1. Spectroscopy of the Low- Energy States of BaO + Joshua H. Bartlett, Robert A. VanGundy, Michael C. Heaven 70 th International Symposium on Molecular Spectroscopy June 26 th, 2015

2. Overview Background Experimental Set-up Previous research 69 th ISMS Presentation RH05 Study Completion

3. Motivation Theoretical studies: Ground state switch in Alkaline Earth Oxide ions Laser Cooling and Ion Trapping: Analogous to Alkali metals Can be manipulated using external fields Lack of spectroscopic data for BaO + Benchmark calculations Refining the Ionization Potential

4. Conditions and Methods Laser Ablation of a pure barium rod Supersonic Expansion Carrier gas 1% O 2 in He Lambda Physik: Scan Mate Pro 0.15cm -1 linewidth, 10ns pulse Continuum: ND6000 0.1cm -1 linewidth, 10ns pulse Laser Induced Fluorescence(LIF), Resonantly Enhanced Multiphoton Ionization(REMPI), Zero Kinetic Energy Photoelectron Spectroscopy(ZEKE)

5. Experimental Schematic PMT Drift Tube Gas in: 0.5-2% O 2 in He Microchannel Plate Detectors Ablation Laser First Laser Chamber 1: ~5x10 -6 torr Chamber 2: ~1x10 -8 torr Second Laser Skimmer Charged Plates

6. PFI-ZEKE Electron Spectroscopy *

7. Previous Work Previously reported 1 BaO transitions used A 1 ∑ + -X 1 ∑ + v’=5-8 Photoelectron spectroscopy 2 : ionization potential 6.46(7) eV 1 (52,103 ± 565 cm -1 ) RH05, 69 th ISMS Using Zero Kinetic Energy Electron Spectroscopy (ZEKE) BaO + 0-0 at 54984(1) cm -1 using v’=6 of BaO A-X BaO + 1-0 at 55513(1) cm -1 1.H. Li, C. Focsa, B. Pinchemel, R. J. Le Roy, and P. F. Bernath, J. Chem. Phys. 113, 3026 (2000). 2.J. M. Dyke, M. Feher, B. W. J. Gravenor, and A. Morris, J. Phys. Chem. 91, 4476 (1987).

8. BaO + Origin Band

9. New Results From BaO A-X v’=8 BaO + X,v + =0-4 X 2 ∑ + BaO + A 3/2 and A 1/2 v + =0-2 A 2 ∏ Further Investigation of BaO + 0-0 Complex PFI-ZEKE spectrum Two-dimensional approach

10. Select bands of BaO +

11. 137,136,135,134 BaO R bandheads Fluorescence BaO A-X 8-0 by LIF T rot =15K P8 P4 R bandhead 138 BaO

12. PFI-ZEKE using A-X 8-0 band 34352cm -1 34344cm -1 Second Photon Energy /cm -1

13. Feature at 34352cm -1 Intermediate Laser Energy /cm -1

14. Feature at 34344cm -1 Intermediate Laser Energy /cm -1

15. PFI-ZEKE using A-X 8-0 band Second Photon Energy /cm -1 J ’ -J +

16. BaO + A 2 ∏ 3/2 v + =0 Energy Relative to BaO + X 2 ∑ + v + = 0

17. Constants Experimental constants for BaO + in cm -1 BaO + T0T0 ωeωe ωeχeωeχe B0+B0+ X2∑+X2∑+ 0.0547.3(24)1.8(4)0.281 A 2 ∏ 3/2 1482(2)506(4)- A 2 ∏ 1/2 1696(2)506(4)- X2∑+X2∑+ B0+B0+ ωeωe ωeχeωeχe MRCI+Q/SO( I) 0.2674555.61.55 MRCI+Q/SO( II) 537.42.20 CCSD(T) 559.72.04 DFT/B3LYP 542.81.71 A2∏A2∏T0T0 ωeωe ωeχeωeχe MRCI+Q/SO(I ) Ω 3/2 937.1505.61.81 MRCI+Q/SO(I ) Ω 1/2 1121.8506.01.80 MRCI+Q/SO(I I) Ω 3/2 1142.7470.13.71 MRCI+Q/SO(I I) Ω 1/2 1259.9466.22.40 CCSD(T) 1215.9514.61.92 DFT/B3LYP 796.7508.21.79 Calculated constants for BaO + in cm -1 MRCI(1) used Roos ANO for Ba and O, MRCI(2) used Roos ANO for O, ECP46MWB for Ba

18. Project Conclusion Established Ionization potential with low error 6.8123(3) eV (54944(3) cm -1 ) Observed BaO + Transitions X 2 ∑ + v = 0-5 A 2 ∏ 3/2-1/2 v = 0-2 Identified high J contributions to BaO X v=0 Next Step BaCl/BaCl + ✔ CaO/CaO +

19. Acknowledgements Joshua Bartlett Dr. Michael Heaven The Heaven Group Dr. Adrian Gardner Dr. Jacob Stewart Dr. Jiande Han Kyle Mascaritolo Michael Sullivan Amanda Dermer NSF Thank you very much!