Funded by: DoE. Anh T. Le and Timothy C. Steimle Department of Chemistry and Biochemistry Arizona State University, Tempe,AZ * Varun Gupta, Corey A. Rice and John P. Maier Dept. of Chem. Univ. of Basel, Basel, Switzerland ‡ Sheng H. Lin and Chih-Kai Lin Department of Applied Chemistry National Chiao Tung University Hsinchu, Taiwan Visible spectrum of ZrO 2 The 66 th International Symposium on Molecular Spectroscopy, June 2011 ‡ Swiss National Science Foundation

Motivation Bonding in transition metal triatomic molecules. Structure: a) inserted b) T-shape c) superoxide ; M-OO Properties of excited states  photochemical precesses a) R and  b) vibrational frequencies c) electric dipole moments TiO 2 Publications: PCCP 11, 2649 (2009) ; PCCP (2010)

Previous studies (Exp.) Structure determination of the X 1 A 1 state.  = =108.1  R= Å Pure Rot X 1 A 1  1 = 887  40 cm -1 PES anion Electrostatic deflection  Bent Matrix isolation IR   1 = 884 cm -1  3 = 818 cm -1 Previous studies (Theory) X 1 A 1 state properties at RCCSD(T) X 1 A 1 state properties at CASSCF-CCSD(T) X 1 A 1 & a 3 B 2 state properties at TD-DFT & EOM-CCSD No predictions for the A 1 B 1 state.

Experimental method-ASU Well collimated molecular beam Rot.Temp.<20 K Pulsed dye laser PMT Box-car integrator Metal target Pulse valve skimmer Ablation laser Reagent & Carrier Zr Optimized for ZrO 2 Long box-car gate width Low ablation power Resolution 0.2 cm -1 Monochromator PMT

Experimental method-Basel Pulsed OPO laser Metal target Pulse valve skimmer Ablation laser Reagent & Carrier Zr Resolution 3 cm -1 F 2 (157 nm) laser MCP Ion Detector Mass-Selected REMPI

Observation REMPI spectra a LIF low resolution a.Department of Chemistry, University of Basel, Basel, Switzerland

ZrO 2 Dispersed Fluorescence Position of laser Progression on  Progression on  Progression of   on top of 1 Progression on   on top of 3 DLIF signal Wavelength (Å) cm cm cm -1

ZrO 2 -Dispersed Fluorescence Analysis 268 shifts from 13 bands fluorescence down to ground states 11 22 33  33  22 ExperimentCalculation Here 898(1) 287(2) 808(2) 9.86(52) 3.52(48) a) Zheng & Bowen J.Phys. A (2005) 109, Matrix a B3LYP b b) Chertihin & Andrews, J. Phys. Chem. (1995) 99, CCSD(T)/L b RCCSD(T) c c) Mok, Chau, Dyke & Lee, Chem. Phys. (2008) 458, TiO 2 968(7) 321(4) f rr =Stretch-stretch force constant Note:  1   3  f rr (X 1 A 1 )  0 X 1 A 1 Parameters:

Excitation Spectra Assignment (0,0,0) Analogy to TiO 2 : X 1 A 1 (0,0,0)  A 1 B 2 (v 1,v 2,v 3 ) TiO 2 A 1 B 2 state:  1 = 876(3),  2 = 184(1),  3 = 316(2) (0,1,0) (0,2,0) (0,3,0) (0,4,0) (0,0,1) (0,0,2) (0,0,3) (1,0,0) (2,0,0)

ZrO 2 -Excited State Analysis 40 spectral features in excitation spectra were assigned to 45 transitions 817(4) 149(4) 519(3) 3(2) 4.43(75) -8.50(78) 16307(8) i (3) 184(1) 316(2) Very Poor agreement 11 22 33  12  23 ExpCalculation a TiO 2  33 ee LanL2DZCASSCF a) Part of the current study S.H Lin & C-K. Lin Nat. Chaio Tung Univ. Note:  1 >>  3  f rr (A 1 B 2 ) is significant. ZrO 2 A 1 B 2 Parameters:

Spectral Simulation Exp.  i  R,  (X 1 A 1 ) and Exp.  i (A 1 B 2 ) and Guess R,  (A 1 B 2 ) GF Matrix Methods Assume f rr (X 1 A 1 )=0 f r  (A 1 B 2 )=0 Duschinsky transformation Transition wavenumber and FCF calculation Predicted Spectrum Observed Spectrum Visual comparison Improved R,  (A 1 B 2 ) Goal: use only experimental info to predict X 1 A 1 (0,0,0)  A 1 B 2 (v 1,v 2,v 3 ) spectrum

X 1 A 1 (0,0,0) A 1 B 2 ( 1, 2, 3 ) Two dimensional (2D) overlap integral for the a 1 modes. One dimensional (1D) overlap integral for the b 2 mode. Assuming displaced & distorted harmonic oscillators  Analytical expressions: “2D”: Chang. JCP 128, (2008) “1D”: Chang. JMolSpec 1232, 1021 (2005) Normal coordinates of lower state Normal coordinates of upper state Coordinate of lower state Coordinate of upper state Spectral Simulation (cont.)

Need to relate Q(X 1 A 1 ) to Q(A 1 B 2 ). Duschinsky transformation: Essential : Also, displacement of nuclei: Wilson’ “B” matrix: “G”  “B”  “B” T “L” symmetry coor., S  Normal coor., Q, transform Peter Chen’s review article (“Unimol Rxn Dyn” 1994): Spectral Simulation (cont.)

Intensity  Transition Moment Squared  Need A 1 B 2 / B 1 A 1 vibronic coupling: Wavefunction: A 1 B 2 ( 1, 2, odd )  X 1 A 1 (0,0,0) =0 (i.e. odd- 3 forbidden) Even- 3 transitions Odd- 3 transitions Adjustable parameter Vibronic coupling term Spectral Simulation (cont.)

(cm -1 ) Predicted No vibronic coupling Predicted with vibronic coupling Spectral Simulation (cont.) Observed Good!

The best structure and coupling for A 1 B 2 state: Vibronic coupling term  1.1 Bond length R e =1.828 Å bond angle =99º  6900 cm -1  21  cm -1 Too Big ! Spectral Simulation (cont.) Consistent with TiO 2 X1A1A1B2B1A1C1A2D1B2E1B1X1A1A1B2B1A1C1A2D1B2E1B1

Summary Large reduction in vibrational frequencies upon excitation (like TiO 2 ). Odd- 3 quanta transition observed (unlike TiO 2 ). First recording and analysis of electronic transitions for ZrO 2. Vibrational parameters benchmarks for future ab initio Simulation of excitation spectra in reasonable agreement with observation.

Anh Le Fang Wang Dr. Xiujuan Zhuang Sarah Frey Thank you !

A 1 B 2 (0, 2 ,0) A 1 B 2 (0, 2 ,1) A 1 B 2 (1, 2 ,0) Also a manifestation of vibronic coupling. Trends in lifetimes