Bose-Einstein condensation, an effect long known for material particles as cold atomic gases, has in recent years also been observed for photons in microscopic optical cavities. Here, we report absorption and emission spectroscopic measurements on the lowest electronic transition ($5p^6\to 5p^{5}6s$) of xenon, motivated by the search for a thermalization medium for photon Bose-Einstein condensation in the vacuum-ultraviolet spectral regime. We have recorded pressure-broadened xenon spectra in the 135- to 190-nm wavelength regime at conditions near the critical point. The explored pressure and temperature ranges include high-pressure gaseous xenon below the critical pressure and supercritical xenon at room temperature as well as liquid xenon close to the boiling point near the critical pressure.

中文翻译：

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气态，液态和超临界氙的真空紫外吸收和发射光谱

近年来，对于微观光学腔中的光子，人们还观察到了玻色-爱因斯坦凝聚现象，这种现象长期以来对于材料粒子如冷原子气体而为人所知。在这里，我们报告了在最低电子跃迁下的吸收和发射光谱测量（$5p^6\to 5p^{5}6s$），其动机是寻找真空紫外光谱中光子玻色-爱因斯坦凝聚的热化媒介。我们已经在临界点附近的条件下在135 nm至190 nm波长范围内记录了压力扩大的氙光谱。探索的压力和温度范围包括低于临界压力的高压气态氙和室温下的超临界氙以及接近临界压力且接近沸点的液态氙。