Measurement of the 2S1/2-2D5/2 clock transition in a single 171Yb+ ion

Spectroscopy of the 411-nm transition in 171Yb+ has been performed and the feasibility of its use as an optical frequency standard has been demonstrated. The 2S1/2(F=0, mF=0)-2 D5/2(F=2, mF=0) frequency, at zero-magnetic field, has been measured to be 729 487 779 566(153) kHz. This transition is free from the first-order Zeeman shift and has a measured second-order shift of +0.38(8) Hz/(μT)2. In addition, the hyperfine structure of the 2D5/2 level has been deduced by driving the other hyperfine components of the 411-nm transition, showing it to be inverted. The 2D5/2 hyperfine splitting, measured to be -191(2) MHz, implies an A factor of -63.6(7) MHz. These data taken in conjunction with previous work yield an isotope shift of v171-v172=+1317.1(1.3) MHz for this transition between the 171 and 172 isotopes.