Knowledge Bank

The vacuum ultraviolet absorption spectra of Xe-rare gas and Kr-rare gas mixtures have been investigated between 1150 and 1500 {\AA}. These spectra are characterized by the appearance of band systems, often called ""satellite bands"", associated with allowed or forbidden Xe (Kr) atomic states. Quantitative absorption measurements with a double-beam Spectrophotometer as a function of pressure (p < 760 Torr) and temperature $(130\circ K$ T ) provide information on their bound or unbound diatomic molecular origin. From high resolution analysis of the spectra photographed with a ten-meter Spectrograph, information may be obtained on the excited states: the bands observed on the high energy side of the atomic transition are explained by molecular bound-free transitions. The bands observed on the low energy side arise from a minimum in the difference potential between the ground and the excited states.