摘要
Almost all the atoms in the hyperfine sublevel F=4,m_(F)=0("clock level")of cesium ground state have been pumped out by using a laser diode tuned on the Cs-D2 line;and 15.2%population difference(|δoo|)which is more than two times better than what the traditional magnetical selecting state method could provide is found.This experimental result can be applied into building an optically pumped Cs beam frequency standard and better performance will be expected.