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Abstract

Cold, precisely localized highly charged ions are of particular interest for metrology and investigations of fundamental physics, such as possible drifts in the value of the fine structure constant alpha. Recently, it was possible to prepare Coulomb crystallized ultra-cold ⁴⁰Ar¹³⁺-ions through sympathetic motional cooling in a cryogenic linear Paul trap [1]. For the spectroscopic investigation of the ²P_3/2 - ²P_1/2 M1 transition at 441nm in boronlike ⁴⁰Ar¹³⁺ions sympathetically cooled to the mk-range, a tuneable Ti:Sa laser at 882nm with 100 kHz linewidth was built at the PTB. The laser setup including the frequency stabilization to a transfer cavity, which is locked to a Rubidium hyperfine transition using the Transfer-Modulation-Spectroscopy technique is presented. A first measurement of the MTS error signal is shown. For the sympathetic cooling of HCIs, ⁹Be⁺ is the coolant ion of choice. The cooling laser drives the ²S_1/2 - ²P_3/2 transition at 313 nm. For both precision spectroscopy of ⁴⁰Ar¹³⁺and time dependent fluorescence measurements of ⁹Be⁺, power stabilization of the cooling laser is a necessary prerequisite. Therefor two intensity stabilization schemes were implemented and tested. Furthermore a setup for the determination of the Paul trap heating rate was built, which was tested by measuring the Doppler recooling times of a 0,5mm sized ⁹Be⁺ Coulombcrystal.