Changing the optical properties of poly(methyl methacrylate) superficial films during UV irradiation

Infrared spectra of the main optical properties of poly(methyl methacrylate) thin films

“…The measured size is the transmittance. The transflection spectra thus obtained are similar to the transmission spectra [4,5].…”

“…The penetration depth is greater than the thickness of the superficial film (5.3 μm) in almost all spectral regions. Radiation refracted at the air-film interface can reach the polymer-metal interface and is reflected on the metallic mirror (with a high reflectance coefficient R23=0.894) [4].…”

“…The extinction coefficient k, the absorption coefficient α, the real part of the conductivity σ1, the imaginary part of the complex electric modulus M2, the surface energy loss function SELF and the dielectric loss tangent tan δ have IR spectra with an appearance similar to that of the imaginary part of the permittivity ε2. For this reason, Jitian and Bratu [4] only presented the change in the IR spectrum aspect of the extinction coefficient k during UV irradiation of the PMMA film. The refractive index n and the real part of the complex electric modulus M1 have IR spectra with an appearance similar to that of the real part of the permittivity ε1.…”

“…The modeling process consists of introducing into the expression of permittivity described by the Drude-Lorentz equation the dispersion parameters ε∞, ν0, νp , γ corresponding to the independent oscillators of the different groups in the polymer structure and adjusting them until the transmittance Tmodel obtained from the modeled permittivity approximates the best Texperimental transmittance corresponding to the reflection-absorption spectrum of the polymer [4,5,7].…”