1. CALIFORNIA INSTITUTE OF TECHNOLOGY PURE ROTATIONAL SPECTROSCOPY OF PANHs: 1,10-PHENANTHROLINE Brett A. McGuire, Ian A. Finneran, P. Brandon Carroll, & Geoffrey A. Blake

2. INTRODUCTION Why PA(N)Hs?

3. INTRODUCTION Why PA(N)Hs? - Prolific in the ISM

4. INTRODUCTION Why PA(N)Hs? - Only two definitively identified (C 60 & C 70 ) - Prolific in the ISM

5. INTRODUCTION Why PA(N)Hs? - Fascinating dynamical systems - Prolific in the ISM - Only two definitively identified (C 60 & C 70 )

6. INTRODUCTION Why PA(N)Hs? - Testbeds for FIR large amplitude motion studies - Prolific in the ISM - Only two definitively identified (C 60 & C 70 ) - Fascinating dynamical systems

7. INTRODUCTION Why PA(N)Hs? - Prolific in the ISM - Only two definitively identified (C 60 & C 70 ) - Fascinating dynamical systems - Testbeds for FIR large amplitude motion studies 1,10-phenanthrolineAcridinePhenanthridine

8. INTRODUCTION Why (These) PANHs? 1,10-phenanthrolineAcridinePhenanthridine - Large dipole moments - Comparatively small and simple - Rigid structure simplifies spectral analysis - Previous rotational studies below 85 GHz

9. INTRODUCTION - ASTROCHEMISTRY PA(N)Hs are ubiquitous in the ISM

10. INTRODUCTION - ASTROCHEMISTRY PA(N)Hs are ubiquitous in the ISM Aromatic Skeleton C2H2C2H2 C2H2C2H2 C2H2C2H2 C2H2C2H2 PAHs

11. INTRODUCTION - ASTROCHEMISTRY PA(N)Hs are ubiquitous in the ISM Aromatic Skeleton C2H2C2H2 C2H2C2H2 C2H2C2H2 C2H2C2H2 PAHs Aromatic Skeleton C2H2C2H2 HCNC2H2C2H2 PANHs

12. INTRODUCTION - ASTROCHEMISTRY PA(N)Hs are ubiquitous in the ISM Aromatic Skeleton C2H2C2H2 C2H2C2H2 C2H2C2H2 C2H2C2H2 PAHs Aromatic Skeleton C2H2C2H2 HCNC2H2C2H2 PANHs Size distribution, charge, and C/N fraction dependent on: - Local N budget - UV Radiation Flux - Temperature - Density

13. INTRODUCTION - ASTROCHEMISTRY PA(N)H spectra are ambiguous Figure from Peeters 2011, Proc. IAU Sym 280, adapted from Cami et al. 2011, EAS Pubs,46, 117 Simulated Observed Residual Can reproduce observed PA(N)H features with astonishingly good fits using the entire NASA Ames PAH Spectral Database 6.2 µm 7.7 µm 11.0 µm 11.2 µm PANHs Size Distr. Neutral PAHs PAH Cations Lack any molecular specificity

14. INTRODUCTION - ASTROCHEMISTRY PA(N)H spectra are ambiguous Simulated Observed Residual Can reproduce observed PA(N)H features with astonishingly good fits using the entire NASA Ames PAH Spectral Database 6.2 µm 7.7 µm 11.0 µm 11.2 µm PANHs Size Distr. Neutral PAHs PAH Cations Lack any molecular specificity Need 1) Foundational observations for targeted searches with ALMA 2) Laboratory rotational spectra Figure from Peeters 2011, Proc. IAU Sym 280, adapted from Cami et al. 2011, EAS Pubs,46, 117

15. INTRODUCTION - PROPOSED OBSERVATIONS NGC 2023 15 – 18 μm emission in target region - associated with neutral poly-aromatics 6 m primary beam~ 120” 10 m primary beam~ 75” Mosaic coverage~ 75” Synthesized beam~ 5” x 4” Figures adapted from Peeters et al. 2012, ApJ, 747, 44. CARMA Array (Owens Valley, CA) Targeting HCN, HCO +, & CO In: NGC 2023 - Reflection Nebula (RN) L134 N - Cold, Dark Molecular Cloud GGD 27 - ILL - Illuminating Source for a RN IRAC [8.0] Surface Brightness

16. AB INITIO CALCULATIONS – NEUTRAL PANHS Laboratory studies of larger and larger PA(N)Hs will become impractical in the mm and submm Low temperature mw studies will help, but will need excellent theory

17. Laboratory studies of larger and larger PA(N)Hs will become impractical in the mm and submm Low temperature mw studies will help, but will need excellent theory Previous studies 1 show good agreement with experiment for: Structures, Rotational Constants: B3LYP/cc-pVTZ Distortion Constants:B3LYP/6-311++G** SCF/DZP (w/ ACESII) Are there better methods? 1 McNaughton et al. 2008, ApJ, 678, 309 AB INITIO CALCULATIONS – NEUTRAL PANHS

18. 2 Steber 2011, 66th Mol Spec Conference 1 Zhao 2008, Theor Chem Account, 120, 215 M06-2X? - DFT method - improvement on B3LYP 1 - Optimized to better handle long-range interactions on main group atoms - Shown to have an excellent cost-benefit ratio for structures and energies (specifically of clusters and larger species) 2 AB INITIO CALCULATIONS – NEUTRAL PANHS

19. McNaughton et al. 2008, ApJ, 678, 309 Acridine Constant B3LYP/6- 311++G** MP2/ 6-311++G** M062X/ 6-31G M062X/ 6-31+G** M062X/ 6-311++G** Rotational0.14(0.10)0.51(0.06)0.31(0.10)0.18(0.08)0.50(0.07) Distortion3.99(2.87)5.47(6.61)4.60(2.87)3.99(2.58) Phenanthroline Constant B3LYP/6- 311++G** MP2/ 6-311++G** M062X/ 6-31G M062X/ 6-31+G** M062X/ 6-311++G** Rotational0.24(0.09)0.49(0.04)0.37(0.29)0.17(0.07)0.50(0.10) Distortion15.64(24.78)8.63(2.90)10.49(11.08)49.01(84.25) Phenanthridine Constant B3LYP/6- 311++G** (SCF/DZP) MP2/ 6-311++G** M062X/ 6-31G M062X/ 6-31+G** M062X/ 6-311++G** Rotational0.16(0.13)0.49(0.01)0.16(0.11)0.18(0.16)0.48(0.15) Distortion11.82(0.58)7.54(0.40)2.67(0.44)5.06(1.17) x 100% Exp Exp - Calc AB INITIO CALCULATIONS – NEUTRAL PANHS

20. McNaughton et al. 2008, ApJ, 678, 309 Conclusion? M062X/6-31+G** - Same or better accuracy on A, B, C - Extremely fast - Same or better accuracy on distortion constants without resorting to additional calculations x 100% Exp Exp - Calc AB INITIO CALCULATIONS – NEUTRAL PANHS Acridine Constant B3LYP/6- 311++G** MP2/ 6-311++G** M062X/ 6-31G M062X/ 6-31+G** M062X/ 6-311++G** Rotational0.14(0.10)0.51(0.06)0.31(0.10)0.18(0.08)0.50(0.07) Distortion3.99(2.87)5.47(6.61)4.60(2.87)3.99(2.58) Phenanthroline Constant B3LYP/6- 311++G** MP2/ 6-311++G** M062X/ 6-31G M062X/ 6-31+G** M062X/ 6-311++G** Rotational0.24(0.09)0.49(0.04)0.37(0.29)0.17(0.07)0.50(0.10) Distortion15.64(24.78)8.63(2.90)10.49(11.08)49.01(84.25) Phenanthridine Constant B3LYP/6- 311++G** (SCF/DZP) MP2/ 6-311++G** M062X/ 6-31G M062X/ 6-31+G** M062X/ 6-311++G** Rotational0.16(0.13)0.49(0.01)0.16(0.11)0.18(0.16)0.48(0.15) Distortion11.82(0.58)7.54(0.40)2.67(0.44)5.06(1.17)

21. SPECTROSCOPY - EXPERIMENTAL APPROACHES Spectra of these molecules at higher frequencies is essential for accurate evaluation of distortion constants

22. BACKGROUND - PROTONATED PANHS Protonated PANHs

23. BACKGROUND - PROTONATED PANHS Protonated PANHs - Fundamentally interesting for spectroscopic and dynamical studies (protonation dynamics, proton roaming...) - Known to be a major constituent of observed PA(N)H emission

24. THEORY - PROTONATED PHENANTHROLINE 0 kcal/mol Energy M062X/6-311++G**

25. THEORY - PROTONATED PHENANTHROLINE -184.04 kcal/mol -174.90 kcal/mol -180.57 kcal/mol 0 kcal/mol Energy -188.74 kcal/mol -192.31 kcal/mol M062X/6-311++G**

26. THEORY - PROTONATED PHENANTHROLINE -244.94 kcal/mol -189.65 kcal/mol Energy -192.31 kcal/mol -188.74 kcal/mol -184.04 kcal/mol -174.90 kcal/mol -180.57 kcal/mol -244.94 kcal/mol M062X/6-311++G** 0 kcal/mol

27. THEORY - PROTONATED PHENANTHROLINE -244.94 kcal/mol Energy -192.31 kcal/mol -188.74 kcal/mol -184.04 kcal/mol -174.90 kcal/mol -180.57 kcal/mol -244.94 kcal/mol M062X/6-311++G** -189.65 kcal/mol T.S. 0 kcal/mol

28. Still require spectra of neutral precursors... THEORY - PROTONATED PHENANTHROLINE

29. BACKGROUND - PANH-WATER CLUSTERS PANH - Water Clusters

30. BACKGROUND - PANH-WATER CLUSTERS - Spectroscopically interesting - Potentially relevant to grain - water interactions in interstellar dusts and ices - Applications to coherent control of large amplitude motions PANH - Water Clusters

31. COMPUTATIONAL STUDIES - PANH-WATER MP2 6-311++G** M06-2X 6-311++G** A (MHz)956.20970.33 B (MHz)462.41466.46 C (MHz)312.55315.56 ΔJ (KHz)0.003 ΔK (KHz)-0.384 ΔJK (KHz)0.518 H 2 O in-plane wag (cm -1 )2132 H 2 O stretch (cm -1 )3439 N-H Bond (Å)1.9371.924 C-N-O Angle (°)115.3113.7 Binding Energy (kcal/mol) 8.48.5 Lit = 7.6 Mitsui et al. 2000, Chem Phys Lett, 317, 211 For more on THz coherent control: Doslic 2006, J. Phys. Chem. A., 110, 12400 - Theoretical Jewriya et al. 2010, PRL, 105, 203003 - Experimental

32. COMPUTATIONAL STUDIES - PANH-WATER Phenanthridine M06-2X 6-311++G** A (MHz)745.22 B (MHz)542.77 C (MHz)314.24 N-H Bond (Å)1.954 Binding Energy (kcal/mol) 7.7 Phenanthroline M06-2X 6-311++G** A (MHz)854.60 B (MHz)580.86 C (MHz)345.81 N-H Bond (Å)2.158 Binding Energy (kcal/mol) 9.6

33. COMPUTATIONAL STUDIES - PANH-WATER Still require spectra of monomeric precursors...

34. SPECTROSCOPY - EXPERIMENTAL APPROACHES 10 - 100 mTorr / 25 - 100 °C H 2 O outH 2 O in Sample To Vac 75 - 120 GHz To Computer H 2 O outH 2 O in Ar in To Vac 75 - 120 GHz To Computer Ar + Sample 100 °C

35. SPECTROSCOPY - EXPERIMENTAL APPROACHES 10 - 100 mTorr / 25 - 100 °C H 2 O outH 2 O in Sample To Vac 75 - 120 GHz To Computer H 2 O outH 2 O in Ar in To Vac 75 - 120 GHz To Computer Ar + Sample 100 °C Cold

36. SPECTROSCOPY - EXPERIMENTAL APPROACHES Rooftop Reflector 1 mm Pinhole Copper Sheath Cartridge Heaters Ar In Wire Mesh Solid Sample

37. SPECTROSCOPY - EXPERIMENTAL APPROACHES 75 - 120 GHz H 2 O outH 2 O in To Vac Still Cold 100 °C To Computer Wire Grid Polarizer Ar + Sample Still Cold Configured for both continuous flow and pulsed operation

38. SPECTROSCOPY - EXPERIMENTAL APPROACHES 525 - 565 GHz To Computer To Vac Sample 1 - 8 mTorr / 25 °C 75 - 120 GHz To Computer To Vac Sample 1 - 8 mTorr / 40 °C

39. SPECTROSCOPY - PRELIMINARY DATA M

40. M

41. M

42. M

43. No match in any database to any molecule previously run in this cell, nor to any collected spectra A promising start, but impossible to determine w/o low frequency data