Photoelectric effect / Discussion

This is the discussion related to the wiki page Photoelectric effect.

Jialan Zhang 17 Mar 2009 01:04

Hi, zengmin, good job! It is excellent to see your paper connect the application and the theory here.

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Zengmin Xia 18 Mar 2009 00:32

Actually, Photoelectron Spectrum connected with intensive knowledge about quantum theory, such as EDJDOS and DOS can be used to interpret the three-step model.

Kuoting 17 Mar 2009 22:18

Nice job Zengmin!It clearly introudces the concept of Photoelectric effect, and I would like to cite your page in my topic to explain one fundamental formulas.

yuan xue 18 Mar 2009 00:59

zengmin, photoeffect can be obtained from a material which is irradiated by UV, however, it may not be the main effect when the same intensity of x-ray is applied to irradiate the same material because of its high energy that probably leads to the Compton effect. Did this happen in your experiment? Thank you.

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Zengmin Xia 18 Mar 2009 01:25

There may be some misunderstanding. In my experiment, I use UV irradiation as surface treatment for my substrate of biomimetic coating instead of research about photoeffect.
Yours is a good question about which will happy under X-ray . It depends on the energy of photon. If the photon is of lower energy, but still has sufficient energy (in general a few eV, right around the energy of visible light), it can eject an electron from its host atom entirely (a process known as the photoelectric effect), instead of undergoing Compton scattering. In addition, Higher energy photons (~MeV) may be able to bombard the nucleus and cause an electron and a positron to be formed, a process called pair production.Compton scattering belong to Mid-energy phenomena.
http://en.wikipedia.org/wiki/Compton_scattering

A-Rivera 18 Mar 2009 02:16

Hi Zegmin,

Maybe you can include this link on your page. In this link the photoelectric effect is illustrated for light of different wavelengths and intensities.

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Zengmin Xia 19 Mar 2009 02:15

Thanks for your suggestion, I will add it.

Liang 18 Mar 2009 03:04

Dear Zengmin, good job. I don't quite understand your figure in section 3. What dose the shadow area across the forbidden band mean? Would you please say something about that? Thanks!

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Zengmin Xia 19 Mar 2009 02:14

here is the information about secondaries. "In the transport step the photoelectron distribution created at any given depth in the sample travels towards the surface of the sample and may undergo elastic (see previous) or inelastic scattering processes with the atomic systems present in the sample. Besides inelastic interactions in which the photoelectrons loose a discrete amount of energy (such as the interaction with plasmons) a signicant part of them will undergo random inelastic collisions loosing partially (or totally) their kinetic energy. These are known as secondary electrons (secondaries) and do not carry information on the initial kinetic energy they acquired. The secondaries cause a raising back-ground on the low kinetic energy side of each primary peak and determine the spectrum to have afinite intensity up to zero kinetic energies."