The Research Of Interaction And Deposition For Chromium Atoms In Laser Field

The research of nano-meter length transfer standard become more and more important in the nano-meter field. Direct writing atom lithography is a new technique in which resonant light is used to pattern an atomic beam and the nanostructures are formed when the atoms deposit on the substrate. Compared with the conventional optical lithography, the atom lithography technique in performance has potentially advantages. The process of atom lithography is based on two different types of interactional forces that can be used to manipulate neutral atoms by laser field, the atomic beam was collimated and the standing-wave field acts like an array of cylindrical lenses and can focus them onto the substrate and then form a nanometre structure, the spacing between the lines is predictably coincided with the half-wavelength of the optical standing-wave that was used as a light mask.This paper analyses the basic two different force, they are the spontaneous force that can be used to collimate the neutral atomic beam and the dipole force that can focus neutral atomic beam, at the same time the deposition simulation of chromium atoms in the standing wave was given in the paper.The main contents and originalities in this dissertation can be summarized as follows: (1) The dissipative force which chromium atom feels in the laser field was discussed in this paper and the simulated results shows that the atoms could be cooled in the low velocity range.At the same time, the distribution characteristics with different laser power and detunings of chromium atoms under dissipaticve force were discussed.(2) The characteristics of dipole force which chromium atoms feels in the standing wave were analysised. We find that the atoms formed regular distribution under the operation of potential and this distribution would be affected by laser power and detunings. Based on these analysis the compute model was set up which to describing the movement of singal atom under the dipole force by using Runge-Kutta arithmetic.(3) Based on the semi- classical theory, the spherical aberration, chromatic aberration and beam divergence in standing wave were discussed in this paper, the FWHM(Full Width of Half Maximum) and Contrast of stripe under these effects were discussed. At the same time, the effects of substrate position, the laser power and the beam waist are also analysed.