Investigation Of The Photodetached Wave Packet Dynamics Of H~- Ion In Strong Field Near Surface

With the development of short pulse laser technology,preparation and detection the electronic wave packet in different systems have become possible in the experiments.The semiclassical closed orbit theory has become an essential tool to explain the photo-absorption phenomenon of atoms or molecules in strong fields due to its wide availability and clear physical picture.It has been proved to be an important bridge for connecting the classical theory with the quantum theory,and a typical example to study the conception of quantum chaos.This theory combined with the laser pulse technology can facilitate the study of wave packet dynamics,and the measurement of autocorrelation functions,etc.Since the autocorrelation function can reflect the revival phenomenon of the quantum wave packet,and is also one of the most important parameters than can be measured through pump-probe experiment,therefore,many researchers use the autocorrelation function to study the wave packet dynamics.In this paper,on the basis of the semiclassical closed orbit theory,we study the wave packet dynamic properties of the photodetached electron in strong field near surface through computing the autocorrelation functions of the system.Our work will provide some reference values for the experimental research on the wave packet dynamic properties of atoms or ions in the external fields near surface and in a microcavity.The main study of this thesis includes three aspects:1.By using the closed-orbit theory combined with the time-dependent perturbation theory,we study the wave packet dynamic properties of H~-ion in a gradient electric field.Especially we discuss the effect of laser pulse width,electric field strength and the electric field gradient on the autocorrelation function of H~-ion.It is demonstrated that when the laser pulse width is very short,the quantum wave packet revival phenomenon is significant.A series of sharp reviving peaks appear in the autocorrelation function.However,with the increase of laser pulse width,the quantum wave packet revival phenomenon becomes weakened.In addition,our study also suggests the background electric field strength and the electric field gradient can also have significant effects on the autocorrelation function.With the increase of background electric field strength and electric field gradient,the period of the detachedelectron's closed orbit gets shorter,the number of the revival peaks in the autocorrelation function is increased gradually,and the quantum wave packet revival phenomenon gets strengthened.2.The electron wave packet dynamic properties of H~-ion in a magnetic field near a surface has been studied.Firstly,we put forward an analytic formula for calculating the autocorrelation function of this system.Then we calculate and analyze the autocorrelation function in great detail.It is demonstrated that the quantum wave packet revival phenomenon is significant when the laser pulse width is far less than the period of the detached electron's closed orbit.As the pulse width is close to the period of the detached electron's closed orbit,the quantum wave packet revival phenomenon becomes weakened.When the laser pulse width is bigger than the period of the closed orbit of the detached electron,the adjacent revival peaks in the autocorrelation function begin to merge and the quantum revival phenomenon disappears.In addition,the magnetic field strength can also affect the autocorrelation function of this system.As the magnetic field strength is relatively small,the quantum wave packet revival phenomenon is weak.With the increase of the magnetic field strength,the number of the reviving peaks in the autocorrelation function becomes increased and the quantum wave packet revival phenomenon becomes significant.3.We study the electron wave packet dynamics photo-detached from H~-ion in a microcavity.An analytic formula for calculating the autocorrelation function of this system has been put forward,which can be written as a sum of modified Gaussian terms whether the wave packet is generated by a single-pulse laser or a double-pulse laser.Our calculation results suggest that the laser pulse width,the delayed time and the distance from the ion to the surface of the microcavity can have great impacts on the autocorrelation function of this system.In addition,we have studied the evolution and revival of the photodetached electron wave packet in the microcavity through the calculation of the time-dependent gaussian wave packet.We construct the time-dependent Gaussian wave packet based on the eigen-energy and eigen-wave function of the system.By taylor expansion the eigen-nergy of the system,we obtain the parameters of classical period and quantum revival time.With the analysis of the wave packet evolution characteristics,we find that the wave packet will change withthe evolution of the time.It can experience complete revival and part revival at different time.Through the analysis of the evolution characteristics of the wave function and the autocorrelation function,we find that different values of the initial position z0(the position that the wave packet begin to evolve after exciting)and momentum p0 will have significant effects on the evolution and revival of the wave packet.This paper is divided into five chapters.The first chapter is the introduction,which introduces the research significance,the domestic and overseas research status,the semiclassical closed-orbit theory,the dynamic evolution of the wave packet and the innovation points of this paper.In chapter two,by using the combination method of the time-dependent perturbation theory and the closed-orbit theory,we have studied the electronic wave packet dynamics photodetached from H~-ion in a gradient electric field.In chapter three,we research the electronic wave packet dynamics of H~-ion in a magnetic field near a surface.In chapter four,we research the electronic wave packet dynamics of H~-ion in a microcavity by a single-pulse laser or a double-pulse laser,and analyze the evolution and revival of the wave packet.Some conclusions and prospects are given in chapter five.