Precision frequency measurement of the clock transition in a Sr/sup +/ single atom with an ultra-stable diode laser

We are studying a single Sr/sup +/ atom confined in a Paul trap to produce a frequency standard in the visible region of the spectrum. The goal is to excite a clock transition of the ion at 674 nm with a diode laser and measure its absolute frequency. It is only possible to probe the 0.3-Hz transition if the diode laser is extremely stable during the measurement process which in this experiment can take several minutes to complete. Frequency stabilization of the probing laser was achieved with a lock to an ultra-stable Fabry-Perot cavity. The cavity was temperature stabilized and has demonstrated good long term stability.