# Basic question on photon interacting with electron

1. Aug 28, 2010

### fluidistic

If I remember well what I've read, a photon can hit an electron say in a metal (I think I refer to the photoelectric effect). We noticed that there is a particular wavelength for the photons from which they stop to be able to interact with electrons. If the wavelength of the photon is greater than this particular wavelength, then no matter how many photons hit the metal, there will be no current in the metal. While if the wavelength is equal to or lesser than the particular wavelength, then there will be a current.

I don't understand why if the wavelength is greater than the particular wavelength, no matter how many photons hit the electrons, they won't move through the metal and create a current. I don't understand why it's impossible for an electron to absorb 2 photons at a time. If the electron could absorb several photons at a time, then it would have the required energy to move through the metal and create current.
So, is it really impossible for an electron to absorb more than 1 photon at a time? Or is it very improbable? It really makes a difference to me whether there's an impossibility or an improbability. If there's a probability of $$10^{-10^6}$$, it's still possible to me.
In case of an impossibility, can you explain me why it's impossible for electrons to absorb more than 1 photon at a time? I just don't get it.

2. Aug 28, 2010

### alxm

It's just very improbable. To the extent that you probably can't measure the current caused by it.

3. Aug 28, 2010

### fluidistic

Thank you. Makes perfect sense. Questions solved.