中性钠原子在激光驻波场中的运动特性研究

The research of motorial characteristic of sodium atoms in standing wave field

基于半经典理论,分析了中性钠原子在激光驻波场中的受力特征,以此为基础分别对不同纵向运动速度和横向运动速度条件下中性钠原子的运动轨迹进行了仿真运算,得到了不同速度条件下中性钠原子的运动轨迹特征,基于累计算法进一步对不同速度条件下中性钠原子的沉积特性进行了仿真,当钠原子的纵向运动速度符合最可及速度(740m/s)时,纳米沉积条纹的半高宽为2.78nm,条纹对比度为38.5∶1,当纵向运动速度偏离最可及速度(350m/s)时,纳米沉积条纹的半高宽为29.1nm,其对比度下降为15∶1.而当中性钠原子的横向运动速度为0.12m/s(对应原子束发散角为0.15mrad)时,纳米沉积条纹的半高宽为4.2nm,条纹对比度为20∶1,当中性钠原子的横向运动速度为1.2m/s(对应原子束发散角为1.5mrad)时,纳米条纹呈现多峰结构,条纹质量恶化.

Direct write 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. The motion of sodium atoms in standing wave filed is discussed. Based on the semi-classical model,this paper analyses the motion equation of sodium atom in the laser standing wave field,and then gets the trajectory of the atoms in the standing wave field by analytical simulation for different longitudinal and transverse velocities. The simulative results show that the FWHM width of stripes was 2. 78 nm and the contrast was 38. 5∶ 1 for the optimal longitudinal velocity,while that of the stripes was 29. 1 nm and the contrast was 15∶ 1 for non-optimal longitudinal velocities. At the same time,the results show that the FWHM width of stripes was 4. 2 nm and the contrast was 20∶ 1 when the divergence of atomic beam was 0. 15 mrad. Whereas,the stripes presented Multipeaked configuration and the quality deteriorated with the divergence of atomic beam increased to 1. 5 mrad.