Vapor deposition of polystyrene thin films by intense laser vibrational excitation

Polystyrene films were deposited using resonant infrared pulsed laser depositions (RIR–PLD). Thin films were grown on Si(1 1 1) wafers and NaCl substrates and analyzed by Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). The depositions were carried out in vacuum (10−4–10−5 Torr) at wavelengths 3.28, 3.30, 3.42 and 3.48 μm which are resonant with CH2 stretching modes in the polymer. We also attempted to deposit a films using non-resonant infrared (RIR) excitation (2.90 μm). At this wavelength no films were deposited, and evidence for laser-induced damage to the target can be seen. RIR–PLD is a fundamentally new approach to polymer thin film growth as the absorption of radiation resonant with vibrational modes allow the energy to be deposited into the polymer and transfers between macromolecules in such a way as to promote efficient, non-destructive desorption into the gas phase.