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

University of Wisconsin–Madison Previous Work Bouchy and Roussy (1977) Kasten and Dreizler (1987) A (MHz) 5202.3 (4) 5202.103 (46) B (MHz) 972.685 (7) 972.68072 (62) C (MHz) 819.623 (8) 819.62766 (61) ΔJ (kHz) 0.068 (4) 0.0689 (11) ΔJK (kHz) -0.208 (30) -0.209 (16) ΔK (kHz) [0] δJ (kHz) 0.015 (5) 0.01210 (77) δK (kHz) n 59 15 σ (MHz) 0.074 0.009 Freq range 8-40 GHz 4.7-8.0 GHz J range 5-21 3-15 Kprolate range 0-10 0-3 A. Bouchy and G. Roussy, Journal of Molecular Spectroscopy. 65 (1977), 395-404. W. Kasten and H. Dreizler, Z. Naturforsch. 42a (1987), 79-82. 6/22/2015 University of Wisconsin–Madison

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

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

University of Wisconsin–Madison Ground State A (MHz) 5201.859 (11) B (MHz) 972.68315 (31) C (MHz) 819.62477 (34) DJ (kHz) 0.068490 (10) DJK (kHz) -0.20693 (32) DK (kHz) 3.5052 (89) d1 (kHz) -0.0167059 (46) d2 (kHz) -0.0020304 (22) HJ (Hz) 0.00003115 (25) HJK (Hz) -0.0012043 (90) HKJ (Hz) 0.01663 (23) HK (Hz) [0] h1 (Hz) 0.000011590 (59) h2 (Hz) 0.000001024 (75) h3 (Hz) 0.0000006860 (51) LJ (mHz) -0.0000000106 (24) LJJK (mHz) 0.00000360 (10) LJK (mHz) -0.0001769 (30) LKKJ (mHz) -0.004443 (71) LK (mHz) [0] l1 (mHz) l2 (mHz) 0.00000000801 (76) l3 (mHz) l4 (mHz) n = 3087, σ = 0.049 MHz 6/22/2015 University of Wisconsin–Madison

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

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

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

University of Wisconsin–Madison ν36 Bouchy and Roussy Current Work A (MHz) 5144.6(3) B (MHz) 972.788(6) C (MHz) 821.139(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) 5144.068 (75) B (MHz) 972.7846 (15) C (MHz) 821.1426 (10) DJ (kHz) 0.070593 (31) DJK (kHz) -0.1550 (14) DK (kHz) -0.49 (17) d1 (kHz) -0.016615 (20) d2 (kHz) -0.001366 (14) HJ (Hz) 0.00002975 (42) HJK (Hz) -0.000619 (70) HKJ (Hz) 0.03018 (80) HK (Hz) -1.30 (13) h1 (Hz) 0.00001434 (31) h2 (Hz) -0.00000067 (53) h3 (Hz) -0.000001218 (47) LJ (mHz) [0] LJJK (mHz) 0.00000681 (71) LJK (mHz) -0.000502 (11) LKKJ (mHz) -0.00452 (24) LK (mHz) l1 (mHz) l2 (mHz) 0.0000000399 (66) l3 (mHz) l4 (mHz) n = 1606, σ = 0.171 MHz 6/22/2015 University of Wisconsin–Madison

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

University of Wisconsin–Madison ν25 ~ 95 cm-1 Bouchy and Roussy Current Work A (MHz) 5263.4(5) B (MHz) 972.955(9) C (MHz) 819.495(9) ΔJ (kHz) 0.0716(7) ΔJK (kHz) [0] ΔK (kHz) δJ (kHz) 0.015(6) n 27 σ (MHz) 0.094 A (MHz) 5263.55 (10) B (MHz) 972.9536 (11) C (MHz) 819.49283 (51) DJ (kHz) 0.06343 (69) DJK (kHz) [0] DK (kHz) 52.8 (19) d1 (kHz) -0.01468 (46) d2 (kHz) -0.00327 (11) HJ (Hz) 0.00001559 (17) HJK (Hz) -0.000559 (65) HKJ (Hz) 0.4425 (83) n = 377, σ = 0.055 MHz 6/22/2015 University of Wisconsin–Madison

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

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) 5096.08 (30) B (MHz) 973.0122 (17) C (MHz) 822.5376 (16) DJ (kHz) 0.05803 (10) DJK (kHz) [0] DK (kHz) d1 (kHz) -0.006970 (60) d2 (kHz) 0.0014931 (82) HJ (Hz) 0.00001442 (51) HJK (Hz) -0.005104 (95) n = 291, σ = 0.099 MHz 6/22/2015 University of Wisconsin–Madison

University of Wisconsin–Madison ν25 ~ 95 cm-1 2ν36 ~ 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

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

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

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

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

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

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

Higher Energy Vibrational States Bouchy and Roussy Current Work 3ν36 A (MHz) 5048 (2) B (MHz) 973.34 (2) C (MHz) 823.87 (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) 5013.8 (23) 5205.793 5148.035 B (MHz) 973.218 (22) 971.175 (63) 974.543 (33) C (MHz) 823.7975 (46) 821.1399 (17) 822.1937 (53) DJ (kHz) 0.04785 (85) 0.1496 (43) 0.1135 (17) DJK (kHz) [0] -6.84 (32) -2.49 (12) DK (kHz) d1 (kHz) -0.00112 (53) -0.0544 (21) -0.03734 (90) d2 (kHz) 0.00338 (10) HJ (Hz) 0.0000113 (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

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

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