The measurement of 3s energy levels of atomic lithium

• Main Authors: Jwo-Sy Chen, 陳倬思
• Other Authors: Yi-Wei Liu
• Format: Others
• Language: en_US
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/35567323886192413729

碩士 === 國立清華大學 === 物理學系 === 95 === To determined the $3$s energy levels of lithium isotopes, a $735$ nm Ti:Sapphire laser is used to excite the ground state atomic lithium from a atomic beam system. The laser frequency is measured simultaneously by optical frquency comb, which gives the accuracy to $10^{-12}$ level. The excitation laser is stabilized by phase-locking to a specific comb line. The induced fluorescences spectra of $2$p-$2$s decay channel are fitted to a Voigt function with a Gaussian background to decide the transition line centers. The best signal-to-noise ratio of the transition spectrum is about $200$. The measured transition centers are $815\,618\,181.26(48)$ MHz and $815\,606 \,729.8(24)$ MHz for $^7$Li and $^6$Li $2$s-$3$s transitions respectively, which is improved by an order of magnitude for \,$^7$Li. However, The hyperfine structure constants, $93.73(48)$ MHz for \,$^7$Li and $36.0(35)$ MHz for \,$^6$Li, show the discrepancy with previous measurements \cite{Bushaw2003,Ewald2004}.