A Compact and Versatile UHV Chamber for High Resolution Spectroscopy using Laser Excited Atomic Fluorescence Spectroscopy (LEAFS)

Aresistively heated graphite tube atomic beam apparatus and a compact laser-atom interaction chamber for sub-Doppler fluorescence experiments have been developed. We have studied the evolution of the system from Doppler broadened conditions to Doppler limited conditions which enabled us to study the sub-Doppler hyperfine spectroscopy of rubidium and potassium. The compact interaction geometry, flexibility in changing the atomic beam source and simplicity of the entire set up make it usefid for the measurement of isotope shifts and hyperfine structure measurement of single/multistep excitations of various elements. Test experiments were conducted with the atomizer by loading rubidium and potassium in order to find the optimum design conditions for the set-up. The sub-Doppler hyperfine structure peaks of the ³⁵Rb and ⁸⁷Rb isotopes have been measured and the full width at half maximum of the recorded peaks are- 16MHz for the 5²S_1/2-5²P_3/2 D2 transition of rubidium which is close to the natural broadening of this transition. The total number of rubidium atoms leaving the source aperture is estimated to be 2.7 ×10¹⁴ atoms/sec. The number of rubidium atoms in the region of interaction is 2.4 × 10⁹ atoms/cm² in a laser beam of 0.3cm diameter. The sub-Doppler hyperfine structure of the ³⁹K and ⁴¹K isotopes has also been recorded for the 4²S_1/2-5²S_1/2 D1 transition of potassium. The overall detection efficiency of the LEAFS process is found to be ~2×10^-11.