Although the work function of an element is not unique nevertheless the Kelvin Probe does have possibilities
in chemical analysis. The figure to the right shows a Scanning Kelvin Probe image of a polycrystalline aluminium sample
upon which a very thin layer (few nm thick) of gold has been applied, except in the region of the 'Al' mask. The gold
layer is invisible to the naked eye, however the aluminium-gold interface is clearly visible as the work function
difference between these two metals is approximately 1 V.