Light-induced sodium desorption from paraffin film

Sodium photoejection from a paraffin coated cell has been observed and analyzed in detail. The effect has been detected by observing the fluorescence induced by a cw dye laser. A maximum Na density of about 2.9×10^8 atoms/cm^3 was obtained by shining the cell with 1.05 W Ar+ laser green light. A progressive slowing of the dynamics of the process is reported, probably due to a change in the chemical rearrangement of the Na atoms in the coating under intense light exposure. This aging effect represents a limitation in the practical application of this kind of materials.