LEVEL CLASSIFICATION IN THE CONFIGURATION 5D46S26P OF RE-I-185,RE-I-187 BY ISOTOPE SHIFT MEASUREMENTS

As a check on the classification we measured by optical hyperfine-structure (hfs) techniques the isotope shift (IS) of some levels of the odd Re I configuration 5d46s26p and obtained (related to the IS ≡ 0 of the ground state 6S 5 2) the values in brackets: z 6D 9 2 (-56(9) mK), z 6D 7 2 (-56(10) mK), z 6D 5 2 (-48(12) mK), z 6D 3 2 (-27(5) mK), z 6D 1 2 (+8(5) mK), z 6F 11 2 (-58(10) mK), z 6F 9 2 (-51(15) mK), y 6P 3 2 (+4(3) mK). Since an IS of ≈ +30(10) mK is to be expected, it must be concluded that - except for z 6D 1 2 and y 6P 3 2 -, the states in question have a dominant admixture of other odd parity configurations (5d56s6p and partly 5d66p). This con- clusion is fully supported by theoretical calculations communicated to us. The IS of the lines and hfs splitting constants of the levels concerned are also given. © 1979.