[malcolm]

malcolm asked the Naked Scientists:
   
Photons are much discussed in the context of visible light, but I never hear of the particle theory applied to any other electromagnetic 'wave' phenomena.

Have any other electromagnetic waves been tested against the photoelectric effect, radio waves for instance?

What do you think?

[Mr. Scientist]

They are all types of photon frequencies. It's the frequency which releases electrons from a metal surface.

[Mr. Scientist]

And i should say.. it specifically-requires them to have short wavelengths.

[chris]

By short wavelengths (aka high frequencies) read higher energy - shorter wavelengths pack a bigger photon punch, which is why lights of different colours liberate different amounts of charge from a photoelectric surface - explaining this was what earned Einstein his Nobel prize.

By the same token, it also explains why x-rays and gamma rays can cause cancer but microwaves can't. They are all electromagnetic waves but the highly energetic short wavelength x-rays and gamma rays have sufficient energy to ionise materials (break bonds) and hence can damage DNA. Microwaves and radiowaves, whilst eliciting a heating effect, are insufficiently energetic to break bonds and hence cannot cause cancer in the traditional sense (that's not to say they cannot produce other biochemical responses with onward malignant consequences...).

Chris

[yor_on]

I think you will like this one Malcolm, it's a cool explanation.
http://www.colorado.edu/physics/2000/quantumzone/photoelectric.html