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Probing the electronic structure of the Nickel Monohalides: Spectroscopy of the low-lying electronic states of NiX (X=Cl , Br , I).
Lloyd MuzangwaMolecular Spectroscopy and Dynamics Group
M+
X-
66th International symposium on molecular spectroscopy
Our current understanding of nickel monohalides owes much to seminal studies of NiH by field and co-workers, the hydride served as a model for the spectroscopy of the heavier halides.
Leung and co-workers using laser vaporization/free jet expansion and LIF identified :
Ground state NiH and NiI identified to be 2D5/2
Ground state NiBr, NiCl and NiF identified to be 2P3/2
NiBr, the next highest state A2D5/2 from ground state is only 37.25 cm-1 above the X2P3/2.
The close proximity of the low-lying states in these species results in many perturbations.
What is known of Nickel monohalides ?
Cheung, et al , Journal of Chemical Physics, 119(23) (2003) .J.W.H. Leung, et al , Journal of Chemical Physics, 117 (2002) .
Why study SVL emission of nickel monohalides?
Gives complete vibrational data for the five low-lying electronic states associated with 3d9 configuration of Ni+
Reveals the presence of perturbation among the low-lying states
Complete analysis of NiCI, NiI and NiBr constants allow a detailed study of periodic trends within the nickel monohalide series.
Nd: YAGLaser
Dye laser
HV R2 R1
PC
PC
Spectrograph
PMT
Digital D
elay G
eneratorDigital Oscilloscope
Cath
ode
Lam
p
Proposed Mechanism
LASER
High pressure Ar
precursor: halogen containing:
VACUUM
DISCHARGE
DETECTORPMT/Spectrograph
CH3I, CD3I
CH2Br2 C2Cl4
SVL spectra of NiI via [21.6]2P3/2 v=2
* Discharge background
Comparison of SVL spectra recorded via different vibrational levels in the excited states show an intensity pattern reflecting the nodal structure of the vibrational wavefunction.
Source
T0
Term Energy
0 162.7 (1)
164
139
787.8 (2)
…………
812
1529.8 (1)
……………
1332
2140.2 (2)
……………
2210
This work
Ref. [30]
Ref. [35]
we
Vibrational
Frequency
278.5 (0.3)
276b
276.67b
290
273.2 (0.7)
271b
…………..
283
260.0 (5)
………….
…………..
274
277.5 (1)
…………
…………..
287
268.0 (2)
…………..
………….
281
This work
Ref. [48]
Ref. [30]
Ref. [35]
Xe
-0.74 (0.03) -0.85 (0.06) -0.45 (1.25) -0.89 (0.17) 0.02 (0.36) This work
Experimental constants (in cm-1 ) for NiI
X 2
5/ 2 A2
3/ 2 A2
1/ 2 X 2
3/ 2 B 2
1/ 2
One standard error given in parenthesis; b anharmonic values.
[30] W.S. Tam, et al, Journal of Chemical Physics, 119 (2003) [35] W.L. Zou, W.J. Liu, Journal of Chemical Physics, 124 (2006) .
[48] W.S. Tam, et al, Journal of Chemical Physics, 121 (2004)
X2P3/2 A2D5/2 X2P1/2 A2D3/2 B2S+1/2
Source
T0
0 43.3(1)
37b
165
488.9(1)
……………
583
1537.7(1)
…………….
1453
1843.1(1)
……………..
2214
This work
Ref [31]
Ref [35]
we
320.4(0.5)
331
336
326.9(1)
317
345
307.0(0.8)
…………
328
326.9(1)
……………
344
324.6(1)
…………..
335
This work
Ref [31]
Ref [35]
xe
-0.77(0.09) -0.81(0.18) -0.95(0.10) -0.93(0.13) -1.26(0.13) This work
Experimental vibrational constants for NiBr
One standard error given in parenthesis; b anharmonic values.
[31] E. Yamazaki, et al, Journal of Chemical Physics, 121 (2004) .
[35] W.L. Zou and W.J. Liu, Journal of Chemical Physics, 124 (2006).
X2P3/2 A2D5/2 X2P1/2 A2D3/2 B2S+1/2
Source
T0
0 166.9(1.7)a
268
158b
388.5 (0.2)
473
386
1654.3(2.5)
1549
1646
1776.5(10.2)
2002
1768
This work
Ref.[35]
Ref.[23, 24]
we
427.4 (1.7)
433
426
435.1 (1.6)
440
436
403.4 (0.9)
420
---------------
433.1 (2.1)
439
432
425.56 (7.9)
433
------------------
This work
Ref.[35]
Ref.[23, 24]
xe
-1.81 (0.49) -1.62 (0.26) -0.35(0.15) -1.94 (0.28) -1.70 (1.11) This work
Experimental vibrational constants NiCI
a One standard error given in parenthesis; b anharmonic values.[23] A. Poclet, et al , J Mol Spectroscopy, 204 (2000)
[24] Y. Krouti, et al , J Mol Spectroscopy, 210 (2001)
[35] W.L. Zou, and W.J. Liu, Journal of Chemical Physics, 124 (2006)
Periodic trends Vibrational constants in cm-1.
NiI
we
NiBr we NiCl
we NiF we
B2S+1/2
268 B2S+
1/2 324 B2S+1/2 425 A2D3/2 645
X2D 3/2 277 A2D3/2 326 A2D3/2 433 B2S+1/2 648
A2P 1/2 260 X2P1/2 307 X2P1/2 404 A2D5/2 646
A2P3/2 273 A2D5/2 326 A2D5/2 435 X2P1/2 607
X2D5/2 278
X2P3/2 320 X2P3/2 427 X2P3/2 637
Periodic trends in nickel monohalidesExperimental work
Theoretical work
SA-C
ASSC
F Ba
sis
set:
DKH
2
Laser induced fluorescence and single vibronic level emission spectroscopy has been used to probe five low-lying electronic states of NiI, NiBr and NiCI in the range 21 000- 24 000 cm-1.
The excited band structure was composed of isotope splitting.
Homogeneous (spin –orbit) perturbations have been identified and results from interactions between vibrational levels of the A2P3/2 and X2D3/2 states and A2P1/2 and B2S+
1/2 states.
In contrast to NiI , the spectra of NiBr and NiCl show few vibronic perturbations, reflecting the smaller spin-orbit coupling in these systems.
Overall, the computed spectroscopic constants and simulations were in good agreement with available theoretical data.
Conclusion
It would be interesting to compare trends for series with other transition metals.
Looking into polyatomic series example NiOH.
Forward Thinking
Acknowledgements
Isaac Newton,“ If l have been able to see further than
others, it is because l have stood on the shoulders of giants”
Thanks to Dr Scott Reid , My lab mates, and All for listening!!!!!!!!!!!!!!!!!!!!!!!