Near Infrared Cathodoluminescence of Xe 2 Excimers in Dense Gaseous Mixtures

Armando Francesco Borghesani^1*Giovanni Carugno²Federico Chiossi³

• ¹Department of Physics and Astronomy, School of Sciences, University of Padua, Padua, Veneto, Italy
• ²National Institute of Nuclear Physics of Padova, Padova, Italy
• ³ParisTech Chemistry - PSL University, Paris, Ile-de-France, France

We report new spectroscopic measurements of the near infrared (NIR) fluorescence band of electron-beam excited Xe 2 excimers as a function of the gas density in several gaseous mixtures of different Xe concentrations at room temperature. We have used He, Ar, and N 2 as buffer gases, the Xe concentration in the mixtures ranging from about 8 % up to 80 %. The investigated density range extends up to 10 times the density N ig of the ideal gas at standard temperature and pressure (N ig ≈ 2.5 × 10 25 m -3 ). In all mixtures we have observed that the wavelength of the centroid of the infrared excimer band is shifted towards longer wavelenghts as the gas density is increased, in a similar way as it was originally observed in pure Xe gas and in an Ar-Xe mixture.The strength of the redshift depends on the Xe concentration in the mixture and on the nature of the buffer gas and is very well rationalized by taking into account both the classical dielectric screening effect due to the gaseous environment and the density-dependent quantum shift of the energy of the optically active electron in the Xe 2 molecule, provided that the contribution of the two gaseous species in the mixture is weighted by applying the laws of ideal gaseous mixtures.