中文摘要：

囚禁汞离子的光微波双共振实验是开展汞离子微波频标的实验基础。二级Zeeman效应是影响频率稳定度和磁场效应的重要因素之一。利用光学微波双共振方法测量了囚禁^199Hg^＋离子基态Zeeman分裂。通过减小微波扫描的频率范围，得到钟跃迁频率和谱线线宽。采用磁屏蔽材料（坡莫合金）对离子阱囚禁区域的磁场进行屏蔽。使得囚禁汞离子的钟跃迁谱线的线宽减小到1．5Hz。相对于无磁场屏蔽时，钟跃迁频率减小13．5Hz，并利用二级Zeeman效应估算出磁屏蔽后离子囚禁区域磁场大小为0．1高斯。

英文摘要：

The experiment of optical-microwave double-resonance in trapped mercury is the basis for the research of mercury ion microwave frequency standard. The second-order Zeeman effect is one of the important factor affecting frequency stability and the magnetic field effect. The Zeeman spectrum of ground state of trapped ^199Hg^＋ ion was measured by the method of optical-microwave double-resonance. The clock transition frequency and linewidth of the clock transition line were obtained by scanning the microwave frequency in a narrow region. The magnetic field in trapping area was shielded by the materials of permalloy. The linewidth of the clock transition line is decreased to about 1.5 Hz. Comparing the clock transition frequency without magnetic shielding, the clock transition frequency of magnetic shielding decreases 13.5 Hz. According to the second-order Zeeman effect, it＇s calculated that the magnetic field of trapped region is about 0.1 Guass.