Effect Of Surface Structure On Its Luminescence Characteristics Of CsI(Na) Crystal

As an important inorganic halide scintillator,CsI(Na)crystal has been widely used in industrial exploration,space physics and other fields.As a core component of scintillator detector,CsI(Na)crystal has attracted widespread attention.The research of CsI(Na)crystal is also very important at home and abroad.Because CsI(Na)crystals have been widely used as scintillators,the study of luminescent properties of CsI(Na)crystals has become an important research direction.In this paper,the influence of surface structure of CsI(Na)crystal on its luminescent properties has been studied.In this paper,the surface structure of scintillator is analyzed by experiment and simulation.The experiments are divided into two parts,one is the influence of deliquescence of CsI(Na)crystal on its luminescent properties,the other is the influence of surface of micro-nanofabricated CsI(Na)crystal on its luminescent properties.The deliquescence experiments of CsI(Na)crystals confirmed that with the increase of exposure time of unpackaged CsI(Na)crystals to air,their luminescence efficiency was worse and compared with the follow-up simulation experiments.On the other hand,the experimental results of micro-nanofabricated CsI(Na)crystal surface show that the addition of photonic crystals on the surface of CsI(Na)crystal makes the output of scintillator increase significantly.At the same time,the optimum particle size of photonic crystal PS spheres is verified to be 500 nm.The extraction efficiency can reach up to 15%.In terms of simulation,the effect of adsorption of hydrogen peroxide on the luminescent properties of CsI(Na)crystal was studied by first-principles calculation.We have studied the changes of band structure,electron density and optical properties caused by the adsorption of hydrogen peroxide on CsI(Na)(010)surface.The generalized gradient approximation(GGA)is used to describe the exchange potential and correlation potential between electrons.The results show that the bandwidth of hydrogen peroxide decreases and three new peaks of valence band appear after it is adsorbed on CsI(Na)(010)surface.At the same radiation intensity,the photoyield of the adsorbed surface is slightly increased from the perspective of electronic structure.At the same time,both absorption coefficient and reflection coefficient decrease greatly,which indicates that the absorption of light by surface decreases greatly.From the simulation point of view,combined with electronic structure and optical properties,it can be concluded that the absorption of hydrogen peroxide on CsI(Na)(010)surface will greatly reduce the luminescence efficiency of CsI(Na)(010).These calculations confirm our experimental results and show that the absorption of hydrogen peroxide greatly reduces the luminescence efficiency of CsI(Na)crystal.Through the above experiments and simulations,it can be seen that the surface structure of CsI(Na)has a great influence on its luminescent properties.At the same time,the first-principles calculation is used to explain the reason why the deliquescence decreases the luminous efficiency of scintillators.The enhancement effect of photonic crystal PS spheres on the luminescence efficiency of scintillators is also verified.The research on the surface of scintillator crystal still needs further study,so as to further improve the luminous efficiency of scintillator and reduce the energy resolution of scintillator detector.