1. Water network-mediated, electron induced proton transfer in anionic [C 5 H 5 N·(H 2 O) n ]¯ clusters: Size-dependent formation of the pyridinium radical for n ≥ 3 Andrew F. DeBlase, Conrad Wolke, Gary H. Weddle, Kaye A. Archer, Kenneth D. Jordan, John T. Kelly, Gregory S. Tschumper, Nathan I. Hammer, and Mark A. Johnson International Symposium on Molecular Spectroscopy June 24, 2015

2. Proton Transfer Relays in CO 2 Reduction Simulations show water networks play a role in stabilizing pyridinium radical Bocarsly J. Am. Chem. Soc. 2008. Bocarsly J. Am. Chem. Soc. 2011 Pyridine catalyzes reduction of CO 2 to transportable fuels (i.e. formic acid) Experimental evidence for stabilization of pyridine radical by water network? CO 2 does bind to Py in the gas phase: Kamrath J. Am. Chem. Soc. 2010 C-N stretch at 1283 cm -1 Musgrave J. Am. Chem. Soc. 2012 Py

3. Introducing the Hydrated Electron: A Powerful Reducing Agent in Cluster Chemistry How do small H 2 O clusters bind an e - ? Hammer, et al. Science 2004 e.g. (H 2 O) n ¯ + CH 3 CN → OH¯∙(H 2 O) n-m-1 + m H 2 O + CH 3 CHN ∙ Py + (H 2 O) n ¯ → Py·(H 2 O) n ¯ → PyH·(H 2 O) n-1 ·OH¯ Can we use the hydrated electron to reduce Py to PyH (0) ? Beyer, M. K., et al. Angew. Chem. Int. Ed. 2003, 42, 5516.

4. Ion Optics 2m Flight Tube Wiley- McLaren TOF Reflectron Pulsed Valve Electron Gun MCP Detector Nd:YAG OPO/OPA The Jet Source 10 -5 Torr3 × 10 3 Torr e-e- Solenoid Ar h k IVR k evap A + ∙Ar n + h ν → A + ∙Ar n-m + m Ar 60 psi Ar with trace Py and H 2 O vapors

5. Py·(H 2 O) n Mass Spectrum 100120140160180200220 m/z n =345678 3456 [Py∙(H 2 O) n ] ¯ [Py∙(H 2 O) n ] ¯∙ Ar Relative Abundance 2 Where is n = 2?

6. Py·(H 2 O) n [Py·(H 2 O) n ]¯ n = 2 n = 3 Rearrangement Coordinate Potential Energy Previous Explanation for Onset at n = 3 Desfrancois, et al. Electron. Spectrosc. 2000

7. Py·(H 2 O) 3 ¯ Electron Binding Energy (eV) Photoelectron Yield E 0.000.501.001.502.00 Velocity Map Imaging Photoelecton Spectrum · Peak at 1.53 eV implies valence electron · Breadth implies VDE >> AEA · Not resolved for structural determination

8. More Complicated Potential Energy Surface VDE

9. 8001200160020002400280032003600 [Py∙(H 2 O) n ]¯ Predissociation Yield n = 3 n = 4 Photon Energy (cm -1 ) n = 5 Photoelectrons Hydration Study

10. 8001200160020002400280032003600 PyH∙(H 2 O) n-1 ∙OH¯ × 30 Calculated Intensity / Predissociation Yield Photon Energy (cm -1 ) n = 5 × 10× 3 Perfect agreement??? CH DD AD DD Bend Py AAD OH¯ bound 2 nd Shell AD free NH M06-2X/6-31+G** AAD AD Experiment and Theory

11. Comparison to Model Compounds PyH∙(H 2 O) 4 ∙OH¯ Relative Intensity Prediss. Yield PyH ∙ Py Photon Energy (cm -1 ) 10001200140016001800 HOH bending (In a solid p-H 2 matrix) (FTIR of vapor) Golec, et al. J. Phys. Chem. A 2013 NIST chemistry webbook

12. Acknowledgements Johnson Lab (Yale) Zwier Lab (Purdue) McLuckey Lab (Purdue) Theory: Ken Jordan (U Pitt), Nathan Hammer (Ole Miss) Funding Agencies: DOE

13. Extra Slides

14. Electron Kinetic Energy (eV) 1.01.52.02.5 NO ¯ Photoelectron Spectrum Continuum A-A- A hν pump Photoelectron Spectroscopy hν pump = EBE + EKE EBE EKE

15. Ion Packet r hν pump E e-e- r NO ¯ Image Velocity Map Imaging (VMI) μ -Metal Repeller (-) Ground Extractor (+) Flight Tube MCP Front MCP Back Phosphor CCD Camera

16. More Complicated Potential Energy Surface PyH·(H 2 O) 2 ·OH¯ Rearrangement Coordinate Potential Energy Py·(H 2 O) 3 v = 0 v = 1 VDE Py ¯ ·(H 2 O) 3 AEA X VDE = 1.66 eV (B3LYP/aug-cc-pVTZ ) VDE = 0.75 eV

17. Multiple Isomers? AD1 AD2 DD 4.v 93.6 meV 4.ii 22.4 meV DD AD1 AD2 AD1 AD2 DD 4.iv 64.7 meV AD1 AD2 DD 4.i 0.00 meV 4.iii 60.1 meV D1 D2 D3

18. IR-IR Double Resonance Ion Optics 2m Flight Tube Wiley- McLaren TOF Reacceleration Pulsed Valve Electron Gun MCP Detector Nd:YAG OPO/OPA Reflectron Nd:YAG OPO/OPA Laser 1:Laser 2: Photofragment signal from laser 2 dips when laser 1 is on resonance with blue isomer v = 0 v = 1 Scanning Fixed on Resonace

19. AD1 AD2 DD 3450350035503600365037003750 Photon Energy (cm -1 ) Probe * * D1 D2 D3 / Hole-burn Depletion Predissociation Yield Calc. Intensity