SPECTROSCOPY OF A SINGLE TRAPPED INDIUM ION

We report on laser spectroscopy of an In+ ion stored in a radio-freque ncy trap. The aim is to develop an optical frequency standard based on the (5sS0)-S-21 --> (5s5pP0)-P-3 transition at 236.5 nm, which has a natural linewidth of only 1.1 Hz. A diode-pumped Nd:YAG laser operatin g on the 946-nm line was developed. The fourth harmonic of this radiat ion will be used to excite the clock transition of the indium ion. The ion is stored in a miniaturized Paul-Straubel trap that provides a la rge solid angle for the optical observation and a steep potential for good localization of the ion. For laser cooling, the intercombination line (5sS0)-S-21 --> (5s5pP1)-P-3 at 230.6 nm is excited. We present e xperiments on laser cooling of a single ion and the observation of ele ctron shelving in the Metastable P-3(0) state.