Transcript CoS.ppt

Infrared emission spectroscopy of
the A 4Fi–X 4Di and B 4Pi–X 4Di
transitions of CoS
Shanshan Yu, Iouli E. Gordon,
Phillip M. Sheridan, and Peter F. Bernath
University of Waterloo, Canada
3d transition metal oxides and sulfides
 Their electronic spectra are generally very complex: unpaired
electrons can produce a huge number of low-lying electronic
states with high values of spin multiplicity and orbital angular
momentum, as well as large spin-orbital interactions, making
analysis of their spectra difficult.
 Theoretical calculations have difficulty getting the electron
correlation effects right, and it is hard to predict the energy
order and properties of their low-lying electronic states.
 Most 3d transition metal oxides have been well studied partly
due to their importance in astrophysics, while spectroscopic
studies on the sulfide counterparts are more limited.
Electronic states of CoO
Experimental work on CoS:
Flory et al. (2005): Microwave
Experimental work on CoO:
Green et al. (1979): Matrix
Adam et al. (1987): LIF
McLamarrah et al. (2005): Microwave
Ram et al. (1993): FTS
Barnes et al. (1997): LIF
Danset et al. (2003): Matrix
Barnes et al., J. Mol. Spectrosc. 186 (1997), 374
Experimental setup
Water jacket
To pump
Heating element
CS+
He
2
CS+
He
2
Sample
Insulation (carbon felt)
Carbon hearth
Temperature: ~3000 K
Resolution: 0.04 cm-1
Integration time: ~1 hour
Total scans: 100
the
4P
5/2
An overview of
4
X D7/2 transition of CoS
0-0
1-0
0-1
4600
4800
5000
5200
5400
-1
Wavenumber (cm )
5600
An expanded view of the 0-0 band of
4P
4D
X
5/2
7/2 transition of CoS
54.5
49.5
44.5
P(
5.5
9.5
19.5
14.5
39.5
R (+)
)
9.5
34.5
9.5
29.5
14.5
Q( )
*
+
+
* * *
* **
****
* * ****
*
+ + + + + +
+
5138
+
+
5140
5142
+
+
+
+ + + + + + + + ++ ++ ++++++
+
+
+
+
+
++
+++
+
+ +
5144
5146
-1
Wavenumber (cm )
An overview of
the 4Fi X 4Di transition of CoS
7 5

2 2
9 7

2 2
3200
3400
5 3

2 2
3600
3800
-1
Wavenumber (cm )
3 1

2 2
Data analysis
• We first performed Hund’s case (c) fits for
the observed subbands:
F(J) = Tv + BvJ(J+1) – Dv[J(J+1)]2
 ½[pv(J+1/2) + pDv(J+1/2)3 +
pHv(J+1/2)5 + pLv(J+1/2)7 ],
where pv, pDv, pHv and pLv are W-doubling
constants.
Case (c) constants (in cm-1)
for the X 4Di, A 4Fi and B 4 Pi states of CoS
State
Tv
X 4D7/2, v=0 0
X 4D7/2, v=1 514.52442(31)
A 4F9/2, v=0 3408.92171(51)
B 4P/2, v=0 5142.73509(43)
B 4P/2, v=1 5619.55633(45)
Bv
Dv/10-7
pv/10-3
pDv/10-9
0.207205911(46)
0.20613870(23)
0.19911315(11)
0.19851014(39)
0.19746112(71)
1.33499(15)
1.33990(79)
1.31204(16)
1.23015(69)
1.1925(23)
…
…
…
…
pHv/10-10
pLv/10-13
-0.476(28) 0.2141(52
-2.31(12) )1.478(41)
X 4D/2, v=0 0
0.207666543(38) 1.35157(14)
4
A F7/2, v=0 3665.04266(38) 0.199226841(86) 1.31807(14)
X 4D3/2, v=0 0
A 4F/2, v=0 3821.9039(14)
0.207934000(58) 1.35742(39)
0.1993561(26)
1.849(10)
X 4D1/2, v=0 0
0.208226134(36) 1.36260(13) 3.9384(26)
4
A F3/2, v=0 3920.56423(53) 0.19952068(32) 1.34683(42)
W-doubling splitting
J
2W
8.03(87)
…
…
Case (a) constants (in cm-1)
for the X 4Di and A 4Fi states of CoS
Constant
T0
A0
AD0/10-5
B0
D0/10-7
p0/10-9
o0/10-6
n0/10-4


a
 
D0/10-5

D/10-5
X 4Di
A 4Fi
0
-160.3a
-2.62378(29)
0.207759165(16)
1.351809(66)
3.94(57)
1.83(15)
6.5645(43)
22.3a
3.75701(38)
-0.71510(91)
…
3704.13298(32)
-163.141624(66)
1.3282(38)
0.19927642(27)
1.319618(68)
…
…
…
2.60388(15)
2.028(13)
-2.75155(63)
-2.286(18)
fixed at the values from the previous microwave study
The new low-lying A 4Fi state
 The presence of a low-lying 4Fi state for both CoS and CoO
was not anticipated based on previous experimental and
theoretical work.
 A 4F–4D transition is a fully allowed transition with DL=+1
and DS=0.
- Ram et al. did not observed this transition in CoO because
they used a filter.
- It is likely that in Danset et al.’s matrix study, the transition
at 3377 cm-1, which was assigned as the 4S-3/2–X 4D7/2
transition of CoO, was misasigned. We tentatively reassign
this transition to the A 4F9/2–X 4D7/2 transition of CoO.
 Attempts to generate CoO with our carbon tube king furnace
and to record this transition were made, but failed. The most
likely reason for this is that CoO was reduced to Co by carbon
at high temperature.
Conclusions
 The A 4Fi–X 4Di and B 4Pi–X 4Di transitions of CoS have been
observed in the near-infrared region for the first time.
Rotational analyses were carried out.
 The analogous 4P state for CoO has been observed previously
while the analogous 4F state in CoO remains to be located in
the gas phase.
 The presence of a low-lying 4F state for CoS and CoO was
not anticipated based on previous theoretical work. High
level ab initio calculations on CoO and CoS are desirable in
order to locate all of the low-lying states and determine their
configurations.
Infrared emission spectroscopy of
NiS
 Zheng et al. (2004): low-resolution laserinduced fluorescence spectroscopy.
An overview of the spectrum
NiS?
NiS?
3800
3900
4000
4100
4200
4300
4400
-1
Wavenumber (cm )
(NiO: A 3Pi–X 3S–, 4500 cm-1)
An expanded view of the spectrum
around 3940 cm-1
NiS?
3927
3930
3933
3936
Wavenumber (cm-1 )
3939
3942
Acknowledgements
Funding for this work was provided by the
Natural Sciences and Engineering Research
Council (NSERC) of Canada.