Measurement of Atomic Number of Alkali Vapor and Pressure of Buffer Gas Based on Atomic Absorption
ZHENG Hui-jie1, QUAN Wei1*, LIU Xiang2, CHEN Yao1, LU Ji-xi1
1. Science and Technology on Inertial Laboratory, Fundamental Science on Novel Instrument & Navigation System Technology Laboratory, Beihang University, Beijing 100191, China 2. Shanghai Aerospace Control Engineering Research Institute, Shanghai 200233, China
Abstract：High sensitivitymagnetic measurementscanbe achieved by utilizing atomic spinmanipulation in the spin-exchange-relaxation-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 sweeping the absorption line and fittingthe experiment data with a Lorentzian profile to obtainboth parameters. Due to Doppler broadening and pressure broadening, which is mainly dominated by the temperature of the cell and the pressure of buffer gas respectively, 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% at 313～513 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 absorption 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 magnitude larger than the instability of the light source and the wavelength, is one of the main factors which contributes to the error.
Key words：Atomic absorption spectrometry;Atomic number density;Pressure of buffer gas;Lorentz profile
郑慧婕1，全 伟1*，刘 翔2，陈 瑶1，陆吉玺1 . 原子吸收光谱对碱金属原子蒸气密度与压强的测量方法 [J]. 光谱学与光谱分析, 2015, 35(02): 507-511.
ZHENG Hui-jie1, QUAN Wei1*, LIU Xiang2, CHEN Yao1, LU Ji-xi1 . Measurement of Atomic Number of Alkali Vapor and Pressure of Buffer Gas Based on Atomic Absorption . SPECTROSCOPY AND SPECTRAL ANALYSIS, 2015, 35(02): 507-511.
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