Selective excitation of odd gadolinium isotopes using two-colour photoionisation schemes

Selective excitation of odd isotopes of gadolinium has been carried out using two-colour photoionisation schemes. A new parameter ηsel-ion is defined for identifying optimum frequency positions for both excitation steps, where good isotopic selectivity can be achieved without significant sacrifice in the ion yield. The abundance of 155Gd and 157Gd isotopes were theoretically calculated and experimentally verified. All five photoionisation schemes are found to be useful for the selective ionisation of 155Gd and 157Gd isotopes.