摘要
We report absolute frequency measurements of molecular iodine P(46) 5-4 a 1 , a 10 , and a 15 hyperfine transitions at 647 nm with a fiber-based frequency comb. The light source is based on a Littrow-type external-cavity diode laser. A frequency stability of 5 × 10 −12 at a 200 s integration time is achieved when the light source is stabilized to the P(46) 5-4 a 15 line. The pressure shift is determined to be −8.37 kHz∕Pa. Our determination of the line centers reached a precision of 21 kHz. The light source can serve as a reference laser for lithium spectroscopy (2S → 3P).