High-resolution isotope-shift spectroscopy of Cd I

Abstract

We present absolute frequency measurements of the 1P1←1S0 (229-nm) and 3P1←1S0 (326-nm) transitions for all naturally occurring isotopes of cadmium. The isotope shifts and hyperfine intervals of the fermionic isotopes are determined with an accuracy of 3.3 MHz. We find that quantum interference in the laser-induced fluorescence spectra of the 1P1←1S0 transition causes a variation of up to 29(5) MHz in determining the hyperfine splitting when not accounted for with an appropriate model. Using a King-plot analysis, we extract the field- and mass-shift parameters and determine nuclear charge radius differences for the fermions. The lifetime of the 1P1 state is determined to be 1.60(5) ns by measuring the natural linewidth of the 1P1←1S0 transition. These results resolve significant discrepancies among previous measurements.