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What is it about free electrons that makes them so special ? For the past 100 years or so, in the field of physics it has been assumed that a free electron can neither absorb nor emit a photon because energy and momentum cannot simultaneously be conserved. This is why light cannot be conducted through a metal and since light cannot be conducted through a metal it was reasoned that this must be due to problems with the conservation of momentum, since free electrons if they emit or absorb photons would have nothing against which to recoil. Note: It turns out that this reasoning is absolutely true, it turns out that optical photons would have too great an energy resulting in too great a recoil , one which could not be accommodated without the massive nucleus to fall back against.
If free electrons cannot emit photons then how do free electron lasers work?http://journals.aps.org/prab/pdf/10.1103/PhysRevSTAB.10.034801Or what about synchrotron radiation?http://hyperphysics.phy-astr.gsu.edu/hbase/particles/synchrotron.html
Of course if you want to be completely pedantic those electrons aren't "free" because they are being accelerated. But in that case the reason that a "free" electron cannot emit a photon is that a "free" electron is not being accelerated and has nothing to do with momentum conservation. Now momentum conservation does prevent a free electron from absorbing a photon. However the free electron can and does scatter the photon:http://hutchinson.belmont.ma.us/tth/tth_example2.html
It can be shown [1] from basic electromagnetic theory
QuoteIf free electrons cannot emit photons then how do free electron lasers work?http://journals.aps.org/prab/pdf/10.1103/PhysRevSTAB.10.034801Or what about synchrotron radiation?http://hyperphysics.phy-astr.gsu.edu/hbase/particles/synchrotron.html The clue lies in the generation of x-rays. Electrons are accelerated and suddenly stopped, resulting in radiation.
QuoteOf course if you want to be completely pedantic those electrons aren't "free" because they are being accelerated. But in that case the reason that a "free" electron cannot emit a photon is that a "free" electron is not being accelerated and has nothing to do with momentum conservation. Now momentum conservation does prevent a free electron from absorbing a photon. However the free electron can and does scatter the photon:http://hutchinson.belmont.ma.us/tth/tth_example2.html Nothing at all about photons, everything is waves ? One man's meat......
Quote It can be shown [1] from basic electromagnetic theory Basic electromagnetic theory does not work with the quantum particle model.
Sorry but no. In neither of those cases are the electrons suddenly stopped. They are accelerated but not stopped. You are obviously thinking of Bremsstrahlung radiation which is related in that it has to do with electrons being accelerated but is not the same thing as synchrotron radiation (of which the radiation from free electron lasers is a subset).
Quantum mechanics is a theory of waves. The waves aren't equivalent to classical waves and have properties we normally associate with classical particles.
Except that it absolutely does. The electrostatic potential used to correctly model the atom and its electrons is exactly basic electromagnetics. It is nothing but coulombic attraction for unlike charges (proton and electron) and coulombic repulsion for like charges (electron and electron)
Quote Sorry but no. In neither of those cases are the electrons suddenly stopped. They are accelerated but not stopped. You are obviously thinking of Bremsstrahlung radiation which is related in that it has to do with electrons being accelerated but is not the same thing as synchrotron radiation (of which the radiation from free electron lasers is a subset). If you can prove that this is indeed the case and accelerating electrons can produce x-rays, you are in line for the next Nobel prize.
Quote Quantum mechanics is a theory of waves. The waves aren't equivalent to classical waves and have properties we normally associate with classical particles.I think you would have done well in the era before Max Planck, there was nothing wrong with classical theory and still isn't if you ignore certain facts, possibly you are still living in those times ?
Quote Except that it absolutely does. The electrostatic potential used to correctly model the atom and its electrons is exactly basic electromagnetics. It is nothing but coulombic attraction for unlike charges (proton and electron) and coulombic repulsion for like charges (electron and electron)Except that t doesn't ! []
No not really as it is a very well known fact. It has been used for a couple decades now to produce X-rays for scientific experiments and there are several multi-million dollar facilities dedicated to doing nothing but producing X-rays by accelerating electrons. Here are the ones supported by the US DOE: http://science.energy.gov/bes/suf/user-facilities/x-ray-light-sources/Here is a more comprehensive list for the world: http://www.lightsources.org/regions
Nope.
No it really does and you'll find zero evidence to the contrary.
QuoteNo not really as it is a very well known fact. It has been used for a couple decades now to produce X-rays for scientific experiments and there are several multi-million dollar facilities dedicated to doing nothing but producing X-rays by accelerating electrons. Here are the ones supported by the US DOE: http://science.energy.gov/bes/suf/user-facilities/x-ray-light-sources/Here is a more comprehensive list for the world: http://www.lightsources.org/regions You are pretty good at quoting sources, but you don't seem to understand the significance of what you are quoting. But if it satisfies you go ahead, believe that accelerated electrons emit x-rays. [:0]
To my query if you belong to the time before Max Planck. Quote Nope.If this is so, how come you depend so much on classical electromagnetism? If you didn't know better you would explain black body radiation in the same classical way!
Quote No it really does and you'll find zero evidence to the contrary.Nothing wrong per se but your ideas seem to be dated.
of all electron interactions, there is a very high likelihood of this being so. The point to ascertain next is how this may be possible. In order to do this it is necessary to turn to Heisenberg's uncertainty principle as related to energy and time: This equations states that if an interaction takes place in an extremely short time on the order of 10-15 sec. the Laws of Conservation of energy are not violated.
It is often said that the uncertainty principle means that energy is not strictly conserved in quantum mechanics - that you're allowed to "borrow" energy delta E, as long as you pay it back in a time delta t~ hbar/(2 delta E); the greater the violation, the briefer the period over which it can occur. Now, there are many legitimate readings of the energy-time principle, but this is not one of them. Nowhere does quantum mechanics license violation of energy conservation, and certainty no such authorization entered into Eq. 3.74. But the uncertainty principle is extraordinarily robust: It can be misused without leading to seriously incorrect results, and as a consequence physicists are in the habit of applying it rather carelessly/
This text is known as the best undergraduate text in quantum mechanics. It's used at MIT for their undergraduate quantum mechanics course.