一种测量弱吸收条件下锂同位素比率的新方法
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摘要
在激光化学法锂同位素分离工作中,需对锂原子蒸汽密度进行实时监测。通过同位素比率的数值分析可提供分离实验中诸如激光功率、化学反应区温度、压强以及光化学反应时间等参数的优化依据。吸收光谱法可快速准确地测量非弱吸收条件下的锂同位素比率。对于低锂原子蒸汽密度的弱吸收条件,受示波器的分辨极限和存储时舍入误差的影响,不能得到准确有效的同位素比率数值。为了克服实验测量上存在的弱点,提出了一种基于差分电路采集信号的高分辨率高精度的研究方法,有效解决了弱吸收条件下的同位素比率测量问题。将该方法应用于天然锂进行了测试,得到的锂同位素比率为12.37±0.56。该方法对于采用吸收光谱法测量同位素比率具有通用性,也可在其他类似分离工作中应用。
During the work of photo-chemical lithium isotope separation,the density of lithium vapor needs real-time monitoring.The laser power,reaction temperature,pressure and time parameters of separation were optimized by analysis of isotope ratio.The lithium isotope ratio under non-weak absorption conditions can be quickly and accurately measured by absorption spectroscopy.Under weak absorption conditions,isotope ratio can not be accurately measured because of round-off error and resolving limit of the oscilloscope.In order to solve the problems in lithium isotope ratio measurements,a high resolution and precision signal acquisition method based on differential circuit was proposed.The ratio of natural materials was measured by using this method,and the result is 12.37±0.56.This method can be commonly used in isotope ratio measurement by absorption spectroscopy and can also be applied in other similar separation work.
During the work of photo-chemical lithium isotope separation,the density of lithium vapor needs real-time monitoring.The laser power,reaction temperature,pressure and time parameters of separation were optimized by analysis of isotope ratio.The lithium isotope ratio under non-weak absorption conditions can be quickly and accurately measured by absorption spectroscopy.Under weak absorption conditions,isotope ratio can not be accurately measured because of round-off error and resolving limit of the oscilloscope.In order to solve the problems in lithium isotope ratio measurements,a high resolution and precision signal acquisition method based on differential circuit was proposed.The ratio of natural materials was measured by using this method,and the result is 12.37±0.56.This method can be commonly used in isotope ratio measurement by absorption spectroscopy and can also be applied in other similar separation work.
引文
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[2]格里申ВК,格拉祖诺夫МГ,阿拉克洛夫АГ,等.锂的性质[M].如镜,译.北京:中国工业出版社,1966.
[3]LEWIS G N,MACDONALD R T.The separation of lithium isotopes[J].J Am Chem Soc,1936,58:2 519-2 514.
[4]金建南,王全基,孟明礼,等.用开链冠醚PAIV溶剂萃取分离锂同位素[J].四川大学学报:自然科学版,1999,36(5):903-906.JIN Jiannan,WANG Quanji,MENG Mingli,et al.The lithium isotope separation by solvent extraction using open chain crown ether paiv as complexing agent[J].Journal of Sichuan University:Natural Science Edition,1999,36(5):903-906(in Chinese).
[5]陈耀焕.溶剂萃取分离锂同位素概况[J].稀有金属,1983(4):79-87.CHEN Yaohuan.Solvent extraction separation of lithium isotopes overview[J].Chinese Journal of Rare Metals,1983(4):79-87(in Chinese).
[6]李廷伍.化学交换法分离锂同位素[J].原子能科学技术,1990,24(2):87-90.LI Tingwu.Lithium isotope separation by chemical exchange method[J].Atomic Energy Science and Technology,1990,24(2):87-90(in Chinese).
[7]唐柯鸿.激光光化学法同位素分离理论研究[D].北京:清华大学,2010.
[8]BOKHAN P A,BUCHANOV V V,ZAKREVSKII D E,et al.Current trends in laser separation of isotopes in monatomic vapors[J].Journal of Russian Laser Research,2003,24(2):159-167.
[9]BOKHAN P A,BUCHAOV V V,FATEEV N V,et al.Laser isotope separation in atomic vapor[R].Weinheim:WILEY-VCH VerlagGmbH&Co.KGaA,2006.
[10]MYERS E G,MURNICK D E,SOFTKY W R.Isotope selective laser enhancement of the Li+H2reaction[J].Appl Phys B,1987,43(4):247-251.
[11]瞿定荣,宋增云,王立军,等.基于光化学锂同位素分离条件的同位素比率测量[J].原子能科学技术,2014,48(5):792-796.QU Dingrong,SONG Zengyun,WANG Lijun,et al.Measurement on isotope ratio in process of photo-chemical lithium isotope separation[J].Atomic Energy Science and Technology,2014,48(5):792-796(in Chinese).