A new method for measuring refractive index and thickness of liquid and deposited solid thin films

Segmental Dynamics of Ethylene Oxide-Containing Polymers with Diverse Backbone Chemistries

“…The standard assumption is that the square of the refractive index, n , corresponds to ε ∞ and should equal the observed high-frequency plateau in the permittivity ε′ at temperatures below T g . Prism coupling is an optical method (λ = 633 nm) of measuring the refractive index where no orientational relaxations occur at such a high frequency so that n 2 is strictly the electronic contribution to the dielectric constant. − The small discrepancy between the two methods of determining ε ∞ arises from a weak relaxation of strength Δε ∼ 1 that occurs at lower temperatures or higher frequencies than observable in the frequency and temperature range probed in our experiments. This relaxation is the so-called γ process observed in the literature at −130 °C that corresponds to local twisting motion of PEO segments in the glassy state .…”

“… a Optical ε ∞ values are obtained by 633 nm wavelength prism coupling b DRS ε ∞ values are obtained below T g and at 10 6 Hz. …”

“…Samples were dried under vacuum and stored under Ar before being applied as ∼1 mm films directly to the prism under ambient conditions. Refractive indices were determined by the sharp drop in signal at the critical angle knee and are accurate to ±0.001. − …”

Depth profiling with standing waves. Recovery of thin-film functional group distributions

“…After spectroscopic examination of the composite structures the top layers were removed sequentially by rinsing with the appropriate solvent. The interface positions were then determined both by interferometry and by measuring the resonant coupling angles (32)(33)(34)(35)(36)(37)(38). Radiation from an Ar+ laser was coupled into the composite structures with an LaSF-9 prism (n = 1.8624 at 514.5 nm).…”

Light induced refractive index changes in PMMA films doped with styrene

“…The refractive index of the polymer film n is lower than n. Thus the film must be treated as leaky waveguide [4,5]. When the/aser beam enters the prism ( fig.…”