鉈原子在基本的原子物理裡面扮演很重要的角色，例如在宇稱不守恆的理論或是電子的電偶極理論都有運用到鉈原子的研究。對於鉈原子結構的詳細了解可以增進我們對於理論和實驗結果的相互比較，因此，對於鉈原子的超精細能階結構和同位素分裂的研究，將能給許多的理論提供重要的依據。

我們將Ti:sapphire雷射所輸出的755 nm雷射光經過倍頻共振腔，產生波長為377 nm的雷射光，並用此來激發鉈原子在6P1/2到7S1/2能階躍遷光譜。為減少都卜勒效應，將鉈原子加熱後產生的原子束和激發雷射垂直重疊，在400oC時可測量到譜線寬度為32MHz，和理論計算相當接近，並且分析各個躍遷光譜可得到Isotope-shift為1659.3MHz。

未來的工作除了再使用第二個相同的倍頻雷射光來激發鉈原子從6P3/2到6D5/2，在量測光譜的改進上，也將使用飛秒光頻梳系統來測量光譜的絕對頻率，可以對於各個躍遷能階做更準確的量測。

Atomic thallium plays an important part in the test of fundamental atomic physics, such as parity nonconservation (PNC) and electron's electrical dipole moment (EDM). The detail understandings of the atomic structure of thallium can further improve the comparison between the experimental and theoretical results. Therefore, the measurement of the hyperfine splitting and isotope shift offer several important informations in such understandings.

The 755-nm Ti:sapphire laser is frequency-doubled in LBO crystal with a enhance ring cavity. And we use the second harmonic signal at 377 nm to pump the thallium energy level from 6P1/2 to 7S1/2. In order to reduce the Doppler effect, the laser light must overlaps perpendicularly the thallium atomic beam. The linewidth of Tl 6P1/2 →7S1/2 transition is measured as 32 MHz. It matches the theoretical prediction. The isotope-shift of Tl 6P1/2 →7S1/2 transition is 1659.3 MHz

In the future, we will use the second laser source with the same setup to pump the thallium transition from 6P3/2 to 6D5/2 and use the femtosecond comb system to measure the absolute frequency of the thallium transitions.

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