Photoelectric effect in nonpolar liquids

The photoelectric effect on a metal electrode can be utilized to measure the energy of the electronic conduction level in a nonpolar liquid. In vacuo, at 0 K, the work function of the metal, given by the limiting frequency of the light, Vq above which electrons are emitted  

Since the electron transfer into the liquid is an adiabatic process, injection occurs into the delocalized state. In solid-state physics this energy pertains to the bottom of the conduction band. At temperatures T 0 K, emission of electrons is already observed at light frequencies below Vq. It is a consequence of the thermal motion of the metal electrons. Electronic states above the Fermi level become occupied. The theory of photoelectric emission developed by Fowler (1931) takes this effect into account. Ihe normalized photoelectron current igi/Iph is written as 

Although the Fowler theory applies to electron emission in vacuo, it can also be applied to the emission in nonpolar liquids. The liquid is considered to represent a constant, frequency-independent attenuation of the emission process. 

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