Chemistry Reference
In-Depth Information
Fig. 2.17 A single crystal of
[Fe(ptz)
6
](BF
4
)
2
(size ca.
3 9 3cm
2
) is colorless at
room temperature. The
absorption spectrum shows
only a weak absorption band
at ca. 12,000 cm
-1
.At80K
the crystal has changed
totally to the LS state by
thermal SCO and is now red
and absorbs relatively
strongly at 18,000 and
26,000 cm
-1
. Irradiating the
crystal at ca. 10 K converts
the LS state to the metastable
HS state. The optical
spectrum of the white spot
(ca. 1 mm in diameter) is
practically identical to the
one recorded at 300 K
57
Fe Mössbauer
Fig. 2.18
Light induced spin state switching in [Fe(ptz)
6
](BF
4
)
2
followed by
spectroscopy [
26
]
quadrupole doublet is due to the plate-like shape of the crystals (texture effect).
Thermal relaxation on a 15 min-timescale sets in at 50 K (lower left and upper
right: the sample was heated for 15 min at 50 K and then cooled to the measuring
temperature of 15 K in two runs). Thermal relaxation to the stable LS state is
