Saturation Spectroscopy Based On Metastable ~7Li~+ Beam

Precision spectroscopy measurement in few-body atomic systems played an important role in verifying fundamental physics and determining the fundamental physical constants.Lithium ion(Li+)is one of the simplest helium-like few-body atomic systems,and its energy levels can be calculated with high precision using quantum electrodynamics(QED)theory since it has only two electrons outside the nucleus.In QED theory,electromagnetic interaction is characterized by fine-structure constant a.So,a combination of the precision calculation and the precision measurement of fine structure splittings of Li+ can verify the QED theory and determine the fine-structure constant a.Currently,the accuracy of experimental results of fine structure spectroscopy of Li+is still far below that of the theoretical calculation,an improvement of the accuracy of experimental measurement is urgently needed.In addition,despite the fact that most of previous experiments were based on Li+ beam,find:ing another way to reduce undesired influence of factors such as Doppler effect on spectroscopy measurements has become one of the major subjects for higher precision spectroscopy measurement of Li+.This thesis introduces a precision spectroscopy measurement of 'Li+based on metastable ion beam,and also studied the deceleration of Li+beam in preparation for higher precision spectroscopy measurement of trapped Li+.The topics covered by this thesis are categorized as follow:1.An apparatus for Saturated fluorescence spectroscopy measurement based on metastable Li+beam was built and optimized.We designed and built an ion beam source of Li+which contains>1%metastable Li+and can provide stable ion beam continuously for over 250 h;Based on the ion beam source,a saturated fluorescence spectroscopy measurement system was built,which realized the switch between two transition measurements and obtained Lamb dip signals without Doppler background.2.The fine and hyperfine structure spectroscopy of 2 3S and 2 3P of7Li+was measured on metastable ion beam,and the results with uncertainties of below 100 kHz was achieved.The measured fine and hyperfine structure splittings of 2 3P has an accuracy of 5-10 times higher than previous experiment values.3.The Li+beam was decelerated by a deceleration apparatus after the spectroscopy measurements.The deceleration apparatus contains a drift tube,an Einzel lens and a curved quadrupole,with which,an ion beam with kinetic energy of below 1 eV was obtained.