Transcript SiNSi_columbus1.ppt

LASER INDUCED FLUORESCENCE
SPECTROSCOPY OF THE SiNSi RADICAL II:
IDENTIFICATIONS OF THE A2A1, B2B1, AND
D2Sg+ STATES
C. MOTOYOSHI, Y. SUMIYOSHI, Y. ENDO
Department of Basic Science, The University of
Tokyo, Tokyo 153-8902, Japan
M. FUKUSHIMA, T. ISHIWATA
Faculty of Information Sciences, Hiroshima City
University, Hiroshima 731-3194, Japan
Background of the Study
Observation of LIF spectra of species containing
Si and N in the near UV region (30,000 – 34,000
cm–1)
Assigned the species to be linear SiNSi for the
2D – 2P system (previous talk)
u
g
However, there remained more vibronic bands,
which could not be assigend to the 2Du – 2Pg
system
Low-resolution LIF spectrum
vibronic bands for the 2Du–2Pg system
vibronic bands with shorter lifetimes (c. a. 50 ns)
Ab initio calculations
MRSDCI+Q / cc-pVTZ (9e in 9o)
7sg
3pu
2pg
X 2P g
5su
12Pu
C 2Du
D 2Sg+
High-resolution LIF spectrum
G. S. of the observed bands are that of SiNSi
P–P and S–P type vibronic bands were observed
Constants for the new bands
(cm-1)
Pu
Pu
Tv
30890.051(1)
31116.5016(9)
DE
0
226.45
Aveff
0
0
Bveff
0.11469(4)
0.11677(2)
104 qv
- 2.2(1)
- 4.85(4)
0.008
0.007
s
Tv
DE
Bveff
s
unresolved spin
components
⇒ vibronic P levels of
a S electronic state
S u+
S u+
S u+
31729.173(1)
31978.677(1)
32336.393(2)
839.12
1088.63
1446.34
0.11287(2)
0.11484(3)
0.11297(3)
0.009
0.007
0.021
(cm-1)
32400
The D2Sg+ state
Su +
(101)
predicted Te = 31300 cm-1
+n1(Sg)
32000
31800
Su +
(021)
Su +
(001)
vibronically allowed transitions
(only u vibronic levels are seen)
+n3(Su)
31200
31000
30800
Fu
Pu
Dg
Sg +
(030)
(020)
Pu
(010)
Sg +
(000)
Forbidden due to
centro-symmetry (g/u)
Rotational constants for the D2Sg+ state
Vibrational analysis for the D2Sg+ state

d

2
d
d

E
v
v
v

T

v


x
v
v


g
l
 


2
2


2 
2
2



3
3
j
l
i
i
1
2
3e
ii
i
ji
j
i
i

j


 d
 2
i
B

B

v

l
e
i
i
l

l
2


i
3
All vibronic energies are reproduced within 1 cm–1
Te
1
(cm-1) 29828(2) 608.0(5)
(cm-1)
Be
0.1132(2)
1
0 (fixed)
2
3
148(2)
959.6(7)
2
x22
- 5.8(3)
3
- 0.00099(4) 0.00085(9)
s
0.65
s
0.00008
The D 2Sg+ state has shallower bending potential curve
than that of the C 2Du state (2 = 233 cm-1).
Low-resolution DF spectra
C 2 Du → X 2 P g
D 2 Sg + → X 2 P g
High-resolution DF spectra
(030)Pu
pumped
(010)Pu
pumped
Observation of the A2A1 and B2B1 states
B2B1
D(021)
Fluorescence
D(010)
pump
12Pu
A2A1
D(030)
Linear
The energy at the linear
geometry (12Pu) is estimated
to be 13800 cm–1
B 2B1
A 2A1
Potential energies for the A2A1 and B2B1 states
MRSDCI+Q / cc-pVTZ (11e in 9o)
B2B1
B 2B1
A
2A
1
2B
2
X
2P
g
A2A1
2A
2
Ornellas and Iwata, J. Phys. Chem. 100, 10919 (1996)
low lying bent isomer
Low-resolution LIF spectrum in the visible
arrows indicate bands containing Si and N atoms
DF spectra from the visible bands
Analysis of the ground vibronic state
Observed levels when the 13363 cm-1 band was pumped (in cm-1)
Level
o.–c.
Assignment
Level
o.–c.
Assignment
0
(000)P1/2
838
- 0.2
(060)mP1/2
140
- 1.8
(000)P3/2
838
- 1.3
(060)mP3/2
268
–
?
874
–
?
285
- 3.4
(020)mP1/2
1039
2.9
(040)kP3/2
310
1.0
(020)mP3/2
1055
3.8
(040)kP1/2
534
1.3
(040)mP3/2
1118
1.8
(080)mP1/2
557
- 2.2
(040)mP1/2
1134
3.1
(040)kP3/2
605
- 2.8
(020)kP1/2
1389
- 3.5
(080)mP3/2
631
2.5
(020)kP3/2
1505
- 3.7
(060)kP1/2
0
Newly
obsered
Analyzed using the RT3 program (He and Clouthier, CPC 178, 676 (2008))
The determined parameters for the ground state
(cm-1)
2
e
187.8(3)
0.48(9)
ASO
155(2)
s
2.8
Conclusions
new band system, D2Sg+, has been assigned,
which becomes allowed by the vibronic coupling.
A
Dispersed
fluorescence spectra from the D state
showed new electronic states, which were assigned
to states with bent structures (A2A1 and B2B1 states).
Low-resolution
LIF spectrum for the visible system
was observed.
Dispersed fluorescences to higher vibronic levels for
the ground state have been observed by exciting this
system.