Laser Carbon Plasma Characteristics And Its Preparation Of Graphene

In recent years,carbon nanomaterials have attracted wide attention from scientists due to their unique physical and chemical properties,and they have important applications in new energy,information,and biomedicine.Laser-induced carbon plasma has also received great attention in the past few years due to its application in the preparation of carbon nanomaterials.Plasma characteristics are closely related to laser energy,ambient gas pressure,and material properties.In order to better optimize the experimental parameters of carbon nanomaterials,we need to further study the characteristics of laser-induced carbon plasma.In this dissertation,the internal characteristics of plasma particles are studied from the aspects of plasma plume and emission spectroscopy.Then the effects of different conditions on pulsed laser induced graphene were studied.The main contents are as follows:?1?The direct imaging method was used to study the characteristics of pulsed laser-induced carbon plasma plume and particles?C₂,C⁺?was study through direct imaging method at various air pressures,and the angular distribution of the plume expansion at various air pressures was study by use of the polar distribution diagram.Since C₂ plays an important role in the formation of carbon nanoparticles,the effects of different air pressures on C₂ formation were investigated.The emission position of C₂ and C⁺is discerned by the narrow bandpass filter,and the formation process of C₂under different air pressure conditions is analyzed.By observing the positions of the C₂and C⁺emission peaks,the role of C⁺in the formation of C₂ was explored.?2?Pulsed laser induced carbon plasma was diagnosed by emission spectroscopy.The early emission spectrum is continuous spectrum,and the electron temperature of the carbon plasma is estimated by using the black body radiation formula.When the line spectrum appears,the electron temperature is calculated by Boltzmann mapping method.And the evolution trend of electron temperature and density with time and the influence of different pressures on its evolution are observed.?3?Based on the previous study of plasma characteristics.The deposition of graphene film on Ge substrate was induced by pulsed laser deposition,and the influence of process parameters was studied.It was found that a graphene film can be obtained only when the deposition temperature is 500°C or higher.However,due to the limitations of the experimental equipment,the temperature cannot be further increased.The obtained graphene film has poor uniformity and too small size.?4?The laser induced graphene?LIG?was studied,and the effects of laser power and different PI materials on LIG formation were explored.