中文摘要：

在己有实验的基础上,提出了由双光子共振非简并四波混频和碰撞再构非简并四波混频组成用于研究原子碰撞效应的双非简并四波混频理论,分析了缓冲气压、温度、共振失谐和碰撞展宽系数对双非简并四波混频谱线的影响.在由基态、中间态和激发态组成的级联三能级系统中,双非简并四波混频可同时研究碰撞引起的激发态谱线展宽和碰撞引起的中间态能级再分布现象.与测量纵向弛豫碰撞展宽的传统实验方法不同,本文方法是一种纯光学的相干测量技术,可以同时测量激发态与基态间的横向弛豫Γ20和中间态与基态间的横向弛豫Γ21的碰撞展宽.

英文摘要：

In recent years,the collisional redistribution of radiation and collision-induced broadening of Rydberg atomic spectral lines by buffer gas perturbation have aroused the renewed interest.Rydberg atoms having a large dipole moment and long lifetime can interact with each other coherently for relatively long time,which makes them a potential candidate for quantum information processing.Besides,collisional redistribution has an important potential application in laser cooling and trapping.Based on previous experimental data,in this paper,two-nondegenerate four-wave mixing（NFWM） for studying atom collision,composed of two-photon resonant NFWM and collisional redistribution NFWM,is reported.The spectrum variation of the two-NFWM affected by the pressure,temperature,detuning and collision-broadening rate coefficient is analyzed.The principle of two-NFWM involving three incident beams is explained as follows.Consider two-NFWM in a｜0〉｜1〉｜2 cascade three-level system,where states between ｜0〉 and ｜1〉 and between ｜1〉 and 2 are coupled by resonant frequencies Ω1 and Ω2,respectively.Beam 1 with frequency ω1 propagates along the direction opposite to the direction of beam 2,beams 2 and 2＇ have the same frequency ω2,and between their directions there exists a small angle.Assuming that ω1≈Ω1 and ω2≈Ω2 so that ω1 drives the transition from ｜0〉 to ｜1〉 while ω2 drives the transition from ｜1 〉to 2,the simultaneous interactions of atoms with beams 1 and 2 will induce atomic coherence between ｜0 〉and ｜2〉 through two-photon excitation.This coherence is probed by beam 2＇,and as a result a two-photon resonant NFWM signal of frequency ω1 is generated in the direction almost opposite to the direction of beam 2＇.To avoid strong absorption at the resonant frequency of transition from ｜0〉 to ｜1〉,here the wavelength of beaml is detuned from the exact resonance.An atom population of level ｜1〉 caused by collisional redistribution can be induced when a certain buffer g