利用YAG激光抽运的染料激光器将钾原子由基态4S双光子共振激发到6S态,研究了钾原子4S-6S双光子共振三光子电离的电离谱与温度、激光强度的关系,发现电离流的强度随着温度的升高而增强,当温度在370℃附近时达到最大值,此时温度继续升高电离流强度减弱.在温度不变的情况下,电离流强度随着激光能量的增强而增强,当激光强度为4.5×10 5W/mm 2时到达最大值,继续增加激光强度,电离流强度趋于饱和.实验中观测到对应于6S-4P的自发辐射.

The ionization spectrum of potassium atom is investigated by 4 2S 1/2 6 2S 1/2 two photon resonant excitation. The resonant exciting laser wavelength is 728.4 nm. The ionization spectrum as a function of temperature and laser intensity are discussed. When the temperature of potassium vapor comes to 643 K, the ionization intensities reach the maximum. And the ionization intensities are saturated while laser intensity increased to 4.5×105 W/mm2. The spontaneous spectrum of the 6 2S 1/2 4 2P 1/2,3/2 is also observed.