Ultraviolet spectroscopy and thermodynamics of ultradense gas mixtures

在高密度原子和分子介质，如染料溶液和碱性缓冲气体混合物的高压下的吸收和发射线之间，在许多情况下存在普遍的热力学标度，即Kennard-Stepanov关系，这是详细平衡的表现。在前期工作中，这使得我们的团队能够证明光子的第一个玻色-爱因斯坦凝聚，以及第一个由碰撞诱导的激光冷却气体的演示。这项研究项目的直接目标是演示一种测定绝对温度的新的光谱方法。在计划的调查框架内，在对致密系综的初步工作中进行的吸收和发射的光谱测量，其中碰撞展宽达到以频率为单位的热能，将扩大到在室温下已经是气态的样品。我们打算研究稀有气体氙气和小分子的混合气体，例如，在100-200bar压力下，以Ar作为缓冲气体，这将通过在紫外线和真空紫外光谱区的测量而成为可能。通过记录高气体密度下的吸收和发射光谱，可以验证原子和分子混合气体的热力学Kennard-Stepanov关系，这应该允许对温度进行光学频率测量。这项工作的未来前景是在真空-紫外线光谱区域实现玻色-爱因斯坦凝聚体，作为该波长范围内的相干光源，这对于通常的激光来说是很难获得的，例如用于光刻或医疗应用。这项工作也将形成碰撞诱导激光冷却从室温开始的“宏观”稠密气体系综的实验基础。

Between the absorption and emission lines of dense atomic and molecular media, such as dye solutions and alkali buffer gas mixtures at high pressure, in many cases there exists a universal thermodynamic scaling, the Kennard-Stepanov relation, a manifestation of detailed balance. In preliminary work, this enabled our group to demonstrate the first Bose-Einstein condensation of photons, as well as the first demonstration of collisionally-induced laser cooling of gases. The immediate goal of this research project is the demonstration of a new spectroscopic method for the determination of the absolute temperature. In the framework of the planned investigations, spectroscopic measurements of absorption and emission performed in preliminary work on dense ensembles, where the collisional broadening reaches the thermal energy in frequency units, will be extended to samples which are already gaseous at room temperature. We intend to investigate gas mixtures of the noble gas xenon, as well as small molecules, with, for example, argon as a buffer gas at 100-200 bar pressure, which will be made possible by measurements in the ultraviolet and vacuum ultraviolet spectral regions. By recording absorption and emission spectra at high gas densities, the thermodynamic Kennard-Stepanov relation for atomic and molecular gas mixtures can be verified, which should allow an optical frequency measurement of the temperature. A future perspective of the work is the realization of Bose-Einstein condensates in the vacuum-ultraviolet spectral regime, as coherent sources of light in this wavelength range, which is difficult to access for usual lasers, for example for lithography or medical applications. The work will also form the basis for experiments on collisionally-induced laser cooling of "macroscopic" ensembles of dense gases starting from room temperature.