Spectroscopy in Traps: ISMS 2016 ISOLATING SITE-SPECIFIC SPECTRAL SIGNATURES OF INDIVIDUAL WATER MOLECULES IN H-BONDED NETWORKS Spectroscopy in Traps: ISMS 2016 Thank you Stephan!

Spectroscopy WITH Traps: ISMS 2016 ISOLATING SITE-SPECIFIC SPECTRAL SIGNATURES OF INDIVIDUAL WATER MOLECULES IN H-BONDED NETWORKS Spectroscopy WITH Traps: ISMS 2016 Thank you Stephan!

Tagging vibrational spectroscopy with three traps Paul trap L.S. Wang (R.M. Jordan) Ring trap (K. Asmis F.H.I & Leipzig) Linear octopole (Issendorf, Neumark, Etienne Garand (Wisconsin)

Recent advances in tagging: He below 5 K 2013: Gerlich Maier Roithova Schlemmer Photoexcite ions in situ in trap; Modulate He tag population detected after extraction a) 50K Heat Shield Mounted to Cryo Head Entrance Aperture Lens Sapphire Plate IR Laser Ions In Entrance Tube Lens RF Trap (B) Trap Entrance Aperature (A) Exit Entrance Aperature (C)

Our twist: Use as a tagging source for external mass-selected predissociation 50K Heat Shield Mounted to Cryo Head Entrance Aperture Lens Exit Aperture Lens Sapphire Plate Ions In Ions Out Entrance Tube Lens Exit Tube Lens RF Trap (B) Trap Entrance Aperature (A) Exit Entrance Aperature (C) b) Voltage A B C 2 V Trap 0 V Extract 2 V 0 V Chris Johnson Stony Brook -10 V

He tagging is hard: Need cryo octopole to achieve T<5K 1 2 3 4 5 6 SarGlyH+·Hen * SarGlyH (4.6 K) x5 SarGlyH (10.5 K) 145 150 155 160 165 170 175 180 185 190 195 m/z

Ar tag shift is 90 cm-1 on “free” OH in H+(H2O)3 νOHfree OHfree H7O3+·He 90 cm-1 νasym νsym b) M H7O3+·Ar 3500 3550 3600 3650 3700 3750 3800 Photon Energy, cm-1

Basic pattern of Zundel is same with He vs Ne, but lines narrow by a factor of two and slightly shift with He H5O2+ FWHM Width=11 cm-1 He Tag 3 cm-1 12 cm-1 8 cm-1 FWHM Width=20 cm-1 12 cm-1 10 cm-1 Ne Tag Ar Tag 800 1000 1200 1400 1600 1800 3400 3600 3800 Photon Energy, cm-1

How to get “structure” from vibrational spectra? Using isotopomer-selective spectroscopy to unravel embedded correlations in vibrational spectra Cs+∙(H2O)6

Calculated “harmonic” spectrum from “4+2” structure matches observed pattern. Can we challenge this assignment experimentally? Cs+∙(H2O)6 Xantheas & Johnson, J.C.P. 2016

Three types of water molecules: A, AD, AAD Use isotopomer-selective spectroscopy to unravel embedded correlations in vibrational spectra Three types of water molecules: A, AD, AAD Cs+∙(H2O)6 Cs A AD AAD Lisy’s “4+2 structure

Assignments arise from transitions on water molecules in distinct sites Xantheas & Johnson, Submitted

“4+2” structure best explains spectrum Cs+∙(H2O)6

Incorporation of intact H2O into Cs+(D2O)n 230 240 250 260 270 Relative Intensity (a.u.) Mass to Charge (amu/e) H2O exchange Cs+(D2O)n 5 6 7 Martin Beyer: No intra-molecular scrambling with hydrated alkali cations in clusters!

Isomer-selective Spectroscopy: MS3 IR2 vibrational hole burning hnpump hnprobe Nd:YAG pumped OPO/OPA 600 – 4500 cm-1 Nd:YAG pumped OPO/OPA 600 – 4500 cm-1 pulsed valve coaxial TOF reflectron reflectron ion beam drift tube ±1.5 keV 1 keV electron gun MCP ion detector MCP ion detector Argon-solvated Isomer I Argon-solvated Isomer II Isomer I or II fragment induced by pump laser Isomer II fragment induced by probe laser Signal Time of Flight, ms 17

MS-IR-MS-IR-MS pump fragment probe fragment pump fragment probe Argon-solvated Isomer 1 Argon-solvated Isomer 2 pump fragment Isomer 2 fragment induced by pump laser Isomer 2 fragment induced by probe laser Reflectron 1 (R1) Coaxial TOF (PA) Reflectron 2 (R2) probe fragment ±1.5 keV hnpump (P1) (scanned) hnprobe (P2) (fixed) pump fragment population probe fragment Signal population Time of Flight, ms

MS-IR-MS-IR-MS probe fragment pump fragment Argon-solvated Isomer 1 Isomer 2 fragment induced by pump laser Isomer 2 fragment induced by probe laser Reflectron 1 (R1) Coaxial TOF (PA) Reflectron 2 (R2) ±1.5 keV hnpump (P1) (scanned) hnprobe (P2) (fixed) population probe fragment Signal population Time of Flight, ms pump fragment

More isomers or spectroscopy? NO2‾ · H2O More isomers or spectroscopy? NO stretch Predissociation Yield oh bend is at 1595 H2O bend 1000 1400 1800 2800 3200 3600 Photon Energy, cm-1

A Application to NO2ˉ•H2O System Probe band A NO2ˉ•H2O •Ar Ion Dip Signal Probe band A A Predissociation Yield NO2ˉ•H2O •Ar Ion Dip Signal 2800 3000 3200 3400 3600 3800 Scanned pump photon Energy, cm-1

B Application to NO2ˉ•H2O System NO2ˉ•H2O •Ar Probe band B Ion Dip Signal B Predissociation Yield NO2ˉ•H2O •Ar Probe band B Ion Dip Signal 2800 3000 3200 3400 3600 3800 Scanned pump photon Energy, cm-1

A Only two isomers Application to NO2ˉ•H2O System Ion Dip Signal Predissociation Yield Only two isomers Ion Dip Signal 2800 3000 3200 3400 3600 3800 Scanned pump photon Energy, cm-1

Cs+∙(H2O)6 Xantheas & Johnson, J.C.P. 2016

All sites occupied equally! Single H2O displays almost same pattern as Cs+(H2O)6: No OH vibrational “excitons” OH stretching region Cs+(H2O)6 All sites occupied equally! D2 Predissociation Yield (a.u.) Cs+(D2O)5(H2O) 3350 3400 3450 3500 3550 3600 3650 3700 3750

Independent contributions of AD and A sites Probe 3718 Cs+(H2O)(D2O)5 IR2MS3 Dip Signal Conrad Wolke & Fabian Menges N2 Pred. Yield 3350 3400 3450 3500 3550 3600 3650 3700 3750 Photon Energy (cm-1)

Independent contributions of AD and A sites Probe 3718 Cs+(H2O)(D2O)5 IR2MS3 Dip Signal N2 Pred. Yield 3350 3400 3450 3500 3550 3600 3650 3700 3750 Photon Energy (cm-1)

Independent contributions of AD and A sites Probe Cs+(H2O)(D2O)5 IR2MS3 Dip Signal 3699 N2 Pred. Yield 3350 3400 3450 3500 3550 3600 3650 3700 3750 Photon Energy (cm-1)

Independent contributions of AD/AAD and A sites Probe 3718 Cs+(H2O)(D2O)5 IR2MS3 Dip Signal 3699 N2 Pred. Yield 3350 3400 3450 3500 3550 3600 3650 3700 3750 Photon Energy (cm-1)

Assignments are confirmed… And Lisy & crew were right Cs A AD AAD

Anne B. McCoy & Laura Dzugan (U. Washington) Thanks Theory Anne B. McCoy & Laura Dzugan (U. Washington) Ken Jordan (Pittsburgh) Sotiris Xantheas (PNNL) Shawn Kathmann Experiments Gary H. Weddle (Fairfield) Chris Johnson (Stony Brook) Joseph Fournier Conrad Wolke Knut Asmis, Nadja Heine, & Matias Fagiani (FHI & Leipzig) Mike Kamrath (EPFL) Olga Gorlova Patrick Kelleher Stephanie Craig Chinh Duong Joanna Denton Nan Yang Fabian Menges Joe DePalma

Gary Joanna Joe Olga Fabian & Chinh Patrick Conrad Stephanie