engleski

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

A model for quantitative and calibration-free determination of laser synthesized colloidal metal nanoparticles’ diameter and concentration is developed. Model is valid under assumption that total ablated material is transferred into nanoparticles which is proved by Mie theory under dipole approximation and Beer-Lambert law using experimentally determined ablated crater volumes, size distributions and photoabsorbances. The model accounts for determination of nanoparticles’ diameter and concentration using only crater volume, photoabsorbance and position of surface plasmon resonance as experimental input. The model was developed under theoretically expected equality of nanoparticles’ concentrations obtained independently by photoabsorbances and volume of the crater (cA=cV) and under dipole approximation of Mie theory. It is shown that a priori unspecified diameter of nanoparticles in model derivation turns out to be in 1σ range of mode diameter of size distribution of nanoparticles obtained by AFM analysis. Introduction of quadrupole terms in extinction cross section gave the same result for diameter considering size ranges of used nanoparticles. Origin of obtained diameter and concentration is further examined by expanding Beer-Lambert law on nanoparticle constituents of different diameters for whole diameter distribution and consequently concentrations for entire UV-Vis spectra. It allows verification of theoretically modeled diameter by two independent approaches proving that previously derived simple model is by most means accurate and usable for determination of diameter of laser synthesized nanoparticles in colloidal solution with sizes less than SPR wavelength. In conclusion, this model allows fast and simple colloidal metal nanoparticle quantitative analysis without use of electron microscopy, mass spectrometry or relevant experimental techniques.

determination of nanoparticle concentration, Ag nanoparticles, laser synthesis of nanoparticles, colloidal nanoparticles, laser ablation in liquids

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