Study On Regulaiton Of Photo-Detachment Of H~-near A Surface By Strong Fields

With the development of photo-detachment microscopy and surface physical, muchattention has been paid to the photo-detachment of the atom or the anion system in theexternal fields and surface. In this thesis, we use semi-classical theory to study the_photo-detachment of Hin electric and magnetic fields near surfaces. It is found that thephoto-detachment cross section of H-can be influenced greatly by the magnetic field strength,electric field strength and electric field direction, dielectric constant and ion-surface distance.And at the same time, the magnetic field strength, electric field strength, the energy ofdetached electron, laser polarization direction and ion-surface distance can vastly influencethe detached electron flux distribution.Firstly, using the semi-classical closed orbit theory, we study the photo-detachment ofH-in the magnetic field near a dielectric surface. The photo-detachment cross section of thissystem has also been derived and calculated. It is found that the photo-detachment crosssection is not only related to the magnetic field strength, but also depends on the dielectricconstant. Therefore we can control the photo-detachment of anion by changing the magneticfield strength and the dielectric constant.Secondly, using the semi-classical closed orbit theory, we study the photo-detachmentof H-in parallel electric and magnetic fields near a metal surface.(1) We study the magnetic field effect in the photo-detachment of anion in the electric fieldnear a metal surface with a given ion-surface distance and electric field strength. The resultsshow that the magnetic field can produce significant effect on the photo-detachment of anionnear metal surface. Besides the closed orbits previously found by Du et al for the H-in theelectric field near a metal surface, some additional closed orbits are produced due to theeffect of magnetic field. With the increase of the number of closed orbits, the oscillations inthe cross section become more and more complicated.(2) The influence of electric field on the photo-detachment of H-in magnetic field near ametal surface with a given ion-surface distance and magnetic field strength is studied byusing the semi-classical closed orbit theory. It is found that the photo-detachment of H-is notonly related to the electric field strength but also to the electric field direction. If the electricfield F is along the+z axis and no matter what value of the F is, it all can strengthen the oscillation in the photo-detachment cross section. However, if the electric field is along the-zaxis, the situation becomes much more complicated. In this case, there are two kinds of orbits,including up orbits and down orbits. The photo-detachment cross sections become muchmore complex.At last, the photo-detachment of H-in the electric and magnetic field near a metalsurface with a semi-classical open theory of photo-detachment microscopy have been studiedand the relations between the electron flux distribution and classical trajectories also havebeen revealed.(1) We study the electron flux distribution of H-in the electric field near a metal surface. Theelectron is drawn toward a position-sensitive detector because of the electric field and themetal surface. Two classical paths lead from the ion to any point in the classically allowedregion on the detector, and waves traveling along these two paths produce an interferencepattern. The interference pattern is not only related to the electron energy and the electricfield strength, but also related to the ion-surface distance. Besides, the laser polarizationdirection also has a great influence on the electron flux distribution.(2) We study the photo-detachment of H-in the magnetic field near a metal surface. Duringthe photo-detachment, the electron is photo-detached by a laser and the electron is drawntoward a position-sensitive detector and the electron flux distribution is measured as afunction of position. Many classical paths lead from the ion to any point in the classicallyallowed region on the detector, and waves traveling along these paths produce an interferencepattern. The detached electron flux distribution is not only related to the magnetic fieldstrength but also to the energy of detached electron. Therefore we can change thephoto-detachment of anion by controlling the magnetic field strength and the energy ofdetached electron.Our study will provide a new understanding on photo-detachment cross section andphoto-detachment microscopy of anion in external fields and surfaces. And can be used toguide the future experiment research on the anion photo-detachment microscopy. Our resultsare of great significance to enrich and develop this theory and also have important applicationprospect on plasma physics, surface science, fusion, laser isotope separation and otherhigh-tech areas.