Determination of the isotope shift in the D 1 line between 197 Au and 195 Au

The isotope shift between197Au (stable) and195Au (T 1/2=183 d) was determined by resonance fluorescence and polarization spectroscopy in the 6s2 S 1/2 -6p 2 P 1/2, λ =267.6nm line. The result is δν195, 197=-2.9(2) GHz corresponding to a change of the mean-square charge radius by δ〈r 2〉195, 197=0.063(9) fm2. The sample was confined to a resonance cell heated to temperatures of up to 1500°C.