Abstract of Publication No. 398
The photophysical properties of Ti2+-doped NaCl and MgCl2
at 15 K are compared. At this temperature both materials emit luminescence
from their respective lowest excited states and from the 3T1g(t2geg)
higher excited state. In Ti2+:MgCl2 the ligand field
is significantly stronger than in Ti2+:NaCl, leading to 1T2g(t2g2)
and 3T2g(t2geg) lowest excited
states, respectively, in these materials. The near-infrared to visible
upconversion mechanisms of these two materials are identified. The
upconversion efficiency calculated for Ti2+:MgCl2 is
approximately 2 orders of magnitude higher than for Ti2+:NaCl.
This is mainly due to the more efficient energy storage in the
intermediate upconversion level in Ti2+:MgCl2, and
its higher 3T1g(t2geg) ->
quantum yield relative to Ti2+:NaCl.