COHERENT WAVE MIXING PROCESS BY USING METASTABLE ATOMS

In PbCI₂ vapor under the mutual interaction of two laser beams with wavelengths at λ₁=266nm and λ₂=280.2nm ( or 282.3nm), a strong coherent emission at 405.8nm is generated, which corresponds to transition between states 6p7s ³p⁰₁ and 6p^{2 3}p₂ in atomic Pb. The dependences of its intensity I_405.8 on the power and detuning of λ₂ are measured. The results show that it is caused by a four-wave mixing process in Pb, in which the initial state is a metastable state, 6p^{2 3}p₂.