We begin therefore by showing in the left-hand
columns of Table I the configurations given by
Martin et al. for lanthanum through lutetium.
Here it is seen that at the fourth spectrum the 4f
level has in all cases fallen below 5d and 6s. This
is due to the well-known phenomenon of 4f wavefunction
collapse [reference 5]. The effective potential in
which the 4f electron moves is made up of an attractive
Coulomb term and a repulsive centrifugal
term, which, in general, combine to give a double
well potential, the height of the intervening barrier
depending on the nuclear charge Z. For neutral
atoms the field in the region of the outer potential
is essentially hydrogenic. The occurrence of the
neutral lanthanides coincides with the appearance
of bound 4f levels in the inner well, which, in turn,
is due to the deepening of the well and the lowering
of the potential barrier as a result of the increasing nuclear charge.
We begin therefore by showing in the left-hand columns of Table I the configurations given by Martin et al. for lanthanum through lutetium. Here it is seen that at the fourth spectrum the 4f level has in all cases fallen below 5d and 6s. This is due to the well-known phenomenon of 4f wavefunction collapse [reference 5]. The effective potential in which the 4f electron moves is made up of an attractive Coulomb term and a repulsive centrifugal term, which, in general, combine to give a double well potential, the height of the intervening barrier depending on the nuclear charge Z. For neutral atoms the field in the region of the outer potential is essentially hydrogenic. The occurrence of the neutral lanthanides coincides with the appearance of bound 4f levels in the inner well, which, in turn, is due to the deepening of the well and the lowering of the potential barrier as a result of the increasing nuclear charge.
According to Ground-state configurations of ionic species I through XVI for Z = 57-74 and the interpretation of 4d-4f emission resonances in laser-produced plasmas Phys. Rev. A 25, 275 (where "I" means the neutral atom) :
Here, "reference 5" is Spectral Distribution of Atomic Oscillator Strengths Rev. Mod. Phys. 40, 441 which goes into quantitative equations for the attractive Coulomb term and a repulsive centrifugal term.
According to Ground-state configurations of ionic species I through XVI for Z = 57-74 and the interpretation of 4d-4f emission resonances in laser-produced plasmas Phys. Rev. A 25, 275 (where "I" means the neutral atom) :
Here, "reference 5" is Spectral Distribution of Atomic Oscillator Strengths Rev. Mod. Phys. 40, 441 which goes into quantitative equations for the attractive Coulomb term and a repulsive centrifugal term.
More
VOTE
VOTE
VOTE
VOTE
VOTE