MICROSCOPIC OBSERVATION OF THE S-]D TRANSITION IN METALLIC CESIUM UNDER HIGH-PRESSURE

Using the Cs-133 high-pressure Mossbauer effect technique, we were able for the first time to investigate on a microscopic level the pressure effects on the electronic charge densities and lattice dynamics in metallic cesium. A quantitative analysis of the experimental results reveals direct evidence for a gradual pressure-induced 6s --> 5d electronic transition in metallic cesium in agreement with band structure calculations. From the pressure-induced change of the Debye-Waller factor at 4.2 K, we obtain a new value of the Debye temperature theta(D) for metallic Cs of 64(2) K at p = 6 GPa (V/V0 = 0.33).