High spin states in lead isotopes with 193<=A<=199

Theγ de-excitation of odd neutron deficient lead isotopes with mass numbers 193–199, produced by (heavy ion,x n) reactions, was studied with the particular aim of searching for high spin states of the (i13/2)^?3 configuration. The properties of levels in^{199, 197, 195}Pb are compared with the predictions of a three quasi-particle calculation, forJ=29/2?15/2, and with the corresponding results in the neighbouring even lead isotopes.     

Analogies and differences between calcium-based and europium-based graphite intercalation compounds

An original method using lithium-based liquid alloys has been developed, allowing studies on bulk graphite intercalation compounds with calcium and europium. We showed that binary and ternary compounds belonging to graphite-lithium-calcium and graphite-lithium-europium systems are synthesized in both cases for equivalent reaction conditions but amazingly with many different structural and physical properties. Concerning CaC₆ and EuC₆, even if their 2D unit cells are hexal, their c-axis stacking sequences lead to different symmetries. Regarding kinetical data, formation mechanisms of these graphite intercalation compounds appear comparable however different, with a first common step before differenciation in the intercalation mechanism. Obviously, their physical properties are strongly different due to the nature of the intercalated metallic element. So, the different ternary compounds from these systems also show very considerable differences concerning their electronic properties: complex magnetic ordering for Eu-based ternary GIC and superconducting behaviour for Ca-based ternary GIC. However, common points are highlighted.