Octahydroacridine thin films grown by matrix-assisted pulsed laser evaporation for non linear optical applications

We report on the thin film growth of 1,2,3,4,5,6,7,8-octahydroacridine (OHA) by matrix-assisted pulsed laser evaporation (MAPLE), starting from a frozen solution of 1% OHA dissolved in methanol and using a Nd:YAG laser emitting at 266 nm wavelength with fluences in the range 0.1-1 J/cm2. The optical properties were studied by spectroscopic-ellipsometry (SE), while Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), and scanning electron microscopy (SEM) were performed for structure and surface morphology investigation. Second harmonic generation (SHG) capabilities of the thin films were investigated by using a tunable Ti:sapphire laser with maximum emission centred in near infra-red. The peak of emitted photons is located at 388 nm, therefore half the wavelength of the initial photons (776 nm). The semi logarithmic dependence of SHG intensity on incident power is almost linear, except the value obtained at highest power of incident photons. This value indicates a local changing of sample due to the heating produced by the high-power incident beam.