Study of characteristic role of lower lying energy levels in optical relaxation processes

根据晶体、液体和气体的状态不同，有多种光学驰豫过程。这些过程被简单地理解为电子-晶格相互作用的结果。但是，我们几乎不知道控制光学过程的主要物理常数。在这种情况下，我们只假设声子结构对凝聚态中弛豫过程的影响，然后我们试图抓住激发剂的哪种声子制造作用来松弛激发电子态，特别是在染料/聚乙烯醇等无定形基质体系中。另一方面，四波混频是探测探测分子环境条件的最通用和最灵敏的方法之一，因为它可以检测到紫外光的级数的差异。首先，我们用单色仪测量了来自碳化硅热源的单色化光调谐到OH伸缩模的振动能后，在红外辐射下的相位驰豫时间T2。在这种情况下，样品是以磺基罗丹明640和聚乙烯醇为基质，样品温度为4.2K，在本实验中，我们没有检测到红外光打开或关闭时T2的变化。由于碳化硅源的强度太弱，导致对准非常困难，所以这个实验并不是很完整。接下来，我们利用Mira-OPO闲置光作为激发红外光，其波长为2.7微米，脉冲宽度约为120飞秒。在这种情况下，T2在照射空闲光之前被明显地减少到它的一半。但现在我们还不能理解这是有意义的微热效应，因为样品温度可能只是简单地升高了。无论如何，我们现在正在继续进行更精确的实验。

There are many kinds of optical relaxation processes according to the states of crystals, liquids and gasses. These processes are understood as the results of electron-lattice interaction briefly. But, we do not almost know main physical constants to control the optical processes. In that case we only suppose phonon structures affecting the influences to the relaxation processes in condensed matters.Then we have attempted to catch what kinds of phonon making role of activator to relax the excited electron states, in particular, in the system of amorphous matrix such as dye/polyvinylalcohol. On the other hand, four-wave mixing is one of the most versatile and sensitive methods to detect the environmental condition of the probe molecular since it can detect the difference of the order of ueV.At first, we have performed to detect the phase relaxation time T2 under irradiating IR radiation which was monochrolized light tuned to the vibrational energy of OH stretching mode from SiC thermal source by using monochrometor. In this case, sample was sulfurohdamine 640 and PVA as matrix and the sample temperature was 4.2 K. In this experiment, we have not been able to detect the change of T2 when the IR light was on or off. This experiment has been not so complete because the intensity of SiC source was so weak that alignment was very difficult. Now we attempting this experiment.Next, we employed Mira-OPO idler light as an exciting IR light whose wavelength was 2.7um and pulse duration was about 120 fs. In this case, T2 was clearly reduced into the half of it before irradiating idler light. But now we can not understand that this is meaningful micro-thermal effect because sample temperature might have raised simply.Anyway, we are now continuing the more precise experiment.