We report the precision measurement of the absolute frequencies, hyperfine splitting, and 2P fine structure splitting in cold atoms of ^{6}Li. Using the stabilized optical frequency comb and developed heterodyne detection technique, the photon shot-noise limited optical spectroscopy is achieved. The measurement of absolute frequencies of D_{1} lines is reached with an uncertainty of about 1 kHz, which is 1 order of magnitude more accurate than previous measurements. The hyperfine splitting of the D_{1} line and 2P fine structure splitting of ^{6}Li are 26.103 1 (14) and 10 052.780 4 (18) MHz, respectively, in agreement with recent theoretical calculations. Our results could provide a benchmark to test the theory at the higher precision and help to resolve large discrepancies among previous experiments.

中文翻译：

---

具有khz级不确定性的^ {6} Li D线的绝对频率测量。

我们报告了^ {6} Li的冷原子中绝对频率，超精细分裂和2P精细结构分裂的精确测量。使用稳定的光频率梳和先进的外差检测技术，可以实现光子散粒噪声受限的光谱学。D_ {1}线的绝对频率的测量结果的不确定性约为1 kHz，这比以前的测量结果精确1个数量级。与最近的理论计算相一致，D_ {1}线的超精细分裂和^ {6} Li的2P精细结构分裂分别为26.103 1（14）和10 052.780 4（18）MHz。我们的结果可以提供一个基准，以更高的精度测试该理论，并有助于解决以前的实验之间的巨大差异。