Classical Explanation for Photoelectric Effect

[granpa]

even if it is absorbing energy from a square region equal in width to the wavelength of visible light (the maximum that it could classically absorb from) there should still be a noticeable delay. yet there isnt.

Zapper says that they have now succeeded in detecting a delay. I'll take has word for it.

 

[ZapperZ]

even if it is absorbing energy from a square region equal in width to the wavelength of visible light (the maximum that it could classically absorb from) there should still be a noticeable delay. yet there isnt.

Zapper says that they have now succeeded in detecting a delay. I'll take has word for it.

Note that I said "response time". I'm trying to use the proper terminology for it because it has a specific meaning, and I would hope that people can google it and find exactly what it means as far as photocathodes are concerned.

And since I've also mentioned elsewhere of the Spicer's 3-step model of photoemission, I would hope people would go look for that as well and figure out why there is such a thing as a "response time" in photoemission. It isn't as trivial as calling it "delay" time.

Zz.

 

[granpa]

I thought others might find this useful:

http://www.eurekalert.org/pub_releases/2009-05/ksu-kfl052109.php

"With the help of ultrashort laser pulses, the motion of electrons can now be followed in time. "

In agreement with a recent experiment, their calculation shows that electrons of a metal surface that are near atomic nuclei are photo-emitted with a delay of about 110 attoseconds relative to another type of electron. These conduction electrons are not attached to individual atoms and enable metals to conduct electricity.

While Einstein's model is not wrong, it is not a proof for the particle-character of light, Thumm said. Einstein published his model about two decades before modern quantum theory was developed. Modern quantum theory of matter predicts the emission of an electron even when light is regarded as a classical electro-magnetic wave.

heres another nice article on the basics of the photoemission process:
http://prola.aps.org/abstract/PRA/v9/i2/p976_1

this article seem to mention something about a time delay:
http://bjps.oxfordjournals.org/cgi/content/citation/III/10/109

http://adsabs.harvard.edu/abs/1968PhLA...27..343C

 

[Vanadium 50]

I think what granpa is saying is ...

Well, if he were to post a reference to what he is claiming, we could all read it for ourselves rather than guessing.

I think it's also important that we distinguish between a delay of nano-seconds and a pre-emission of minutes.

 

[ZapperZ]

http://www.eurekalert.org/pub_releases/2009-05/ksu-kfl052109.php

You have done this several times, providing a link that is tangential to the topic being discussed. So STOP IT. It is confusing the issue, and has caused this thread to go into a million different directions.

I do not see the point in this link, since you have made no attempt at extracting what is relevant in this PRESS RELEASE to the issue being discussed in this thread.

Zz.

 

[Count Iblis]

The "classical explanation" is actually more quantum mechanical, in the sense that the light described by Maxwell's equations is in a coherent state (in the general quantum mechanical meaning of "coherent", i.e. the photons are not entangled with the rest of the universe), while what we call the "quantum explanation", is more classical (single particle collisions which is incoherent).

 

[granpa]

heres your dang'd reference:
http://www.physnet.org/modules/pdf_modules/m213.pdf

or rather 'a' reference. its not the same article that I read before.

(and it says 'hours' not 'minutes')

here is another one:
http://www.phys.unsw.edu.au/PHYS2040/pdf/PHYS2040%2009%20Quantum%20Physics%20Lecture%202%20-%20Handouts.pdf

here is the google search that finally worked:
http://www.google.com/search?q=phot...ent=firefox-a&start=10&sa=N&cts=1243444033248

 

[granpa]

this pdf offers an absurdly simply solution to the time lag question. it suggests that every atom (or material as a whole) is 'preloaded' with (a reservoir of) energy because its been slowly absorbing background radiation over a long period of time. surely it can't be that simple. there must be some way of testing this.
http://www.wbabin.net/science/maji4.pdf

Actually the electrons in the metal surface are continuously absorbing
energy from external electromagnetic waves which are always present even if no external
light source is applied as complete darkness is unattainable. Therefore the loosely bound
electrons get energized continuously until they got enough energy to escape from the
metal surface. As this is impossible to know when an electron starts absorbing energy i.e.
there is no way to detect the theoretical time lag.

editr maybe the material is simply 'born' with this 'energy reservoir' (which the materials electrons share). in the past I would not have believed that a collection of atoms could have such a behavior but knowing now what I do about the seemingly impossible quantum mechanical properties of solids (like superconductivity) I'm prepared to think that there might actually be something to this.

most of the papers on the site mentioned above appear to be garbage. but the front page contains a very nice list of 'historical' papers down at the bottom.

 

[malawi_glenn]

this pdf offers an absurdly simply solution to the time lag question. it suggests that every atom is 'preloaded' with energy because its been slowly absorbing background radiation over a long period of time. surely it can't be that simple. there must be some way of testing this.
http://www.wbabin.net/science/maji4.pdf

but seriously, we discuss peer reviewed articles here, not some Indian mumbo jumbo crap

 

[ZapperZ]

this pdf offers an absurdly simply solution to the time lag question. it suggests that every atom is 'preloaded' with energy because its been slowly absorbing background radiation over a long period of time. surely it can't be that simple. there must be some way of testing this.
http://www.wbabin.net/science/maji4.pdf

That already caused me to suspect that whoever wrote this has no clue of the difference between atomic physics and solid state physics, that the standard photoelectric effect on METALS reflects MORE on the solid nature of the material than the individual atoms that make up the metal. For example, try to find an atom that can produce a dispersion curve similar to my AVATAR. You'll find NONE!

So why are you propagating such nonsense here? Are you bored and would like valid and reputable sources on photoemission phenomenon?

Zz.

 

[granpa]

it wasnt the pdf that I wanted to discuss. it was the idea.

'atom' was my choice of words and it was a poor choice. it does not appear in the pdf. I was trying to give a short quick explanation, from memory, of what the author was saying but I got mixed up. the author never said 'atom'.

my thinking is that it is the material itself as a whole (not individual atoms) that has some kind of 'energy reservoir'. and perhaps every material is 'born' with this 'energy reservoir'. then the effect wouldn't depend on the samples history. (btw, liquids also produce the photoelectric effect)

as each electron continuously absorbs energy from light waves it sends this energy (continuously) to this reservoir but at each moment there is a small probability, which depends on the frequency/frequencies, that it will be ejected (the energy coming from the reservoir)

like I said below:

in the past I would not have believed that a collection of atoms could have such a behavior but knowing now what I do about the seemingly impossible quantum mechanical properties of solids (like superconductivity) I'm prepared to think that there might actually be something to this.

low energy photons wouldn't produce the photoelectric effect because the electrons couldn't escape the material due to its 'work function'. (which is the standard explanation anyway)

 

[Vanadium 50]

So why are you propagating such nonsense here?

Good question - but do you really want an answer?

The idea that atoms somehow slowly "preload" themselves with energy, it violates a number of experimental observations:

• All atoms of a given isotope are identical
• The photoelectric effect doesn't depend on previous applications of the photoelectric effect to the same sample (barring photocathode damage, of course)
• High intensity low energy photons do not induce photoemission

Maybe more.

 

[ZapperZ]

it wasnt the pdf that I wanted to discuss. it was the idea.

'atom' was my choice of words and it was a poor choice. it does not appear in the pdf.

Then obviously your "idea" was clearly wrong.

Zz.