我們使用交叉原子束法測量鋰原子6,7Li的D1譜線的超精細結構和同位素偏移。我們的光譜雷射是波長為670.9 nm的外腔式二極體雷射，並將雷射用Pound-Drever-Hall技術穩頻在Fabry-Perot干涉共振腔上，並且藉由改變共振腔腔長掃描鋰原子光譜。參考頻率雷射則是鎖在碘分子的譜線上。利用光電倍增管偵測雷射激發的原子螢光訊號，並記錄光譜雷射和參考雷射的拍頻做為訊號的頻率。

我們的實驗結果6,7Li在基態2S1/2的超精細結構分裂為228.198 (12) MHz和 803.495 (8) MHz，在第一激發態2P1/2超精細結構分裂為26.108 (9) MHz和 91.873 (5) MHz。而6,7Li 之間的同位素偏移為10533.800 (15) MHz。我們的量測釐清了不同團隊量測結果的爭議，並且與大部分的理論預測相符。

We have precisely measured the hyperfine intervals and isotope shift of D1 lines of atomic lithium 6,7Li in a collimated atomic beam. The spectroscopy laser, an external-cavity diode laser (ECDL) with wavelength 670.9 nm, which is locked to a Fabry-Perot cavity by Pound-Drever-Hall technique, scans the spectrums by changing the cavity length. The reference laser is locked to molecular iodine transition. The laser-induced fluorescence signal is detected by photomultiplier, and the beat frequency between spectroscopy laser and reference laser is recorded.

The results of 6,7Li for 2S1/2 hyperfine interval are 228.198 (12) MHz and 803.495(8) MHz. For 2P1/2 hyperfine interval, they are 26.108(9) MHz and 91.873(5) MHz. The isotope shift is 10533.800(15) MHz. Our results resolve the discrepancies between former measurements, and are consistent with most theoretical calculations.

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