Saturable absorption and reverse saturable absorption play an important role in the studies of the nonlinear optical properties\nof nanoparticles at resonant excitation. With this viewpoint, nonlinear absorption processes of chemically prepared silver\nnanoparticles in deionized water were studied using femtosecond laser pulses at 400 nm. Our nonlinear absorption study\nshows that there is competition between saturable absorption and two-photon absorption in prepared Ag NPs which\ndepends on the size of the nanoparticles. We have also studied the ultrafast dynamics associated with nanoparticles which\nalso results in the direct correlation between the ultrafast timescale and the size of the nanoparticle. The excitation of Ag\nNPs at 400 nm has shown the manifestation of damped oscillation which is attributed to the radial breathing mode\noscillation due to acoustic vibration.
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