engleski

Advanced quantitative analysis of colloidal solution of metal nanoparticles produced by laser ablation in liquids

The diameter of laser synthesized colloidal nanoparticles can be derived from a volume of ablated material and absorbance at surface plasmon resonance (SPR) wavelength. The origin of such nanoparticles’ diameter has been studied in detail. The study is based on Beer-Lambert law where nanoparticle size-distribution and UV-Vis photoabsorbance data are completely exploited. Theoretically modeled diameter is verified by independent integral approach proving that simple analytical model based on equivalence of absorbance concentration and volume concentration is by most means usable for determination of diameter of laser synthesized nanoparticles in colloidal solution with sizes less than SPR wavelength. Mathematical proof that diameter obtained by simple analytical model is in fact mode diameter (most frequent diameter) of size- distribution in monodisperse limit is also presented. Furthermore, relation between mode, volume average and number average diameter of nanoparticles has been found under specific definition of number concentration of nanoparticles in colloidal solution. It is shown that mentioned diameters are not mutually independent but dependent on standard deviation of log-normal size-distribution. This is verified for size-distributions obtained independently by AFM, TEM and DLS techniques and is proposed to be universal property of log-normal size-distribution function. Since derived model is based only on two relevant experimental parameters: SPR absorbance and volume of ablated crater, it makes electron microscopy unnecessary for nanoparticles’ size determination.

laser synthesized nanoparticles ; size-distribution ; UV-Vis spectra ; mode diameter ; volume average diameter ; number average diameter ; shift factors

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