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The Pure Rotational Spectrum of KO

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1 The Pure Rotational Spectrum of KO
June 21st, 2017 2Π3/2 2Π1/2 2Σ1/2 + The Pure Rotational Spectrum of KO Mark A. Burton, Benjamin Russ, Phillip M. Sheridan, Matthew Bucchino, and Lucy M. Ziurys Department of Chemistry and Biochemistry, University of Arizona Department of Chemistry and Biochemistry, Canisius College Oxides Spectroscopic candy; halides horderves; carbides good stuff. KO is like an exotic bitter chocolate deceptive What we have done…and hopefully this leads to a more definitive understanding of KO.

2 KO, why? Periodic trends Astronomically Theory
June 21st, 2017 KO, why? Periodic trends KO is one remaining oxide not fully understood Astronomically KCl and KCN in IRC+10216 Theory Help understand interacting electronic states (~250 cm-1) Which is ground state? VY Canis Majoris 2Σ+

3 Chemistry of Alkali Monoxides
June 21st, 2017 Chemistry of Alkali Monoxides 2Σ+ ? 2Σ+ ground state Scattering Ionization technique Herm, R. R.; Herschbach, D. R. J. Chem. Phys. 1970, 52, 5783 Numerical Hartree-Fock and SDCI Langhoff, S. R.; Bauschlicher Jr., C. W.; Partridge, H. J. Chem. Phys. 1986, 84, 4474 High-level restricted coupled cluster with SO interactions Lee, E. P. F.; Soldán, P.; Wright, T. G. J. Chem. Phys. 2002, 117, 8241. Electron Spin Resonance Lindsay, D. M.; Herschbach, D. R.; Kwiram, A. L. J. Chem. Phys. 1974, 60, 315 Ultraviolet Photoelectron Spectroscopy Wright, T. G.; Ellis, A. M.; Dyke, J. M. J. Chem. Phys. 1993, 98, 2891 Ab initio (configuration interaction) Allison, J. N.; Goddard III, W. A. J. Chem. Phys. 1982, 77, 4259 2Π ground state

4 Millimeter/Submillimeter-wave Direct Absorption Spectroscopy
June 21st, 2017 Millimeter/Submillimeter-wave Direct Absorption Spectroscopy GHz ~1700 0C 110 MHz in 70 sec ±50 kHz resolution Binding energy D) reactant gas E) rooftop reflector F) Broida-type oven G) bolometer A) Frequency source B) polarizing grid C) pump outlet

5 Best reactions conditions: 2 mtorr N2O and 20 mtorr Ar, No discharge
June 21st, 2017 Best reactions conditions: 2 mtorr N2O and 20 mtorr Ar, No discharge Also tried N2O + discharge and O2 + discharge Liquid potassium Lots of contaminating lines! Expected large L-doubling (2P) and spin-rotation splittings (2S+)

6 June 21st, 2017 Troubles on the Job Process of collecting and identifying lines: 165 GHz Interaction between Ω = ½ states Potassium is very reactive Benjamin Russ Dr. DeWayne Halfen

7 Observed Millimeter-wave Transitions
June 21st, 2017 Observed Millimeter-wave Transitions J″ → J′ Λ-doubling νobs (MHz) νobs-νcalc 7.5 8.5 e -0.076 f 0.001 8.5 9.5 0.086 -0.150 9.5 10.5 -0.088 0.111 10.5 11.5 0.044 0.040 11.5 12.5 -0.002 0.099 12.5 13.5 -0.021 0.033 13.5 14.5 0.073 -0.077 14.5 15.5 -0.130 0.078 15.5 16.5 0.055 -0.132 16.5 17.5 -0.039 17.5 18.5 -0.120 0.169 J = 16.5 ← 15.5 J = 17.5 ← 16.5 J = 15.5 ← 14.5 H eff = H rot + H cd + H LD Hund’s Case A Frequency (MHz)

8 2Π3/2 Rotational Parameters
June 21st, 2017 2Π3/2 Rotational Parameters Parameter 2Π3/2 (MHz) B (57) DJ (28) HJ 1.770(42)x10-6 qeff (25) qD 2.78(56)x10-6 rms 0.100  r=2.336 Å re (Å) LiO (2Π) (2) NaO (2Π) (1) KO r3/2 = 2.336 RbO (2Σ+) (15) CsO (2Σ+) (16)

9 We need the 2Σ+ rotational transitions
June 21st, 2017 r3/2 = 2.336 2Π1/2 2Πi 2Σ+ 2Σ+ will have large Spin-Orbit interaction Is 2Π the ground state? We need the 2Σ+ rotational transitions 2Π3/2 2Σ+1/2 r3/2 = 2.330 *not to scale r1/2 = 2.261 Lee, E. P. F.; Soldán, P.; Wright, T. G. What is the Ground Electronic State of KO? J. Chem. Phys. 2002, 117, 8241.

10 Conclusions/Future Work
June 21st, 2017 Conclusions/Future Work Bond length is r3/2=2.326 Å 2Π3/2 may not be the ground state 2S+ will have large spin-orbit interaction Only controlled explosions = Lucy is happy Search for rotational transitions in the 2Π1/2 and 2Σ+1/2 states Record lower J transitions in 2Π3/2 state and resolve hyperfine Identify the ground state → LA-FTMW Conduct radioastronomical search for KO

11 NSF, NASA, University of Arizona, and Canisius College
June 21st, 2017 Acknowledgements Dr. Lucy Ziurys Dr. DeWayne Halfen Dr. Phil Sheridan Dr. Matthew Bucchino Benjamin Russ Kyle Kilchenstein John Keogh Debbie Schmidt Tyler Hermann Jacob Bernal NSF, NASA, University of Arizona, and Canisius College

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13 Fourier Transform Microwave (FTMW)
Carrier Gas Laser Pulse Poppet Sample Rod Low Noise Amplifier Computer Pulsed Valve figure modified from: Sun, M.; Halfen, D. T.; et. al. The Rotational Spectrum of CuCCH: A Fourier Transform Microwave Discharge Assisted Laser Ablation Spectroscopy and Millimeter/Submillimeter Study. J. Chem. Phys, 2010, 133,

14 17.5  16.5 16.5  15.5 15.5  14.5

15 Is 2Π the ground state? We need the 2Σ+ June 21st, 2017
Lee, E. P. F.; Soldán, P.; Wright, T. G. What is the Ground Electronic State of KO? J. Chem. Phys. 117, 8241.


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