1. ROTATIONALLY RESOLVED A 2 A 1 —X 2 E ELECTRONIC SPECTRA OF DEUTERATED ISOTOPOMERS OF THE METHOXY RADICAL Jinjun Liu, Ming-Wei Chen and Terry A. Miller Laser Spectroscopy Facility Department of Chemistry The Ohio State University 6/21/2007 ~ ~

2. Outline Talk II (RF02): CHD 2 O  Introduction: asymmetric deuteration  Theory: PES, effective Hamiltonian  Experimental setup and spectral result  Global fitting and molecular constants  Discussion: lifting of vibronic degeneracy  Summary and future work Talk II (RF02): CHD 2 O  Introduction: asymmetric deuteration  Theory: PES, effective Hamiltonian  Experimental setup and spectral result  Global fitting and molecular constants  Discussion: lifting of vibronic degeneracy  Summary and future work Talk I (RF01): CH 3 O

3. Asymmetric Deuteration  Introduces asymmetries in the PES  Reduces the symmetry of the normal vibrations without affecting the electronic symmetry properties  Helpful in the investigation of systems that are subject to vibronic coupling (e.g., Jahn-Teller effect ) by “decoupling” the correlation between electronic and nuclear dynamics:  lifts the vibronic degeneracy through ZPE effects  reveals the geometry distortion in the case of dynamic Jahn-Teller distortion  decouples the Jahn-Teller effect and spin-orbit interaction  Reduces the permutational symmetry  Helpful in understanding the properties of molecules performing large-amplitude motions (tunneling/free rotation)  Introduces asymmetries in the PES  Reduces the symmetry of the normal vibrations without affecting the electronic symmetry properties  Helpful in the investigation of systems that are subject to vibronic coupling (e.g., Jahn-Teller effect ) by “decoupling” the correlation between electronic and nuclear dynamics:  lifts the vibronic degeneracy through ZPE effects  reveals the geometry distortion in the case of dynamic Jahn-Teller distortion  decouples the Jahn-Teller effect and spin-orbit interaction  Reduces the permutational symmetry  Helpful in understanding the properties of molecules performing large-amplitude motions (tunneling/free rotation)

4. Asymmetric Deuteration: A Chronicle  1964 : ESR of Jahn-Teller related molecules [1]  Benzene anion (C 6 H 5 D - ): different spectra after single deuteration  Cyclo-octatetraene anion (C 8 H 7 D - ): no difference  1964-: ESR of matrix-isolated molecules  1982 : Optical spectroscopy of benzene in gas phase [2]  Direct measurement of the splitting of the degenerate states  1993 : Rotationally resolved LIF spectra of asymmetrically deuterated cyclopentadienyl (C 5 H 4 D, C 5 HD 4 ) [3]  Two vibronic bands (ΔE~±9cm -1 ) showing the lifting of the vibronic degeneracy  Rotational analysis of the split states revealing different symmetry and geometry of the two split states  2007 : Rotationally resolved PFI-ZEKE spectra of asymmetrically deuterated methane cation (CH 3 D +, CHD 3 + ) [4]  Isotopic isomers  Tunneling-free pseudorotation structure  1964 : ESR of Jahn-Teller related molecules [1]  Benzene anion (C 6 H 5 D - ): different spectra after single deuteration  Cyclo-octatetraene anion (C 8 H 7 D - ): no difference  1964-: ESR of matrix-isolated molecules  1982 : Optical spectroscopy of benzene in gas phase [2]  Direct measurement of the splitting of the degenerate states  1993 : Rotationally resolved LIF spectra of asymmetrically deuterated cyclopentadienyl (C 5 H 4 D, C 5 HD 4 ) [3]  Two vibronic bands (ΔE~±9cm -1 ) showing the lifting of the vibronic degeneracy  Rotational analysis of the split states revealing different symmetry and geometry of the two split states  2007 : Rotationally resolved PFI-ZEKE spectra of asymmetrically deuterated methane cation (CH 3 D +, CHD 3 + ) [4]  Isotopic isomers  Tunneling-free pseudorotation structure [1] A. Carrington, H. C. Longuet-Higgins, R. E. Moss, P. F. Todd, Mol. Phys. 9, 187 (1965) [2] B. Sharf, R. Vitenberg, B. Katz, Y. Band, J. Chem. Phys. 77, 2226 (1982) [3] L. Yu, D. W. Cullin, J. M. Williamson, T. A. Miller, J. Chem. Phys. 98, 2682 (1993) [4] H. J. Wörner and F. Merkt, J. Chem. Phys. 126, 154304 (2007)

5. Spectral Evidence of Lifting of Degeneracy LIF spectra of C 5 HD 4 (T~10K)  b-type  a-type

6. Lifting of Vibronic Degeneracy: a qualitative view C O H CsCs  A’ D D C O H CsCs  A” H H C 3v E D D

7. Lifting of Vibronic Degeneracy: a qualitative view C O H CsCs  |A”> state C O H CsCs  |A’> state C O H H CsCs  |A”> state C O CsCs  |A’> state H H D D

8. PES Normal JT (linear only) JT w/ SO (CH 3 O, CD 3 O) JT w/ SO & asym. deuteration (CH 2 DO, CHD 2 O)

9. PES Normal JT (linear only) JT w/ SO (CH 3 O, CD 3 O) JT w/ SO & asym. deuteration (CH 2 DO, CHD 2 O)

10. PES

11.  * A. V. Marenich, J. E. Boggsa, J. Chem. Phys. 122, 024308 (2005) Methoxy: when (dynamic) JT meets spin-orbit PES of X 2 E CH 3 O calculated (a) without and (b) with spin-orbit coupling for the normal vibrational mode v 6. * ~  -- RF01

12.  CH 3 O and CD 3 O: H EFF = H ROT + H COR + H SO + H SR + H JT + H CD Effective Hamiltonian: ground state  CH 2 DO and CHD 2 O:  Reduction of molecular symmetry (C 3v  C s ): H ROT, sym  H ROT, asym (B-C)/2 H COR, sym  H COR, asym θ H SO, sym  H SO, asym θ H SR, sym  H SR, asym ε ac, (ε bb -ε cc )/2  Removal of electronic degeneracy of the vibrationless level: + H Q or * D. Melnik, J. Liu, R. F. Curl, T. A. Miller, Mol. Phys. 105, 529 (2007) Δ E=E x (A ’ )-E y (A ” ) with  CH 2 DO  CHD 2 O Principal Axis Sys.  Internal Axis Sys.

13. Hamiltonian Elements, asym. terms  Lifting of vibronic degeneracy  Rotational  Coriolis  Spin-orbit  Spin-rotation *

14. Experimental Apparatus: LIF & SEP, hi & mod. res. CH 2 DONO/ CHD 2 ONO/ CD 3 ONO+ 1 st run Ne General Valve ControllerDG535 Pulse Generator XeF Excimer Laser XeCl Excimer Laser Ar + Laser Nd:YAG Laser Sirah Dye Laser Pulsed Dye Amplifier PC #1 PC #2 Nozzle Ring Laser T0T0 PMT SHG Frequency reading Photolysis Q-Switch Flash Lamp T 0 / GPIB T0T0 program synchronizing Lens

15. Experimental Simulation CHD 2 O, 3 2 0 Band

16. Experimental Simulation CHD 2 O, 3 2 0 Band

17. Accomplishment and Drawback  Global fitting of mw * and LIF (two rotationally resolved vibronic bands: ) spectra for CHD 2 O and CH 2 DO with standard deviation consistent with the experimental accuracy (<3MHz for mw and ~50MHz for LIF).  Vibronic degeneracy is lifted by the asymmetric deuteration  ΔE at the same order of magnitude as aξ e d (50-60cm -1 ) but different sign for CHD 2 O (+) and CH 2 DO (-)  Validity of the Hamiltonian  Combined fitting of LIF spectra (two bands) for CD 3 O.  Global fitting of mw * and LIF (two rotationally resolved vibronic bands: ) spectra for CHD 2 O and CH 2 DO with standard deviation consistent with the experimental accuracy (<3MHz for mw and ~50MHz for LIF).  Vibronic degeneracy is lifted by the asymmetric deuteration  ΔE at the same order of magnitude as aξ e d (50-60cm -1 ) but different sign for CHD 2 O (+) and CH 2 DO (-)  Validity of the Hamiltonian  Combined fitting of LIF spectra (two bands) for CD 3 O.  The upper component of the spin-orbit splitting (E 1/2 ) is accessible to neither of the experiment (mw and LIF, T~3K)  ΔE and aξ e d can not be well-determined for CHD 2 O and CH 2 DO due to the strong correlation between them ( ) and lack of information of the E 1/2 state  The upper component of the spin-orbit splitting (E 1/2 ) is accessible to neither of the experiment (mw and LIF, T~3K)  ΔE and aξ e d can not be well-determined for CHD 2 O and CH 2 DO due to the strong correlation between them ( ) and lack of information of the E 1/2 state * D. Melnik, V. Stakhursky, V. A. Lozovsky, T. A. Miller, C. B. Moore and F. C. De Lucia, WJ09, 59th International Symposium on Molecular Spectroscopy, 2004.

18. SEP experiment of CHD 2 O: pump transitions LIF

19. SEP experiment of CHD 2 O: dump transitions LIF SEP

20. SEP experiment of CHD 2 O: List of transitions *Too weak to be observed in the high-resolution SEP experiment. Pump transitionPump freq. Dump transitionDump freq. Obs.Cal.Cal.–Obs. |J’,N’,K’,p’> - |J”,K",Σ”,p”>(cm -1 )|J’,N’, K, p’> - |J, K, Σ, p>(cm -1 ) P a |1/2, 1, 1, -1> - |1/2, 0, 1/2, 1> |3/2, 1, 1, -1> - |1/2, 0, 1/2, 1> 32929.48 |3/2, 1, 1, -1> - |5/2, 2, -1/2, 1>32842.2258 32842.22510.0007 |1/2, 1, 1, -1> - |3/2, 2, -1/2, 1> 32845.490732845.49000.0007 |3/2, 1, 1, -1> - |3/2, 2, -1/2, 1> * |1/2, 1, 1, -1> - |3/2, 0, -1/2, 1> * |3/2, 1, 1, -1> - |3/2, 0, -1/2, 1> 32855.542932855.5472-0.0043 |1/2, 1, 1, -1> - |1/2, 0, -1/2, 1>32856.4708 32856.46900.0018 |3/2, 1, 1, -1> - |1/2, 0, -1/2, 1>32856.4806 32856.47780.0028 P b |1/2, 0, -1, 1> - |1/2, 0, 1/2, -1> 32928.47 |1/2, 0, -1, 1> - |3/2, 2, -1/2, -1>32845.4461 32845.4474-0.0013 |1/2, 0, -1, 1> - |3/2, 0, -1/2, -1> * |1/2, 0, -1, 1> - |1/2, 0, -1/2, -1> *

21. Global Fitting: mw, LIF & SEP A 3.1735 (14) (B+C)/2 0.79001 (24) Aζ t 0.997 (10) D k, D NK, D N,η e ζ t, η K ζ t 0 c aζ e d -53.44 (50) aDζ e d 0.0364 (38) ε aa -0.8686 (58) ε bc 0.130 (16) ε1ε1 0.0019 (16) ε 2a -0.0438 (45) ε 2b -0.0109 d h1h1 -0.00033 (36) h2h2 0.1212 (47) h 1K - 0.000591 (65) h 2K -0.00579 (40) h 1N, h 2N, h 4 0 c ΔEΔE -48.30 (55) (B-C)/20.02297 (24) θ tilt -1.94 (17) ε ab, ε ab_asym 0 c a. In cm -1, b. 2.5σ in parentheses c. fixed d.fixed to ε 2a *(B+C)/2A Rotational Spin-Orbit Coriolis Centrifugal Distortion Spin-Rotation Jahn-Teller Asym.

22. ΔE=E x (A’)-E y (A”): Principal Axis Sys.  Internal Axis Sys. Δ E=E b (A ’ )-E c (A ” ) = +45.09(468)cm -1 Δ E=E c (A ’ )-E b (A ” ) = -48.30(55)cm -1 Ab initio * : -47cm -1 * B3LYP/6-31+G(d,p) Freq=ReadIsotopes * Not scaled * C s geometry from: A. V. Marenich, J. E. Boggs, J. Mol. Structure, 780, 163 (2006) Ab initio * : 43cm -1 E b (A ” )>E c (A ’ ) E b (A ’ )>E c (A ” ) “mass dependent” CH 2 DO CHD 2 O θ<5 o

23. Spin-orbit splitting aξ e d CH 3 OCHD 2 OCH 2 DOCD 3 O 13 CH 3 O -61.43(9) [1] -53.44(50) [2] -82.86(4051) [2] -55.30(10) [3] -62.20(3) [4] [1] J. Liu, M. Chen, J. Yi, T. A. Miller, to be submitted [2] this work [3] T. Momose, private communication [4] T. Momose, Y. Endo, E. Hirota, T. Shida, J. Chem. Phys. 88, 5338 (1988) * 2.5σin the parentheses SO coupling Constant Electron angular momentum along z-axis a = -142.8 aξe = -134 Ham reduction /JT quenching factor

24. Summary and Future Work  New high-resolution SEP spectra of CHD 2 O, which connects the and states.  Correlation between now broken  Molecular constants for ground electronic state from the global fitting (mw, LIF, and SEP)  New high-resolution SEP spectra of CHD 2 O, which connects the and states.  Correlation between now broken  Molecular constants for ground electronic state from the global fitting (mw, LIF, and SEP)  SEP spectra of CH 2 DO and CD 3 O  Vibronic analysis involving dispersed fluorescence spectra of CHD 2 O  Quantitative analysis and comparison  SEP spectra of CH 2 DO and CD 3 O  Vibronic analysis involving dispersed fluorescence spectra of CHD 2 O  Quantitative analysis and comparison

25. Acknowledgement Miller Group GOES @ OSU Merkt Group XUV @ ETH Thank You! $NSF$ Robert Curl