Eur. Phys. J. D 44, 307-311 (2007)
https://doi.org/10.1140/epjd/e2007-00171-0

Absolute frequency and isotope shift measurements of the cooling transition in singly ionized indium

¹ Max-Planck Research Group, Institute of Optics, Information and Photonics, University Erlangen-Nuremberg, Günther-Scharowsky-Str. 1, Building 24, 91058 Erlangen, Germany
² School of Physical and Mathematical Sciences, Nanyang Technological University, 1 Nanyang Walk Block 5, Level 3, Singapore, 637616, Singapore
³ Max-Planck Institute of Quantum Optics, Hans-Kopfermann-Str.1, 85748 Garching, Germany

Corresponding authors: ^a zlu@optik.uni-erlangen.de - ^b lwan@optik.uni-erlangen.de

Received: 9 March 2007
Revised: 23 April 2007
Published online: 23 May 2007

Abstract

We report greater than two orders of magnitude improvements in the absolute frequency and isotope shift measurements of the In⁺ 5s^{2 1}S₀ (F = 9/2)–5s5p ³P₁ (F = 11/2) transition near 230.6 nm. The laser-induced fluorescence from a single In⁺ in a radio-frequency trap is detected. The fourth-harmonic of a semiconductor laser is used as the light source. The absolute frequency is measured with the help of a frequency comb referenced to a Cs atomic clock. The resulting transition frequencies for isotopes ¹¹⁵In⁺ and ¹¹³In⁺ are measured to be 1 299 648 954.54(10) MHz and 1 299 649 585.36(16) MHz, respectively. The deduced cooling transition frequency difference is 630.82(19) MHz. By taking into account of the hyperfine interaction, the isotope shift is calculated to be 695.76(1.68) MHz.