PFIZEKE spectroscopy of Be 2 O Ivan O

PFI-ZEKE spectroscopy of Be 2 O Ivan O. Antonov, Beau Barker, Michael C. Heaven Emory University, Department of Chemistry 1515 Dickey Drive, Atlanta GA 30322

What is known about Be 2 O ? L. Theard and D. Hildenbrand, J. Chem. Phys. 41(11), 8689 (1964) Heat of Formation of Be 2 O(g) by Mass Spectrometry C. Thompson and L. Andrews, J. Chem. Phys. 100(12), 8689 (1994) Recorded IR spectra in Ar matrix; nas = 1412. 4 cm-1 A. Boldyrev and J. Simons, J. Phys. Chem. 99, 15041 (1995) Ab initio study 2 P 2 P 2 S 2 S 1 S Be O 1 S Be-2 O+2 1 S Satisfies the “octet rule” so additional bonding through the O was unexpected

Be 2 O IP and vibrational frequencies Be 2 O+: 2Σ + ground state g 2Σ + first excited state at 3146 cm-1 u IP = 8. 119(5) e. V (exp. (PIE)) IP = 8. 195 (calc. (MRCI)) (Jeremy M. Merritt et al. , J. Phys. Chem. A, 113 (2009) 13300 -309)

Experiment PMT MCP Monochromator He with 0. 1% O 2 Ablation 1064 nm, 26 m. J Ablation laser Probe laser ZEKE field 1. 4 ~ 5. 5 V/cm Delay 1. 5 -2. 5 μs TOF mass-spec Probe laser(s) MCP Oscilloscope

1+1’ REMPI spectrum of Be 2 O++e- 30 2 10 3 1Σ + g

1+1’ REMPI spectrum of Be 2 O++e. R(1) 302103 vibrational band of Be 2 O 1Σ + g

2 V/cm PFI-ZEKE spectrum of Be 2 O =1. 5 s 0 V/cm Be 2 O++e- u ~ 144 cm-1 IP=8. 1183(1) e. V ωe=150. 5 cm-1 ω exe=3. 26 cm-1 v=0 v=1 v=2 1Σ + g

PFI-ZEKE spectrum of Be 2 O. Origin band 2 V/cm =1. 5 s 0 V/cm Be 2 O++e- N=3 N=1 N=5 B 0=0. 48 cm-1 r 0=1. 394 Å 2Σ + state by nuclear g spin symmetry N=7 1Σ + g

PFI-ZEKE spectrum of Be 2 O. v=1 bending band 4 V/cm =1. 5 s πu symmetry due to bending vibration B 1=0. 49 cm-1 Be 2 O++e- N=2 N=1 0 V/cm N=4 N=3 1Σ + g

PFI-ZEKE spectrum of Be 2 O. v=2 bending band 4 V/cm σ and δ components B 1=0. 50 cm-1 =1. 5 s 0 V/cm Be 2 O++e- N=3 N=1 N=5 N=4? N=7? 1Σ + g

PFI-ZEKE spectrum of Be 2 O. v=1 stretching band 4 V/cm N=3 N=5 G 1/2=1032 cm-1 B 1=0. 47 cm-1 =1. 5 s 0 V/cm Be 2 O++e- N=1 N=7 1Σ + g

Comparison of Be 2 O+ with neutral Be 2 O and theory r. Be. O n 1 , n 2 RCCSD(T) FV-CASSCF 1. 3912 1093. 9 (Σg+) 177. 6 ( u) 1. 3469; 1. 4753 1559. 25 (Σg+) 200. 28 ( u) IE (e. V) Be 2 O r. Be. O=1. 393(6) Å v 1=1039 cm-1 v 2=113 cm-1 4σg ≈ (1/√ 2)(Be 1(2 s)+Be 2(2 s)) 3σu ≈ (1/√ 2)(Be 1(2 s)-Be 2(2 s)) MRCISD(Q) DFT Exp. 1. 3931 1084. 40 (Σg+) 177. 42 ( u) 1. 394 ΔGv+1/2=1032 (Σg+) ωe=150. 5 ( u) Ωexe=3. 26 ( u) 8. 195 Be 2 O+ r. Be. O=1. 394(6) Å v 1≈1032 cm-1 v 2=150 cm-1 - nearly degenerate for Be 2 O essentially non-bonding 8. 119(5) e. V (PIE) 8. 1183(1) e. V ZEKE

Conclusions • ZEKE spectra of Be 2 O+ was obtained in the region 65500 -66500 cm-1 • IP = 8. 1183(1) e. V • Ground state 2Σg+ was confirmed • Bond length r 0=1. 394(6) Å • Vibrational frequencies v 1=1032 cm-1 and v 2=150. 5(3) cm-1 • Antisymmetric stretch and 1 st excited state were not observed in this work

Acknowledgements • Beau Barker • Group members: Keith Freel, Jiande Han, Humayun Kabir • Adviser Prof. Michael Heaven