Lb. Knight et al., ELECTRON-SPIN-RESONANCE STUDIES OF THE TITANIUM CATION (TI-4) IN RARE-GAS MATRICES AT 4 K - A CRYSTAL-FIELD INTERPRETATION(,3D(3),F), The Journal of chemical physics, 105(13), 1996, pp. 5331-5340
Electron-spin resonance studies of laser-ablated titanium metal isolat
ed in neon and argon display an intense feature which exhibits a symme
tric, narrow line and a large matrix-dependent g shift. On the basis o
f a number of experiments, this is assigned to a matrix isolated 3d(3)
,F-4 Ti+ ion in an octahedral matrix environment. Although the ground
state of the gas-phase Ti+ ion is 3d(2)4s(1),F-4, the assignment to th
e 3d(3),F-4 State is supported by the small hyperfine structure which
is observed. The neon magnetic parameters are: g=1.934(1) and A (Ti-47
)=64(1) MHz; for argon, g=1.972(1) and A=56(1) MHz. This unusual stabi
lization of an excited atomic state by a rare gas matrix is consistent
with ab initio studies, and has been previously found for atomic nick
el. A crystal-field study of the expected behavior of a d(3),F-4 ion i
solated in a tetrahedral, octahedral, or cuboctahedral environment sup
ports the assignment to an octahedral Ti+(Rg)(6) species, and using th
e atomic spin-orbit parameter, zeta permits accurate values of Dq to b
e derived from the measured g values. Finally, it is also noted that f
or small values of Dq/(Dq+zeta), or for a d(3),F-4 ion in a tetrahedra
l environment, an as yet unobserved, unequal Zeeman splitting of the f
ourfold degeneracy occurs, causing a departure of the Zeeman energies
from the standard formula of E(Zeeman)=beta(e)H(0)gM, with M = +/-3/2,
+/-1/2. For these situations it becomes necessary to define two value
s of g, corresponding to the more strongly (g(3/2) and less strongly (
g(1/2)) affected Zeeman levels, respectively. (C) 1996 American Instit
ute of Physics.