absorption spectra

[derek w]

Question.When an atom absorbs a photon and the electron jumps to a higher energy level e.g. from n to n1 or n1 to n2.

The frequency of the photon being a mid point between n and n1 or n1 and n2.

The wavelength of the electron must fit the circumference.

My question is does the wavelength of the electron change as it jumps between levels?

I assume that it must do,so that a different frequency of photon is required at different levels,but I am not sure?

[swansont]

The energy of the photon (and thus the frequency and wavelength) is equal to the energy difference between the two states.

 

What happens during the absorption is something that, AFAIK, has not been investigated, and it's possible that it can't be.

[derek w]

Do electrons knocked out of different elements have different wavelengths.

[swansont]

Do electrons knocked out of different elements have different wavelengths.

Are you asking if the electrons have different wavelengths or if the light has different wavelengths?

 

The light has a maximum wavelength, because it has to have the ionization energy as a minimum. But any wavelength shorter than this will knock an electron out, and the electron's energy (and thus its energy, momentum and wavelength) can have any value.

[derek w]

So if a hydrogen atom,consisting of a (proton and a captured electron),absorbs a photon,and the electron is knocked out,the electron and proton take away the energy of the photon,the photon no longer exists.visa versa if an ionized hydrogen atom captures an electron,any excess energy is taken away,by creating and emitting a photon.

 

Basically photons do not exist inside atoms.

[swansont]

So if a hydrogen atom,consisting of a (proton and a captured electron),absorbs a photon,and the electron is knocked out,the electron and proton take away the energy of the photon,the photon no longer exists.visa versa if an ionized hydrogen atom captures an electron,any excess energy is taken away,by creating and emitting a photon.

 

Basically photons do not exist inside atoms.

Correct.

 

Photon number is not a conserved quantity.

[derek w]

OK,thanks.

If it were anti-hydrogen atom,consisting of anti-proton and positron,emitted photons would be identical,anti-hydrogen and hydrogen having the same emission spectra.

A photon emitted from anti-hydrogen could be absorbed by hydrogen.

[John Cuthber]

Yes, a photon is it's own anti-particle.

[alpha2cen]

How does the photon come from the empty space?

[illuusio]

How does the photon come from the empty space?

 

 

It doesn't. It's created from the "stuff" between electron and nucleus, that's my hypothesis. Modern physics don't have answers to your question because physics is nothing but math these days.

[O'Nero Samuel]

Yes, a photon is it's own anti-particle.

Now this is confusing. How can a photon be its own antiparticle? Taken literally does that imply that a photon can extinguish another photon? If so when and why does this happen? And what happens with the initial energy that created the photons in the first place?

[alpha2cen]

It doesn't. It's created from the "stuff" between electron and nucleus, that's my hypothesis. Modern physics don't have answers to your question because physics is nothing but math these days.

 

Similar concept.

This is a gravity case. But it does not happen.

[illuusio]

Similar concept.

This is a gravity case. But it does not happen.

 

 

But in that gravitation case object absorbs energy and radiates it too. Photon experiences blue shifting.

[derek w]

How does a photon come from empty space?

 

If you have a 4th dimension then you can mathematically,oscillate a single point in 3d space in the 4th dimension.

 

If S=single point in 3d space then you can have (S) oscillating between ( -sec/10^18) to (+sec/10^18).

 

But that's just maths.

Edited October 26, 2012 by derek w

[illuusio]

How does a photon come from empty space?

 

 

Maybe somebody sent it?

[swansont]

Now this is confusing. How can a photon be its own antiparticle? Taken literally does that imply that a photon can extinguish another photon? If so when and why does this happen? And what happens with the initial energy that created the photons in the first place?

If that were to happen, you'd create a photon and antiphoton. IOW, the situation would look no different. But photons generally just pass through each other.

[Phi for All]

It doesn't. It's created from the "stuff" between electron and nucleus, that's my hypothesis. Modern physics don't have answers to your question because physics is nothing but math these days.

!

Moderator Note

You know better than to hijack a mainstream science thread with your personal, unsupported pet theories. I'm going to recommend that you be suspended again, this time for two weeks, to give you time to work on re-reading the rules.

[Enthalpy]

Referring more to the beginning of this thread...

 

The quantity is conserved in a atom's electron absorbing a photon is energy, not wavelength. Both are linked in a way for photon, but the relation differs for electrons.

 

Electrons in an atom are trapped, so they don't propagate, and don't have a usual wavelength. One does define a wavenumber or vector but it's a mathematical imaginary number, telling that the probability of observing the electron far from the nucleus vanishes quickly - trapped. The equivalent of the wavelength then is simply the radius of the orbital - I like to say "the radius of the electron" instead of "its orbital". You can call it properly a fading wave, though this term is more common with photons than electrons, and photons are then called "virtual". It boils down to cos(x) versus exp(-x).

 

By telling "the electron is a wave", QM explains this radius, which is the reason why matter has a volume.

 

What happens "when a photon is absorbed" isn't clear tome, but what happens when the atom is illuminated was observed at a Munich university. The probability of observing the electron in the excited states raises over time just as theory predicts, with a sin²(t) that is faster when the field is stronger. After some time, the probability of the excited state decreases again according to sin²(t), and this is called "stimulated emission". If you manage to have >50% atoms in the excited state, which isn't very natural and need "pumping", then the incoming light de-excites more atoms than it excites, and you can harvest a net energy ; this is called the Laser effect.

 

QM describes this with more details. Stationary states are the ones that don't evolve over time, where nothing happens, but are not the only ones. If these states have energies separated enough then temperature doesn't suffice to put the particles in excited states. Provided efficient mechanisms exist for de-excitation (it can take very long for hydrogen atoms emitting the 21cm radio wave, or months for some excited nuclei) then particles group to the lowest available stationary state - knowing that at most two fermions like electrons can share one state. This is the usual state of atoms and molecules.

 

Now if the atoms is illuminated at the proper frequency, some electron(s) can have a state which isn't stationary any more - it evolves. Though, mathematics tell that the wave (the electron) is a weighted sum of stationary states as long as the particle remains trapped. As illumination continues, the electron's evolving state consists of more of the excited state and less of the lower state.

 

This compound state:

- Has a probability distribution that moves over time at the frequency of the energy difference. As opposed, it doesn't in a stationary state.

- Has an electric polarization that moves at said frequency. That's why the compound state radiates an electromagnetic wave while a stationary state doesn't.

- Reciprocally, the illumination at the frequency of the energy difference acts on the compound state thanks to the polarization. It changes the composition of the compound state over time, following sin²(t) and 1-sin²(t).

 

Some pairs of stationary states combine to produce an evolving state able of radiating efficiently and EM field, for instance s and p orbitals. This is when the quantum numbers fit one photon. Then the electron de-excites quickly. Other pairs, for instance s and s states, result in sum with no polarization, and then the "transition is forbidden" and the excited state can last longer, like minutes for singlet oxygen, and more for the 21cm ray.

 

Same for photon absorption, where only the energies corresponding to allowed transitions are absorbed.

 

Usual light intensity takes many periods to excite an electron, hence light frequency must match the transition so its effect cumulates over time - the resonance is sharp. But strong laser light, concentrated over area and time, can for instance ionize air's nitrogen despite its frequency is completely mismatch. People speak of "multi-photon absorption"; I understand it (wrongly?) as needing no resonance to accumulate the effect over time, thanks to the available power. I've seen no description of it (nor of crystals that double or triple light's frequency...) in terms of QM. Similarly for light emission: the shorter light pulses (at the same university) are about half a period short, and use electrons that have less than the energy of an excited state...

 

Also fun: though stationary states have an non-mobile probability envelope (psi squared) the electron does have a phase everywhere because the wave psi is a complex number. This allows the phase to rotate by an integer number along a geometric turn around the nucleus, and this number is the orbital momentum. In that sense, the electron is immobile and doesn't radiate, but its phase rotates over time and explains the orbital magnetic moment.

 

=====================================

 

Photons disappearing:

 

Particles can appear and disappear. Electrons do it in beta radioactivity for instance. Thousands of particles are created during a collision in a particle accelerator - including fermions, and not just small ones.

 

What is conserved are not individual particles but for instance the total electric charge, the total moment, the total energy+mass, and more numbers.

 

This is not just a rearrangement of sub-particles, as for instance the electron is an elementary particle for any experiment doable to date, and does not pre-exist in a neutron that transforms into proton, electron and neutrino in beta radioactivity.

 

A lonely photon won't disappear since this wouldn't conserve energy, momentum and some more. But it disappears if absorbed by an electron, just as an electron (or some other particles) can create it.

 

=======================

 

Anti-hydrogen: the most common theories tell its transitions are the same as for hydrogen. Though, the subject is being investigated as it would give clues to chose between new theories.

 

Whether the neutrino is its anti-particle is still an open question, but the photon is not a debate - as far as I know, and I ignore much.

 

======================

 

"Photon comes from the empty space" results from a wrong representation of orbitals as circles.

The electron is there. Both orbitals occupy this portion of space.

 

Graviton and energy transition... Gravitation waves have not been observed, we have no consistent theory about gravitation quanta... This kind of diagram is highly speculative. Can it result from a single mass, or only a pair at least? And whether it happens: please first make the experiment to determine that, and kindly tell us afterward.

[John Cuthber]

Now this is confusing. How can a photon be its own antiparticle? Taken literally does that imply that a photon can extinguish another photon? If so when and why does this happen? And what happens with the initial energy that created the photons in the first place?

The annihilation creates a pair of photons.

[O'Nero Samuel]

The annihilation creates a pair of photons.

Creates a pair of protons? IT WAS THE PAIR THAT INTERACTED IN THE FIRST PLACE! I think the proton-antiproton perspective sinks easier. Would I be wrong to think that on interaction, one proton creates a back spin off the other? This to me seems to be the only logical way protons can pass through each other and still be differentiated relative to each other.

 

The annihilation creates a pair of photons.

Creates a pair of protons? IT WAS THE PAIR THAT INTERACTED IN THE FIRST PLACE! I think the proton-antiproton perspective sinks easier. Would I be wrong to think that on interaction, one proton creates a back spin off the other? This to me seems to be the only logical way protons can pass through each other and still be differentiated relative to each other.

[Enthalpy]

[...]

I can't make a sense from the scientific-looking vocabulary dumped here, sorry.

An anti-proton is easily distinguished from a proton because it's a different particle.

"Pass through each other" looks like an attempt to use at particle scale the representations of macroscopic scale.

Edited October 30, 2012 by Enthalpy

[derek w]

The discussion has gone from photons to protons?

[swansont]

Creates a pair of protons? IT WAS THE PAIR THAT INTERACTED IN THE FIRST PLACE!

Photons? This is perfectly consistent with nothing at all happening, because a photon and an antiphoton are the same thing.