Laser ablation loading of a radiofrequency ion trap

The production of ions via laser ablation for the loading of radiofrequency (RF) ion traps is investigated using a nitrogen laser with a maximum pulse energy of 0.17 mJ and a peak intensity of about 250 MW/cm^2. A time-of-flight mass spectrometer is used to measure the ion yield and the distribution of the charge states. Singly charged ions of elements that are presently considered for the use in optical clocks or quantum logic applications could be produced from metallic samples at a rate of the order of magnitude 10^5 ions per pulse. A linear Paul trap was loaded with Th+ ions produced by laser ablation. An overall ion production and trapping efficiency of 10^-7 to 10^-6 was attained. For ions injected individually, a dependence of the capture probability on the phase of the RF field has been predicted. In the experiment this was not observed, presumably because of collective effects within the ablation plume.Comment: submitted to Appl. Phys. B., special issue on ion trappin

COOLING AND TRAPPING OF LASER INDUCED MULTIPLY CHARGED IONS OF MOLYBDENUM

Low-energy multiply charged ions of molybdenum have been produced and stored using a novel technique which combines laser ablation and ion storage. The charge states range from q=+1 to q=+6. The energy of these ions is estimated to be less than 5x10-3eV/amu with the storage time of one second. The number of stored ions is about 105. These findings suggest that we can now study the slow processes of low energy multiply charged ions of most elements