原子吸收光谱对碱金属原子蒸气密度与压强的测量方法  

Measurement of Atomic Number of Alkali Vapor and Pressure of Buffer Gas Based on Atomic Absorption

作　　者：郑慧婕 全伟[1] 刘翔 陈瑶[1] 陆吉玺[1] 

机构地区：[1]北京航空航天大学“惯性技术”重点实验室、“新型惯性仪表与导航系统技术”国防重点学科实验室,北京100191 [2]上海航天控制工程研究所,上海200233

出　　处：《光谱学与光谱分析》2015年第2期507-511,共5页Spectroscopy and Spectral Analysis

基　　金：国家自然基金委重大仪器专项(61227902);国家自然科学基金项目(61374210);SAST基金项目资助

摘　　要：利用SERF原子自旋效应能够实现高灵敏度的磁场测量,碱金属原子密度与缓冲气体压强是敏感表头碱金属气室的重要参数,需要精确地测量。提出一种应用原子吸收光谱对碱金属蒸气的原子密度与压强测量方法,通过扫描碱金属原子的吸收光谱,进行Lorentz线型拟合,经解算同时得到原子密度和压强,一次实验获得两个物理量。由于多普勒展宽和压力展宽主要受到碱金属气室温度和缓冲气体压强的影响,从这两个方面进行了仿真分析。结果表明,充入2amg缓冲气体时,313~513K温度范围内的Lorentz线型与Voigt线型计算的光子吸收截面积峰值的理论误差始终小于0.015%;缓冲气体压强高于0.6amg（393K）时,其峰值误差小于0.1%,表明该条件下多普勒展宽对吸收光谱的影响可以忽略,可用Lorentz线型拟合原子的吸收谱线。最后分析了该方法能够获得的理论分辨率以及激光器的功率波动、波长波动和气室温度波动对测量精度的影响,得出同等条件下温度波动的影响比其他两个因素高1~2个数量级。High sensitivitymagnetic measurementscanbe achieved by utilizing atomic spinmanipulation in the spin-exchange-relax- ation-free （SERF） regime, which uses an alkali cell as a sensing element. The atomic number density of the alkali vapor and the pressure of the buffer gasare among the most important parameters of the cell andrequire accurate measurement. A method has been proposed and developedto measure the atomic number density and the pressure based on absorption spectroscopy, by sweep- ing the absorption line and fittingthe experiment data with a Lorentzian profile to obtainboth parameters. Due to Doppler broade- ning and pressure broadening, which is mainly dominated by the temperature of the cell and the pressure of buffer gas respective- ly, this work demonstrates a simulation of the errorbetween the peaks of the Lorentzian profile and the Voigt profile caused by bothfactors. The results indicates that the Doppler broadening contribution is insignificantwith an error less than 0. 015 M at 3 1 3 ~513 K for a 4He density of 2 amg, and an error of 0. 1% in the presence of 0. 6~5 amg at 393 K. We conclude that the Doppler broadening could be ignored under above conditions, and that the Lorentzianprofile is suitably applied to fit the absorp- tion spectrumobtainingboth parameters simultaneously. In addition we discuss the resolution and the instability due to thelight source, wavelength and the temperature of the cell We find that the cell temperature, whose uncertainty is two orders of magni- tude larger than the instability of the light source and the wavelength, is one of the main factors which contributes to the error.

关 键 词：原子吸收光谱 原子密度 气体压强 Lorentz线型 

分 类 号：TH744[机械工程—光学工程]