Particle Size Distribution And Concentration Measurement Of Rotationally Symmetric Gold Nanoparticles Based On Extinction Spectrum Spectroscopy

Different from the bulk materials,gold nanoparticles have localized surface plasmon resonance phenomenon,which results in gold nanoparticles exhibiting strong light absorption and scattering properties.Their unique optical properties are widely used in biology and medicine,Energy,environment and materials.The size and concentration are important parameters of the gold nanoparticle system and determine the nature and behavior of the gold nanoparticles in practical applications.The wide resonance peak position tunability of non-spherical gold nanoparticles makes them more valuable in applications.The accurate measurement of the size distribution and concentration of non-spherical gold nanoparticles is of great importance for the size control of non-spherical gold nanoparticles in preparation and performance control in applications.important meaning.The use of extinction spectroscopy to measure the size distribution and concentration of spherical gold nanoparticles has the advantages of high accuracy,simple equipment and no contact.The rotationally symmetric gold nanoparticles have two-dimensional size distribution and concentration inversion problems.The spectral extinction method of spherical gold nanoparticles cannot invert the two-dimensional size distribution at the same time.In view of this limitation,this paper improves the method and verifies the reliability of the improved inversion algorithm.In this paper,based on the extinction method of measuring the particle size and concentration distribution of spherical gold nanoparticles,using the relationship between the extinction spectrum of the rotationally symmetric gold nanoparticles and the two-dimensional size concentration,combined with the T matrix program to calculate the three different sizes of the rotationally symmetric gold nanoparticles Parameters and wavelength extinction cross section,thus establishing a linear equation system containing two-dimensional size concentration distribution information.Using the non-negative Tikhonov regularization method to solve the equations,the two-dimensional size concentration distribution of rotationally symmetric gold nanoparticles is obtained.In order to effectively improve the operating speed of the inversion program,the database of extinction cross-sections is established.The wavelength range of the three databases is 300-1100 nm,the interval is 2 nm,the size range is 20-130 nm,the interval is 2 nm,and each database has a total of about 125 Ten thousand extinction cross-section data,and analyze the extinction characteristics ofthe three particles in the database.Theoretical simulation results show that the relative errors of the average value of the two-dimensional size of the gold nano-ellipsoid and the gold nano-cylinder are less than 15%,the relative error of the average aspect ratio of the gold nanorod is less than 5%,and the relative error of the average length is less than 10%,the relative error of the particle number concentration of the three particles does not exceed 15%,which verifies that the algorithm is stable and has high accuracy.Using the laboratory extinction spectroscopy experiment system,based on the extinction spectrum of the gold nanorod particle sample solution,inverse measurement of the gold nanorod diameter distribution and concentration,the measurement results were compared with the electron microscope scanning results and the nominal value,and the results showed the average aspect ratio The error between the inversion result and the SEM measurement result does not exceed 30%,the length average inversion result does not exceed 15%,and the concentration inversion result is close to the nominal value.The experimental results show that the size and concentration results of gold nanorods measured by extinction spectroscopy can better reflect the size distribution and particle number concentration in the particle system,and provide an effective and quick measurement method for the simultaneous measurement of the size distribution and concentration of polydisperse rotationally symmetric gold nanoparticles.