62nd osu international symposium on molecular spectroscopy ta12 laser spectroscopy of iridium...
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62nd OSU International Symposium on Molecular Spectroscopy TA12
Laser Spectroscopy of Iridium Monoboride
Jianjun Ye, H. F. Pang, A. M-Y. Wong, J. W-H. Leung,
and A. S-C. Cheung
Department of Chemistry, The University of Hong Kong,
Pokfulam Road, Hong Kong, P. R. China
1
Introduction
Some metal-containing boride molecules:
*The spectroscopic studies of diatomic metal-containing borides
are limited to the theoretical investigation.
*Experimental investigation of this series of molecules remains
almost unexplored. Only very few broide molecules:
PdB, studied by electron spin resonance (ESR) spectroscopy.
RhB, studied by laser induced fluorescence (LIF) spectroscopy.2
Present work
High resolution LIF spectrum of IrB between 545 to 610 nm
has been recorded and analyzed:
*(v, 0) with v = 0 – 3 of all four isotopic molecules: 191Ir10B, 193Ir10B, 191Ir11B and 193Ir11B were recorded.
*Partially resolved hyperfine structure conformed to case a
coupling scheme has been observed.
3
Experimental DetailsThe experimental setup of laser ablation/reaction and LIF
4
Molecule Production: Ir (Vapor) + B2H6 → IrB + etc.
Vaporization Laser: Nd:YAG, 10Hz, 532nm, 5mJ
Free Jet Expansion:
i) backing pressure: 5 atm (Ar + 1% B2H6)
ii) background pressure: 1x10-5Torr
Spectral line width: about 250MHz
5
Results and Analysis
Low-resolution LIF spectrum of ' = 2 – " = 3 band system of IrB
6
16500 17000 17500 18000 18500
191Ir10B
191Ir10B
193Ir11B
191Ir11B
(3,0)(2,0)(1,0)(0,0)
(3,0)(2,0)(1,0)
(0,0)
Wavenumber (cm-1)
The (0,0) band of the ' = 2 – " = 3 transition of IrB
7Wavenumber (cm-1)
16525 16530 16535 16540 16545 16550
P(J)
Q(J) R(J)
P(J)
Q(J)3
3
7 3
10 5 3753 193Ir10B
191Ir10B
193Ir11B10 5
14 10 575
3
191Ir11BR(J)
The (2,0) band of the ' = 2 – " = 3 transition of IrB
8
Wavenumber (cm-1)
17780 17785 17790 17795 17800
P(J)
P(J)Q(J)
Q(J)
R(J)
R(J)
3
3
3
3
3
191Ir11B
193Ir11B
7 5
10 5
85
7 5
10 5
105
Molecular constants for the ' = 2 and " = 3 states of IrB (cm-1)
9
Parameter 191Ir11B 193Ir11B 191Ir10B 193Ir10B
' = 2
T3 18350.286(2) 18349.943(2)
B 0.47235(3) 0.47204(3)
T2 17791.129(2) 17790.787(2)
B 0.47455(2) 0.47424(3)
T1 17186.970(2) 17186.679(2)
B 0.47321(2) 0.47294(2)
T0 16541.845(1) 16541.845(1) 16535.824(2) 16535.824(2)
B 0.47336(4) 0.47336(4) 0.51860(2) 0.51860(2)
" = 3
T0 0.000 0.000 0.000 0.000
B 0.51809(4) 0.51809(4) 0.56684 0.56684
Reduced term value plot of v = 2 level of = 2 and = 3 states of IrB
10
0 20 40 60 80 100 120 140 160
17784
17786
17788
17790
17792
17794
Tv-0
.45J(J
+1)
J(J+1)
Electronic configuration IrN 12 14 22 14
IrC 12 14 22 13
IrB 12 14 22 12 ?
2 1+ , 3¯ and 1
There is no = 3 substate from 2
Ir B
2p6s5d
3
2
1
1
2
1
Possible electronic configuration for the ground state of IrB
(1) 12 14 22 11 21 1, 3, 1, 3 (2) 12 14 22 22 1 , 3
Tentative assignmentGround state X 13 Excited state [ 16.5 ] 1 2
12
The (1,0) band of the ' = 2 – " = 3 transition of IrB with partially resolved hyperfine structure
Wavenumber (cm-1)
17185.0 17185.5 17186.0 17186.5
0.0401cm-1
0.0373cm-10.0506cm-1
0.0465cm-1
0.0620cm-1
Q'(5)
Q'(4)
Q'(3)
Q(5)
Q(4)
Q(3)
Q - 191Ir11BQ' - 193Ir11B
0.0584cm-1
Analysis of hyperfine structureHyperfine structure in the
[16.5] 12 - X 13 transition
Judging from the size of the atomic magnetic moment for both
Atom I (mag. dip.)193Ir 3/2 0.16
B 3/2 2.688
We ascribe the large hyperfine interaction to the B atom
zzzzhfs SIcSIbLIaΗ ˆˆˆˆˆˆˆ
In case a coupling scheme
)1(2
)]1()1()1([
JJ
JJIIFFhIFJΗIFJ hfs
)( cbah
For a 13 state ( = 3 and = 0)
h" = 3aFor a 12 state ( = 2 and = 0)
h' = 2a
Hyperfine structure
Q(3) line
Case a F = I + J
7/2
F
J = 3
12
J = 3
X13
9/2
5/23/2
9/2
7/2
5/2
3/2
q(F”)
15
The (1,0) band of the ' = 2 – " = 3 transition of IrB with partially resolved hyperfine structure
Wavenumber (cm-1)
17185.0 17185.5 17186.0 17186.5
0.0401cm-1
0.0373cm-10.0506cm-1
0.0465cm-1
0.0620cm-1
Q'(5)
Q'(4)
Q'(3)
Q(5)
Q(4)
Q(3)
Q - 191Ir11BQ' - 193Ir11B
0.0584cm-1
Using linewidth measured from the Q and P branches.
The hyperfine constants are estimated to be
X13 state h = 0.0286 cm-1
[16.5] 12 state h = 0.0116 cm-1
ah
3
"" hha
1cm00950 " - .a for X 13 state 1cm005800 ' - .a for [16.5] 12 state
iiNBN rgg
hca 3
4
1cm 00531.0
9293.02/3
6885.2 00318625.0
Summary
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*Preliminary analysis of the rotational lines showed that
these vibronic bands are with ' = 2 and " = 3.
*Partially resolved hyperfine structure conformed to case
a coupling scheme has been observed.
Acknowledgments
19
This work was supported by grants from the
Research Grants Council of the Hong Kong SAR,
China (Project No. HKU 7015/04P) and Committee
on Research and Conference Grants, The University
of Hong Kong.