Subject: Photoelectric effect - free electrons or those of atoms?

In the photoelectric effect, are you striking free electrons in the metal 
lattice or ones within their atomic shells with phtons? Also, what does an 
electron do with the energy it recieves from electrons bellow the threshhold 
frequency/ energy? Does it just gain that (small) amount of kinetic energy? 
Because if this was the case, then surely you could hit the same electron in 
rapid succession with lots of low energy phtons till it gains sufficient energy 
to escape?
Thanks. :-)

NB - I have asked this question before and you told me to look in the archives. 
I have done so but was unable to find a sufficient answer.

Re: Photoelectric effect - free electrons or those of atoms?