energy due a particle's position in
a force field (gravitational, electric, magnetic, etc) and kinetic as aquired by a particle's change in velocity. But as has been stated, a
change in any of these is derived with respect to some other position or velocity. I suspect we have some who could give us some real enlightenment
on this and I hope they choose to contribute.
unionised - 22-2-2004 at 07:44
Not really my field if we are talking about high enough energy photons that you get nuclear reactions.
For low energy photons, like visible light, there would be no net absorbtion by a totally ionised plasma containing only protons.
One of the common models for the behaviour of electrons in solid matter like metals and semiconductors is the "electron gas". The outer
electrons are free to roam about in the lattice. These free eectrons do a really good job of reflecting photons and I guess that is what a bunch of
free protons would do.
The fact that you would need some sort of electromagnetic tap for them might complicate the matter. If the protons are trapped in the middle of the
field then the area just outside the middle must be a higher energy state. Perhaps the right energy photons might be absorbed and push the protons
into a higher energy orbit in the trap.