Perturbation Analysis of the (0,0) Band of the A 2Π3/2 – X 2Σ+ transition in Zirconium Nitride, ZrN Kaitlin Womack, Taylor Dahms, Leah O’Brien Department of Chemistry Southern Illinois University Edwardsville Jessica Spencer and James O’Brien Department of Chemistry and Biochemistry University of Missouri – St. Louis

Previous Work: Bates & Dunn (1976) Observed A 2Π-X 2Σ+ Noted Strong Perturbations in A 2Π3/2 4 “gaps” in R21 and Q2 3 “gaps” in R2 and Q21 Suggested Perturbers 2Δ (x 2) Vibrational, from v=1 of A 2Π1/2 Bates, J.K.; Dunn, T. M. Can. J. Phys. 1976, 54, 1216-1223.

Bates, J.K.; Dunn, T. M. Can. J. Phys. 1976, 54, 1216-1223.

Previous Work: Cheung et al. Suggested possible perturbing states At high J 2Δ At low J 4Σ–3/2 Would split e/f levels differently Similar to TiN Perturbations found in all six branches Seven perturbations listed In the e-levels J′= 4.5 and 13.5 In the f-levels J′= 8.5 and 18.5 Both Λ-doubling components J′= 39.5, 44.5, and 56.5 Cheung, A. S-C.; Li, H.; Jiang, H.; Chen, H. J. Mol. Spectrosc. 2001, 210, 84-89.

Reduced Energy Plot for 2Π3/2 Excited State Rotational Energy E=BJ(J+1) Plot of E vs. J(J+1) Linear, with slope equal to B if unperturbed Cheung, A. S-C.; Li, H.; Jiang, H.; Chen, H. J. Mol. Spectrosc. 2001, 210, 84-89.

Experimental Design ZrN gas molecules produced in Zr-lined copper hollow cathode Applied discharge of 0.58A 1.45 torr of argon and helium trace amount of nitrogen

Experimental Design Spectra recorded using Bruker IFS125M Fourier transform spectrometer Resolution of 0.02 cm-1 Recorded 9,000-26,000 cm-1 region Data collection took approximately 2 weeks and over 8,000 scans

A 2Π3/2 – X 2Σ+ Spectra

Fitting the A 2Π1/2 –X 2Σ+ Transition Fit the A 2Π1/2 – X 2Σ+ component separately to determine ground state parameters Average residuals < 0.005 cm-1 Used PGOPHER, a spectral simulation and fitting program Ground state parameters held fixed when fitting the A 2Π3/2 – X 2Σ+ component

New Calculations by Zou: L-S States of ZrN Wenli Zou, Unpublished Work (2014)

Our Approach to Analysis of Perturbations Concentrate on the huge perturbations at low J Perturbers must be Ω = ½ since perturbation occurs at different J for e/f levels No 4Σ– state below 25,000 cm-1

Wenli Zou, Unpublished Work (2014) Vibrations of the 2Π state Vibrations of the 2Σ+ state Vibrations of the 4Π½ state Wenli Zou, Unpublished Work (2014)

Relevant Perturbations L±S± Spin-Orbit Same Ω and S, Different Σ and Λ Example: 2Π3/2 and 2Δ3/2 S-uncoupling Same Λ and S, Different Σ and Ω Example: 2Π3/2 and 2Π1/2 L-uncoupling Same Σ and S, Different Λ and Ω Example: 2Π3/2 and 2Δ5/2 or 2Π3/2 and 2Σ1/2, For the v=0 4Π½ perturbing state, use 2Π½ state and S- uncoupling interaction: B0~0.4003 cm-1 For the v=2 2Σ+ perturbing state, use L-uncoupling interaction: B2~0.4376 cm-1 Lefebvre-Brion, H.; Field, R.W. Perturbations in the Spectra of Diatomic Molecules Wenli Zou, unpublished work (2014)

PGOPHER and Perturbations Added two perturbers to excited manifold, selected appropriate interaction, gave initial T,B, γ, and p values Interaction is set to zero in this figure In the input file, changed rank of excited state at each perturbation Used Reduced Energy plot (right) to estimate crossings E-B2Π3/2J(J+1) vs J

Reduced Energy Plots e-levels f-levels

Optimize Interaction with Perturbers Molecular constants of the perturbing state are the same for e/f levels Value of interaction is different for e/f levels Needed to fit A 2Π3/2 - X 2Σ1/2 component separately Slowly (varied only 1 or 2 parameters at a time) fit data Ground state constants held fixed Fitted through J′= 49.5 Fit residuals near the perturbations < 0.1 cm-1 Other fit residuals < 0.02 cm-1

Deperturbed Molecular Constants

Simulated Spectra and Fortrat Diagrams

Experimental and Simulated Spectra

Summary Perturbations have been observed in the (0,0) band of the A 2Π3/2-X 2Σ+ transition of ZrN Perturbing states at low J’ identified as: v=2 of the (II) 2Σ+ state v=0 of the (I) 4Π½ state Deperturbed fit with molecular constants Average residual < 0.1 cm-1 No previous analysis of A 2Π3/2 New calculations by Wenli Zou invaluable B-values of perturbing states consistent with calculations This work in progress

Thank you for your attention! Acknowledgements Laboratory Groups Leah C. O’Brien: Kaitlin Womack and Taylor Dahms (SIU- Edwardsville) James J. O’Brien: Jessica Spencer (UM-St. Louis) National Science Foundation Wenli Zou (post-doc at Southern Methodist U) Thank you for your attention!

12s-> 6p ½ lower than 3/2 5p-> 12s 3/2 lower than 1/2

Comparison of Initial Fit with Previous Data X 2Σ+ B D x 107 γ x 103 γD x 107 This Work 0.482932(37) 4.73(12) -1.40(15) -7.32(99) aCheung et al. 0.482882(4) 4.53(1) -2.58(1) bBates & Dunn 0.4830(7) 6(1) -5(3) A 2Π1/2 T0 A 17400.3971(15) 567.02* 0.481019(38) 4.66(16) p pD x 107 H x 1011 -0.10561(10) 5.50(67) -3.83(19) Errors in parenthesis are one std. dev. * value held constant in fit a Cheung, A. S-C.; Li, H.; Jiang, H.; Chen, H. J. Mol. Spectrosc. 2001, 210, 84-89. b Bates, J.K.; Dunn, T. M. Can. J. Phys. 1976, 54, 1216-1223.