【作者】 王强；

【导师】 印建平；

【作者基本信息】 华东师范大学 ， 光学， 2018， 硕士

【摘要】 冷分子领域经过二十年的发展,取得了很多令人瞩目的成就,并在物理、化学等诸多学科中有非常重要的应用。一系列制备和操控冷分子的技术也应运而生,例如分子的静电速度滤波、斯塔克减速、塞曼减速、缓冲气体冷却和光缔合等等。本文主要研究了冷分子的制备和操控。文中首先介绍了一种对极性分子进行表面速度滤波、聚束和存储的组合方案。该方案包含三部分,分别是静电速度滤波器、聚束器和存储环。射流分子束经过静电速度滤波后变为慢速分子束。然后慢速分子束的速度分布被由一列电极组成的聚束器压窄。最后拥有窄速度分布的慢速分子束被存储起来。以ND₃分子为例,我们理论上分析了该方案的可行性,并采用数值模拟进行了验证。结果显示,冷分子束可以从分子热源产生,被装载进存储环后可以飞行10圈。我们的方案集冷分子的制备和存储于一体,为基础研究提供了新的契机,并在量子信息科学和冷碰撞等领域有许多有趣的应用。接着文中提出了一种提高极性分子聚束效率的方案。静电聚束器在某些位置存在电场缺陷,导致分子在此处横向发散,分子损失较多,聚束效率较低。在静电聚束器的基础上,再施加静磁场,增强对分子的横向束缚,就可以减少分子损失,从而提高聚束效率。我们采用永磁体NdFe35产生静磁场,其产生的磁阱深度高达0.5特斯拉。OH自由基的蒙特卡罗模拟结果表明,在静电场与静磁场的复合场中,聚束15级后的效率提升为原来的2.5倍。更多还原

【Abstract】 With the developments of cold molecules in the past two decades,remarkable achievements have been made,and a lot of very important applications can be used in many fields,such as physics,chemistry,and so on.Many approaches have been developed to produce and control molecules,such as electrostatic velocity filtering,Stark deceleration,Zeeman deceleration,buffer gas cooling,photoassciation,and so on.This paper mainly studies the production and control of cold molecules.A scheme of surface manipulation and control of polar molecules is proposed,which combines three tools of electrostatic velocity filtering,bunching and storing.In the scheme a slow molecular beam is produced from an effusive beam by surface velocity filtering.Then the velocity spread of the slow molecular beam is compressed by a buncher consisted of a series of electrodes.Following that the molecular beam with a narrow velocity spread is stored in a storage ring.Using ND₃ molecule as a tester,the feasibility of our scheme is analyzed theoretically and verified via numerical simulations that cover all the three manipulation processes.The results show that cold molecular samples can be prepared from a thermal gas reservoir and can be stored in the storage ring with more than 10 round trips.Our combined scheme facilitates the production and manipulation of polar molecules,offering new opportunities for basic researches and intriguing applications such as quantum information science and cold collisions.Next,a new scheme of a buncher which can improve the efficiency of bunching is proposed.Because the electrostatic buncher has a defect in some positions,which cause the transverse defocusing of the molecules,lots of molecules loss and the bunching efficiency is low.When combining the electric field with the magnetic field which can transversely focus the molecules,the loss of the molecules can be reduced and the bunching efficiency can be improved.Permanent magnet NdFe35 is used to produce the magnetostatic field,which has a magnetic trap of 0.5 Tesla.With the Monte Carlo simulation of OH radical,the bunching efficiency after 15 stages increases to 2.5 times in the combined electric and magnetic fields.更多还原