184. Figure 4 z-Scan results for the MMAS. (a) Curves for z-scans with open (circle) T(I) and closed (square) T pv(I) apertures at radiation wavelengths of 442 nm (red points, 60 W/cm2) and 561 nm (blue points, 133 W/cm2) for the MMAS sample (L = 2.7 mm). (b) IWP-2 nmr Profilometer images for the beam waists ω 0. Figure 5 z-Scan results for the composite. Curves for z-scans with open (circle) T(I) and closed (square) T pv(I) apertures at radiation wavelengths of 442 nm (a) (red points, 19 W/cm2; blue points, 54 W/cm2) and 561 nm (b) (red points, 40 W/cm2; blue points, 93 W/cm2)

for the composite sample (L = 2.7 mm) containing Fe3O4 nanoparticle with a 0.005% volume concentration. The experimental curves T(I) and T pv(I), which contain Go6983 mw information about ΔT and ΔT pv, showed that only the reverse saturable absorption of yellow radiation occurred in pure MMAS (Figure 4a). In contrast, the composite manifested the expected optical

response: the shape of the experimental curves T(I) and T pv(I) indicated the saturable absorption of visible radiation in the composite and a negative change in its refractive selleck kinase inhibitor index (Figure 5), and the values of ΔT(I) and ΔT pv(I) increased linearly with increasing intensities of blue (Figure 5a) and yellow (Figure 5b) radiation. The approximation of T pv based on the theoretical curves (solid lines in Figure 5) was performed using the equation [42]: (2) where the coupling Adenosine triphosphate factor ρ = Δα × λ / 4π × Δn and the phase shift due to nonlinear refraction ΔΦ = 2π × Δn × L eff / λ had the following values: ρ = 0.09 and ΔΦ = −0.23 and −0.5 for blue radiation with intensities of 0.019 and 0.054 kW/cm2 and ρ = 0.05 and ΔΦ = −0.7 and −1.45 for yellow radiation with intensities of 0.04 and 0.093 kW/cm2. Discussion The saturable

absorption of visible radiation with intensities less than 0.14 kW/cm2 in the composite and the negative change in the refractive index were due to the presence of Fe3O4 nanoparticles since pure MMAS showed only the relatively weak reverse saturable absorption of yellow radiation. Therefore, the experimental data ΔT(I) and ΔT pv(I) obtained for the composite could be used to calculate the values of Δα(I) and Δn(I) for Fe3O4 nanoparticle arrays (Equation 1), and these values are listed in Figure 6. Figure 6 The values of changes in the absorption coefficient, refractive index, and polarizability of Fe 3 O 4 nanoparticles.