Synchrotron X-ray Absorption Spectroscopy - Stanford Synchrotron ...

Transition
Dipole
Quadrupole
Transition
Dipole
Quadrupole
Selection Rules for X-ray absorption
near-edge spectra
Selection rule
∆l=±1
∆l=±2
K, L I , M I
ns →n´p
ns →n´d
Strength
Intense
Weak
K-edge
np →n´d
np →n´f
1s →np
1s →nd
L II , L III , M II , M III
LIII-edge 2p →nd
2p →nf
M IV , M V
nd →n´f
nd →n´g
I. J. Pickering and G. N. George GEOL 498.3/898.3
Tungsten L-edges – Selection Rules
XAS L-edge spectra of Na 2 WO 4 –W(VI) is 5d 0 , so we expect strong dipole
allowed transitions to the 5d manifold at the L III and L II edges from the
2p 3/2 and 2p 1/2 , respectively. No such intense transitions are expected at
the L I near-edge (2s excitation).
W L III W L II
W L I
I. J. Pickering and G. N. George GEOL 498.3/898.3
Uranium M-edges – Selection Rules
XAS M-edge spectra of UO 2 (CH 3 CO 2 ) 2 (H 2 O) 2 –U(VI) is 5f 0 , so we expect
strong dipole-allowed transitions to the 5f manifold at the M V and M IV edges
from the 3d 3/2 and 3d 1/2 , respectively. No such intense transitions are
expected at the M III , M II (3p 3/2 and 3p 1/2 excitation, respectively) or M I (3s
excitation) near-edges.
M V
M IV MIII
O O OH2 O U
O
H2O O
O
I. J. Pickering and G. N. George GEOL 498.3/898.3
M II
M I