Laser Spectroscopic Investigation of the Element Fermium (Z = 100)

The level scheme and hyperfine structure of the element fermium (Z = 100) has been investigated with the method of resonance ionization spectroscopy in a buffer gas cell. The experiments were carried out on a 46 pg sample of the isotope 255Fm with a half-life time of 20.1 h, produced in the high flux nuclear reactor of the ORNL, Oak Ridge, USA. A wave number scan from 27,100 to 28,400 cm−1 was carried through to search for three levels with large Einstein-coefficients, as predicted by ab initio Multi-Configuration-Dirac-Fock (MCDF) calculations, and five new levels were found. In addition, the two known levels at wave numbers (25,099.8 ± 0.2) and (25,111.8 ± 0.2) cm−1 were studied with a laser band width of 1.5 GHz and hyperfine broadenings were observed.