Research On The Photo-thermal Effect And Photo-acoustic Effect Of Gold Nanoparticles

With the rapid development of nano-materials at the end of the twentieth century and the beginning of the twenty-first century,AuNPs are gradually showing a broad application prospects in the fields such as the biography imaging and the cancer therapy due to its excellent photo-thermal effect and photo-acoustic effect.Obviously,the research on the AuNPs can be of great practical significance to the health of modern people and the development of society.In this paper,we first discussed the light absorption process of AuNPs caused by the local surface plasmon resonance absorption by means of light scattering theory of metal particles.The results showed that for the wavelength about 530 nm of incident light the spherical Au NPs will have a strong absorption,and the redshift of the absorption peak will occurred with the particle size increase.Secondly,the photo-thermal properties of the AuNPs colloid were analyzed by a very simple macroscopic phenomenological model for measuring the temperature curves of the gold nanoparticles colloid under the continuous laser irradiation at the wavelength of 532 nm.The analysis showed that by establishing a simple heat dissipation model,the measured temperature curve can be fitted,and a high incident light power and a proper heat treatment will result in better fitting.The value of the photo-thermal conversion efficiency of the AuNPs colloid is about 0.7,and the value will fluctuate with different variables such as different irradiation power.Finally,by means of Rayleigh-Plesset equation,a series of studies on the cavitation phenomena excited by the AuNPs in the photo-thermal heat process were carried out.The research showed that higher incident pulsed light energy will result in a larger size cavitation bubble and more intense photo-acoustic signal.Furthermore the signal amplitude and the incident light energy will be a linear relationship.In the experiment part,the article mainly focused on the comparison between the simulation results and the photo-acoustic signal induced by the AuNPs colloid.The pulse width and wavelength of the incident laser in the experiment were 5ns and the 532 nm respectively.