Spectroscopy of a narrow-line optical pumping transition in atomic dysprosium

We present measurements of the hyperfine coefficients and isotope shifts of the Dy I 683.731 nm transition, using saturated absorption spectroscopy on an atomic beam. A King Plot is drawn resulting in an updated value for the specific mass shift δν164−162684;sms −534 17 MHz. Using fluorescence spectroscopy, we measure the excited state lifetime τ684 1.685 μs, yielding a linewidth of γ684 95 3 kHz. We give an upper limit to the branching ratio between the two decay channels from the excited state showing that this transition is usable for optical pumping into a dark state and demagnetization cooling. © 2013 Optical Society of America OCIS codes: 300.0300, 300.2530, 300.3700, 300.6460, 020.2930, 020.3260. In atomic physics, rare-earth elements provide several applications: for instance dysprosium has been used to search for a possible variation of the fine-structure con-stant [1]. Transverse laser cooling of a beam of dyspro-sium atoms has been demonstrated [2] and recently quantum degenerate gases of bosonic and fermionic dys-prosium [3,4] and bosonic erbium [5] have been achieved, both with very large magnetic dipole moments μD