Transcript ZnS.ppt

64th International Symposium on Molecular Spectroscopy
June 26, 2009
The Pure Rotational Spectrum of
ZnS (X1+)
Lindsay N. Zack
Lucy M. Ziurys
Department of Chemistry, Department of Astronomy, Steward
Observatory, and Arizona Radio Observatory
University of Arizona
64th International Symposium on Molecular Spectroscopy
June 26, 2009
Previous Work
• Mass spectrometry
– Dissociation energy (Marquart and Berkowitz 1963; de Maria et al. 1965)
• Spectroscopic measurements
– Absorption spectroscopy of ZnS in l7000-1900 region (Sen-Gupta
1933)
– X-ray emission and luminescence spectroscopy of crystals and
nanoparticles (Laihia et al. 1996; Denzler et al. 1998)
• Theoretical calculations
– Different levels of theory with and without relativistic
corrections (e.g. Bauschlicher and Langhoff 1986; Peterson et al. 2007)
– Similarities between single molecule and bulk properties (Anderson
et al. 1987; Bridgeman and Rothery 2000; Chambaud et al. 2008)
– re ~ 2.04 – 2.12 Å
64th International Symposium on Molecular Spectroscopy
Instrumentation
•
•
•
•
•
•
Direct-absorption spectroscopy
Phase-locked Gunn oscillators
and Schottky diode multipliers
(65-850 GHz)
Gaussian beam optics
Reaction chamber: double-pass,
water-cooled steel cell containing
a Broida-type oven
InSb bolometer detector
Radiation is modulated at 25 kHz
and detected at 2f
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64th International Symposium on Molecular Spectroscopy
Direct-absorption
mm/sub-mm wave
spectrometer
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64th International Symposium on Molecular Spectroscopy
Molecular Synthesis
• Gas-phase synthesis
• Zinc vapor produced in Broida-type oven
– Alumina crucible in tungsten wire basket
– m.p. 420 C
• H2S added over top of oven
• Argon carrier gas
• d.c. discharge needed (250 mA at 200 V)
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64th International Symposium on Molecular Spectroscopy
380000
390000
400000
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410000
Frequency (MHz)
42 GHz (~7B) initially scanned continuosly
64th International Symposium on Molecular Spectroscopy
June 26, 2009
64Zn
: 66Zn : 67ZnS: 68Zn : 70Zn
49: 28:
4: 19: 0.6%
68ZnS
66ZnS
v=0
v=0
64ZnS
v=0
64ZnS
66ZnS
v=1
67ZnS
v=1 v=0
376000
378000
380000
Frequency (MHz)
382000
384000
64th International Symposium on Molecular Spectroscopy
64
ZnS (X1+): J = 37
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36
v=0
v=1
414581
414606
417000
Frequency (MHz)
417025
64th International Symposium on Molecular Spectroscopy
June 26, 2009
Transition Frequencies
64ZnS
66ZnS
nobs-calc
n
67ZnS
nobs-calc
n
68ZnS
J’
J”
v
n
nobs-calc
n
nobs-calc
33
32
0
372 072.494
-0.028
34
33
0
383 312.402
0.010
379 453.171
-0.032
377 605.094
-0.013
375 817.323
-0.020
35
34
0
394 549.133
0.011
390 577.179
0.007
388 675.054
-0.016
386 835.077
0.003
36
35
0
405 782.628
0.008
401 698.004
0.029
399 741.917
0.021
397 849.714
0.016
37
36
0
417 012.800
0.006
412 815.526
0.006
410 805.501
0.005
408 861.131
0.003
38
37
0
428 239.552
<0.000
423 929.716
-0.001
421 865.783
0.002
419 869.277
0.002
40
39
0
450 682.455
0.005
446 147.698
-0.008
443 976.060
0.016
441 875.363
0.002
41
40
0
461 898.392
-0.130
457 251.325
0.008
455 025.849
0.005
452 873.127
0.003
42
41
0
468 351.209
-0.009
466 071.949
-0.020
463 867.240
-0.009
34
33
1
381 096.161
-0.015
377 270.558
0.016
35
34
1
392 267.552
0.022
388 330.111
-0.020
36
35
1
403 435.640
0.005
37
36
1
414 600.387
-0.013
410 439.672
0.001
38
37
1
425 761.723
-0.007
421 489.437
-0.002
40
39
1
448 073.724
0.007
443 578.528
0.011
41
40
1
459 224.195
0.007
454 617.644
-0.002
42
41
1
470 370.846
-0.008
465 653.042
-0.003
64th International Symposium on Molecular Spectroscopy
June 26, 2009
Constants
Rotational and equilibrium constants for ZnS (1+)a.
64ZnS
66ZnS
B0
5 645.8417(51)
5 588.9106150)
D0
0.0038472 (18)
0.0037701(17)
rms
0.013
0.016
Be
5 662.1143(81)
5 604.9376(80)
32.5452(71)
32.0540(73)
ae
De
0.0038372(29)
0.0037606(27)
-0.0000200(25)
-0.0000190(24)
be
re (Å)
2.0464
2.0464
-1
459
457
we (cm )
-1
2.09
2.07
wexe (cm )
DE,v=0 (eV)
3.12
3.12
67ZnS
68ZnS
5 561.6491(50)
0.0037339(17)
0.014
5 535.2749(50)
0.0036978(17)
0.010
a) In MHz unless otherwise indicated.
• Data fit using SPFIT (Pickett 1991)
• 7-8 transitions measured for 4 isotopologues
• Hyperfine structure from 67Zn (I = 5/2) not observed
• v = 0 and v = 1 for 64ZnS and 66ZnS
• re = 2.0464 Å (theory: re ~ 2.04-2.12 Å)
64th International Symposium on Molecular Spectroscopy
June 26, 2009
3d Sulfide and Oxide Bond Lengths
2.2
2.1

2 +

3
2.0
r (A)
“double-hump” structure
Sulfides

5

4 -

6 -
 
2

5

4
Oxides

3 -
1.7

2

2 +
1.6

3

5

4 -

6 -

5

4
1 +

1 +

3 -
1.5
Sc Ti V Cr Mn Fe Co Ni Cu Zn
r0: TiO, VO, CrO, MnO, FeO, CuO, ScS, VS, MnS, FeS, CoS
re: ScO, CoO, NiO, ZnO, TiS, CrS, NiS, CuS, ZnS
CuO-ZnO decrease: ~0.02 Å
CuS-ZnS decrease: ~0.003 Å
Less stabilization gained from
addition of electron to the
valence p orbital in ZnS
64th International Symposium on Molecular Spectroscopy
June 26, 2009
Dissociation Energy
Present Study
Peterson 2007
de Maria 1965
Boldyrev 1997
4
Energy (eV)
3
DE = 3.12 eV
• Value estimated in this work
higher than all previous
studies
• Is Morse potential good
assumption?
2
1
0
2.0
3.0
4.0
Bondlength (A)
5.0
DE (ZnS) = 3.12 eV
DE (ZnO) = 3.41 eV
DE (ZnF) = 3.12 eV
DE (ZnCl) = 2.73 eV
64th International Symposium on Molecular Spectroscopy
June 26, 2009
Summary
• Rotational spectra of four isotopologues of ZnS have been
measured
• Rotational and equilibrium constants have been determined
• This work agrees well with theory with regards to bond
lengths
• Dissociation energy is significantly higher than previous
theoretical and experimental (mass spec) studies indicate
• Similarities in bonding trends between oxides and sulfides
64th International Symposium on Molecular Spectroscopy
June 26, 2009
Acknowledgements
• Professor Lucy Ziurys
• Dr. DeWayne Halfen
• Robin Pulliam, Brent Harris, Ming Sun, Emmy Tenenbaum,
Jessica Dodd, Gilles Adande, Matthew Bucchino, and Jie Min
• Funding- NSF and NASA