Chemistry Reference
In-Depth Information
10.2.2
r
eSultS
and
d
iScuSSion
10.2.2.1 Co
2
and Co
−
Existing. experimental. predictions. for. the. BE. of. the. Co
2
. dimer. are. contradictory:.
while.an.earlier.mass.spectroscopic.experiment.[71].estimated.a.BE.of.1.69.±.0.26.eV,.
a.more.recent.collision-induced.dissociation.experiment.[72].yielded.an.upper.bound.
of.1.32.eV,.and.inally.a.photodissociation.spectra.[73].yielded.a.value.in.the.range.of.
0.7-1.4.eV..The.mass.spectroscopy.study.[71].predicted.a.dimer.bond.length.of.2.31.Å.
calculated. from. Pauling. radius. and. a. total. magnetic. moment. of. 4.μ
B
.. Estimation.
via.Badger's.rule.gives.a.bond.length.of.2.02.Å.[74]..Hales.et.al..[72].measured.the.
ionization. potential. (IP). of. the. dimer. as. 6.42.eV,. which. was. previously. estimated.
as. 6.26.±.0.16.eV. [75].. The. vibrational. frequency. of. Co
2
. was. reported. by. different.
groups.as.290.cm
−1
.[76],.280.±.20.cm
−1
.[77],.and.296.8.±.5.4.cm
−1
.[78]..The.results.for.
the.properties.of.Co
2
.from.previous.theoretical.calculations.are.reported.in.Table.10.1.
along.with.experimental.estimations.
In.agreement.with.previous.irst.principles.calculations.[57-65],.we.ind.the.quin-
tet. spin. multiplicity. as. the. ground. state,. which. was. observed. in. experiments. [71]..
Triplet.and.septet.states.belong.to.the.irst.two.exited.states.that.lie.0.74.and.0.90.eV.
TABLE 10.1
Comparisons of the Present Results for Co
2
with Those of the Previous
Works Reported in the Literature
Binding
Energy (eV)
Bond
Length (Å
)
Vibrational
Frequency (cm
−1
)
Ionization
Potential (eV)
Reference
Experimental
[71]
1.69.±.0.26
2.31
[72]
≤.1.32
6.42
[73]
0.7-1.4
[75]
6.26.±.0.16
[76]
290
[77]
280.±.20
.
[78]
296.8.±.5.4
Theoretical
[66]
1.71
2.13
329
6.84
[57]
2.85
2.04
[58]
2.35
1.99
373
7.49
[59]
1.50
2.41
230
[60]
0.87
1.96
5.97
[61]
2.90
1.96
[62]
2.26
2.01
342
7.48
[63]
2.26
1.95
421
[64]
5.08
2.14
[65]
5.54
2.13
Source:
. Reprinted.from.
Chem. Phys
.,.354,.Sebetci,.A.,.Cobalt.clusters.(Co
n
,.
n
<=.6).and.their.anions,.
196-201,.Copyright.(2008)..With.permission.from.Elsevier.
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