I was always under impression that electron affinity is defined (and listed in tables), as energy change when isolated atom in gaseous phase gains an electron. However, I was lately told that the same term is used for solids in "standard semiconductors references", like in Sze's Physics of semiconductor devices. Obviously that would mean quite different thing and can be confusing at first. Unfortunately I don't have access to any books to check if that's the case. Anyone can confirm?