1. Millimeter-Wave Spectroscopy of Phenyl Isocyanate
Cara E. Schwarz, Brent K. Amberger, Benjamin C. Haenni, Brian J. Esselman, R. Claude Woods, and Robert J. McMahon
6/22/2015
University of Wisconsin–Madison

2. University of Wisconsin–Madison
Previous Work
Bouchy and Roussy (1977)
Kasten and Dreizler (1987)
A (MHz)
(4)
(46)
B (MHz)
(7)
(62)
C (MHz)
(8)
(61)
ΔJ (kHz)
0.068 (4)
(11)
ΔJK (kHz)
(30)
(16)
ΔK (kHz)
[0]
δJ (kHz)
0.015 (5)
(77)
δK (kHz) n 59 15
σ (MHz)
0.074
0.009
Freq range
8-40 GHz
GHz
J range
5-21
3-15
Kprolate range
0-10
0-3
A. Bouchy and G. Roussy, Journal of Molecular Spectroscopy. 65 (1977),
W. Kasten and H. Dreizler, Z. Naturforsch. 42a (1987),
6/22/2015
University of Wisconsin–Madison

3. University of Wisconsin–Madison
mm-Wave Spectrum
Chosen to test how large of a molecule could be done with our spectrometer
Our group is looking at various 6pi electron aromatic molecules
Well outside the maximum intensity region of the spectrum
High Js as a result, which means distortion constants are very important
μa = 2.50 ± 0.02 D
μb ≤ 0.2 D
6/22/2015
University of Wisconsin–Madison

4. University of Wisconsin–Madison
aR01
Very dense spectrum, low energy vibrational states
Went up to about K40 and saw effects of perturbations
6/22/2015
University of Wisconsin–Madison 5 6 7 8 9 10 11 2 3 1 5 6 4

5. University of Wisconsin–Madison
Ground State
A (MHz)
(11)
B (MHz)
(31)
C (MHz)
(34)
DJ (kHz)
(10)
DJK (kHz)
(32)
DK (kHz)
(89)
d1 (kHz)
(46)
d2 (kHz)
(22)
HJ (Hz)
(25)
HJK (Hz)
(90)
HKJ (Hz)
(23)
HK (Hz)
[0]
h1 (Hz)
(59)
h2 (Hz)
(75)
h3 (Hz)
(51)
LJ (mHz)
(24)
LJJK (mHz)
(10)
LJK (mHz)
(30)
LKKJ (mHz)
(71)
LK (mHz)
[0]
l1 (mHz)
l2 (mHz)
(76)
l3 (mHz)
l4 (mHz)
n = 3087, σ = MHz
6/22/2015
University of Wisconsin–Madison

9. University of Wisconsin–Madison
Ground State Overview
Lines up to Kprolate ~ 40 have been confidently assigned
Perturbations occur at higher K values
Precise determination of rotational constants
Quartic, partial sextic and octic centrifugal distortion analysis
6/22/2015
University of Wisconsin–Madison

10. University of Wisconsin–Madison
Vibrational States
2ν36+ν25 – A’
4ν36 – A’
2ν25 – A’
3ν36 – A’’
ν36+ν25 – A’’
ν36 ~ 47 cm-1
A’’
2ν36 – A’
ν25 – A’
all are very low energy meaning they’re very intense – boltzmann?
very close in energy, particularly v25 and 2v36 which are predicted to have nearly identical energies
ν25 ~ 95 cm-1 A’
ν36 – A’’ A’
6/22/2015
University of Wisconsin–Madison
CCSD(T)/ANO0

11. K = 6 K = 11 K = 8 K = 5 K = 4 K = 3 K = 10 K = 2 K = 7 K = 9 K = 1
v36
centered on K0 of the ground state
lines are approximately 1600 MHz apart
clearly lots of random lines
K = 9
K = 1
K = 0

12. University of Wisconsin–Madison
ν36
Bouchy and Roussy
Current Work
A (MHz)
5144.6(3)
B (MHz)
(6)
C (MHz)
(6)
ΔJ (kHz)
0.071(4)
ΔJK (kHz)
0.157(56)
ΔK (kHz)
[0]
δJ (kHz)
0.018(4) n 42
σ (MHz)
0.061
A (MHz)
(75)
B (MHz)
(15)
C (MHz)
(10)
DJ (kHz)
(31)
DJK (kHz)
(14)
DK (kHz)
-0.49 (17)
d1 (kHz)
(20)
d2 (kHz)
(14)
HJ (Hz)
(42)
HJK (Hz)
(70)
HKJ (Hz)
(80)
HK (Hz)
-1.30 (13)
h1 (Hz)
(31)
h2 (Hz)
(53)
h3 (Hz)
(47)
LJ (mHz)
[0]
LJJK (mHz)
(71)
LJK (mHz)
(11)
LKKJ (mHz)
(24)
LK (mHz)
l1 (mHz)
l2 (mHz)
(66)
l3 (mHz)
l4 (mHz)
n = 1606, σ = MHz
6/22/2015
University of Wisconsin–Madison

13. University of Wisconsin–Madison
K = 0
K = 1
K = 2
K = 3
K = 4
K = 5
K = 6
v8 LW
v25
12/1/2018
University of Wisconsin–Madison

14. University of Wisconsin–Madison
ν25 ~ 95 cm-1
Bouchy and Roussy
Current Work
A (MHz)
5263.4(5)
B (MHz)
(9)
C (MHz)
(9)
ΔJ (kHz)
0.0716(7)
ΔJK (kHz)
[0]
ΔK (kHz)
δJ (kHz)
0.015(6) n 27
σ (MHz)
0.094
A (MHz)
(10)
B (MHz)
(11)
C (MHz)
(51)
DJ (kHz)
(69)
DJK (kHz)
[0]
DK (kHz)
52.8 (19)
d1 (kHz)
(46)
d2 (kHz)
(11)
HJ (Hz)
(17)
HJK (Hz)
(65)
HKJ (Hz)
(83)
n = 377, σ = MHz
6/22/2015
University of Wisconsin–Madison

15. University of Wisconsin–Madison
K = 4
K = 3
K = 2
K = 1
K = 0
2v7 LW
2v36
6/22/2015
University of Wisconsin–Madison

16. University of Wisconsin–Madison
2ν36 ~ 95 cm-1
Bouchy and Roussy
Current Work
A (MHz)
5096.5(6)
B (MHz)
973.03(1)
C (MHz)
822.53(2)
ΔJ (kHz)
0.088(19) n 25
σ (MHz)
0.085
A (MHz)
(30)
B (MHz)
(17)
C (MHz)
(16)
DJ (kHz)
(10)
DJK (kHz)
[0]
DK (kHz)
d1 (kHz)
(60)
d2 (kHz)
(82)
HJ (Hz)
(51)
HJK (Hz)
(95)
n = 291, σ = MHz
6/22/2015
University of Wisconsin–Madison

17. University of Wisconsin–Madison
ν25 ~ 95 cm ν36 ~ 95 cm-1
Both states are predicted to have energies of ~95 wavenumbers
Both states are symmetric
Initial guess was Fermi resonance… but deltaK isn’t 0
deltaK =2, so F-type Coriolis perturbation
6/22/2015
University of Wisconsin–Madison

18. University of Wisconsin–Madison
K = 4 Obs-Calc for ν25 and 2ν36
ν25
2ν36
6/22/2015
University of Wisconsin–Madison

19. University of Wisconsin–Madison
ν25, 2ν36
Through analyzing the errors in the predictions, we discovered that the perturbations follow ΔK = 2 selection rules. It is expected that ν25 is the lower energy state
6/22/2015
University of Wisconsin–Madison

20. University of Wisconsin–Madison
ν25, 2ν36
6/22/2015
University of Wisconsin–Madison

21. University of Wisconsin–Madison
ν25, 2ν36
peak in the graph is consistently around J ~170
6/22/2015
University of Wisconsin–Madison

22. University of Wisconsin–Madison
3ν36
mm-Wave experimental data and extrapolation
Microwave value
6/22/2015
University of Wisconsin–Madison

23. University of Wisconsin–Madison
K = 1
K = 3
K = 2
K = 0
6/22/2015
University of Wisconsin–Madison

24. Higher Energy Vibrational States
Bouchy and Roussy
Current Work
3ν36
A (MHz)
5048 (2)
B (MHz)
(2)
C (MHz)
(2)
ΔJ (kHz)
0.069 (15)
ΔJK (kHz)
[0]
ΔK (kHz)
δJ (kHz)
0.029(10) n 14
σ (MHz)
0.120
3ν36 ~ 142 cm-1
ν36 + ν25 ~ 142 cm-1
2ν36 + ν25 ~ 190 cm-1
A (MHz)
(23)
B (MHz)
(22)
(63)
(33)
C (MHz)
(46)
(17)
(53)
DJ (kHz)
(85)
(43)
(17)
DJK (kHz)
[0]
-6.84 (32)
-2.49 (12)
DK (kHz)
d1 (kHz)
(53)
(21)
(90)
d2 (kHz)
(10)
HJ (Hz)
(17) n
242
194
376
σ (MHz)
0.998
0.495
0.635
How the 3v7 ABC were predicted (microwave data wasn’t very useful)
Unidentified state from 1977 paper - vx
6/22/2015
University of Wisconsin–Madison

25. University of Wisconsin–Madison
Conclusions
Excellent fits for the ground state and ν36 up to Kprolate ~ 40 then the spectrum shows effects of perturbations
Perturbations between ν25 and 2ν36 are evident at much lower values of Kprolate
Not the result of Fermi resonance as initially expected
2nd order Coriolis resonance (F)
6/22/2015
University of Wisconsin–Madison

26. University of Wisconsin–Madison
Thanks!
Research group members:
Professor Robert J. McMahon
Professor R. Claude Woods – FE01
Dr. Brian Esselman
Brent Amberger – FE02
Ben Haenni
Stephanie Knezz – RJ13
Nick Walters – FE06
Vanessa Orr
Zach Heim
Maria Zdanovskaia
Matisha Kirkconnell
6/22/2015
University of Wisconsin–Madison