从光化学锂同位素分离实验研究的需求出发，基于其分离条件，提出了一种测量锂同位素比率的方法。该方法利用锂原子蒸气对探测光吸收峰的峰值来计算锂的同位素比率，避开了测量原子密度时所需的吸收信号频率定标与光强随频率变化积分中积分限的选择问题。该方法还根据锂同位素吸收谱的特殊性采用具有较强吸收效应的6 Li的D2线对应的吸收峰峰值，可在原子蒸气中6 Li含量较低时提高对比率的测量精度。设计并搭建了实验装置，对该方法进行了测试。同一条件下所测得的同位素比率相对标准偏差小于1％，表明该方法对光化学分离方法中锂同位素比率相对变化是敏感的。这意味着该方法可作为以原子蒸气为分离介质的激光锂同位素分离研究的诊断手段。%A method for measuring the isotope ratio in a photo-chemical lithium isotope separation process based on separation conditions was proposed . Instead of doing integration around the absorption peaks ,which was often conducted in calculating the isotope ratio from experimental curves , the peak’ s values were used to compute the isotope ratio of the lithium .The advantage of this procedure is that the complicated scaling operation for experimental curves can be avoided .The use of D2 line of 6 Li with stronger absorption effect can help to improve the measurement precision w hen the content of 6 Li in atomic vapor is low .An experimental setup was built and tested .In one experimental condition the relative standard deviation of the measured isotope ratio is less than 1% ,w hich show s that the method is sensitive to the change of the isotope ratio in a photo-chemical lithium isotope separation process .It means that the method is applicable as a diagnostic tool in the study of lithium atomic vapor laser isotope separation .
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