Strong probe atom dependence of the electric field gradient in Bismuth

The nuclear quadrupole interaction of the 8⁺ isomers in^{206, 208}Po was measured in the semimetallic host Bi. The comparison of the extracted electric field gradient eq for PoBi with the values for the neighboring elements Bi and Pb as probe atoms in Bi reveals a very drastic increase from Pb to Bi and to Po by an order of magnitude: eq_PbBi eq_BiBi eq_PoBi =1.64(10)4.8(3)16(2)(all values at room temperature in units of 10¹⁷ V/cm²). This behavior is discussed in terms of the changing number of outerp-electrons of the probe atoms.