Arrival time measurements of films formed by pulsed laser evaporation of polycarbonate and selenium

By measuring the rapid change in reflectivity of a substrate during film growth induced by pulsed laser evaporation, the time‐of‐arrival profiles of material emanating from polycarbonate and selenium targets were determined. Results for both targets are reasonably well described by Maxwell–Boltzmann velocity distributions. Selenium evaporation appears to be atomic while for polycarbonate a range of masses are involved. The high velocity of the material leaving polycarbonate strongly suggests that small polymers are not transported directly. The mechanism for polymer film formation must involve repolymerization on the substrate of species not weighing more than a few hundred amu. For both polycarbonate and selenium the time‐of‐arrival profiles were affected very little by changing the excitation wavelength from 248 to 1064 nm.

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