An Investigation On The Characteristics Of Laser Inducedplasma Of Liquid Matrix

Due to the development of short pulse laser and laser technology,the laser induced plasma is extensively applied in the fields of laser microsurgery and trace elements analysis,film deposition production technology.The further study of the property of the laser induced plasma leads to the development of the correlated laser spectroscopy technique and its application.Laser induced breakdown spectroscopy(LIBS)which is one of the typical sample related to laser induced plasma,is known as the most potential spectroscopy analysis technique.Laser induced plasma is an unstable plasma;its formation is a complex process which depends on many factors.Excepter for the laser related parameters and the properties of the buffer gas,the physical and chemical property of the matrix has important effect on the characteristics of laser induced plasma.At present,the micro interaction mechanism between the laser and liquid sample,the production and its evolution property of the laser induced liquid matrix plasma,were less investigated and need to further experimental and theoretical research.The plasma produced by pulse laser irradiation of the liquid sample is called as low temperature micro plasma.The atoms and molecule at different electronic states in laser induced plasma will produce measurable emission spectrum(Laser induced plasma spectrum,LIPS).Investigation on the temporal evolution dynamics of the time resolved emission spectra of different elements in plasma can effectively display the production mechanism and evolution properties of the laser induced plasma.The electronic temperature and electron density are the most important physical parameters to reflect the basic properties of the plasma,and can be measured by the measured spectral line intensities of different elements in the plasma.This dissertation is mainly to study the temporal evolution characteristics of the emission spectra and electronic temperature and electronic density of the plasma produced by laser ablation of liquid matrix.The Cr(359.42 nm,360.641 nm,425.534 nm,427.53 nm,429.087 nm,520.751 nm and 520.992nm)spectral line integrated intensities were measured by the time resolved spectrum measurement system.The electron temperature and electron density of the plasma were obtained by the Boltzmann slope method and the Saha-in accordance with leather(Saha-Eggert)formula approach respectively.The evolution property of electron temperature and electron density of the plasma was concluded by the experiment measured results mentioned above.