Selective resonance ionization of calcium odd isotopes with odd–even selection rules

Odd-even isotope selectivity in calcium was investigated using a laser resonance ionization $$J=0-1-0$$ transition scheme, chosen so that angular momentum selection rules could be applied using linearly polarized light. Suppression of the abundant isotope $$^{40}\hbox {Ca}$$ and selection of the rare isotope $$^{43}\hbox {Ca}$$ was confirmed as a function of the linear polarization angle, through simple application of a half-waveplate ( $$\lambda /2$$ ). In the electric dipole basis, by the selection rules, setting transition polarizations linearly orthogonal forbids the excitation of the even isotopes, while allowing the odd isotope excitation. Spectroscopy in the Rydberg level transition also showed selectivity in the resonance ionization process, with a final maximal (dependent on hyperfine transition) selectivity reported as a separation coefficient $$\beta = {9e3} $$ . It is expected that this relatively simple method in increasing selectivity of resonance ionization will have application to separation of the rare odd Ca isotopes as they are important in areas such as quantum information via ion trapping ( $$^{43}\hbox {Ca}$$ ), and cosmology and biomedicine ( $$^{41}\hbox {Ca}$$ ).