Effect of x-ray irradiation on Co-phthalocyanine thin films studied by surface plasmon resonance

Abstract

We explore here the effect of x-ray irradiation (7.7 keV) on Co-phthalocyanine (CoPc) thin films using surface plasmon resonance (SPR). We have found a small and partially reversible modification of the SPR spectra of CoPc in CoPc/Au bilayers upon irradiation. For a beam intensity of ~1011 photons · s−1 · mm−2 and an irradiation time of the order of 1 h, we estimate small variations of the order of ~1–5% in the refractive index associated with the scattering of the x-rays with the soft matter. A Raman study of the irradiated regions did not show structural modifications, suggesting that the observed variations in the optical properties of the CoPc films are related to modifications of their electronic configuration.