The Spark Spectrum of Nickel (Ni II)

The analysis of the spark spectrum of nickel shows that the important atomic structures are d⁸s and d⁸p. The low set of terms comprises ⁴F^', ²F^', ⁴P^', ²P^', ²D, ²G of which ⁴F^5' is lowest. The only expected term from the structure d⁸s which has not been found is ²S. All the intermediate terms (d⁸p) have been found with the exception of a ²P, and a doubtful ²F and ²S^'. A higher member of the ⁴F^'²F^' series (d⁸, s) has been found and indicates an I.P. of 17.4 volts from d⁸s to d⁸. The expected lowest term ²D(d⁹) has not been found. Terms are inverted with the following exceptions: (1) a⁴G^6' is higher than a⁴G^5', (2) a⁴P^3' is higher than a⁴P^1', (3) b⁴D^4' is higher than b⁴D^1', (4) triad b²P, D^', F is not inverted. Zeeman effects give some irregular g-values, but the g-sum rule is apparently satisfied. The g-sum rule is found to be not confined to terms built on the same ion term.