1. Stark Study of the F 4     X 4  7/2 (1,0) band of FeH Jinhai Chen and Timothy C. Steimle Dept. of Chemistry& BioChem, Arizona State University, Tempe, AZ, 85287-1604 Jeremy J. Harrison and John M. Brown Physical and Theoretical Chemistry, University of Oxford Oxford, United Kingdom Supported by National Science Foundation – Exp. Phys. Chem. Published: JCP 124 184307/1-184307/7 (2006)

2. Motivation Determination of ground and excited state permanent electric dipole moments,   Insight into metal-H bonding from establishing trends: TiH (X 4  3/2 :2.455(3)D) a NiH( X 4  5/2 :2.4(1)D) b a) T.C. Steimle, J. E. Shirley, B. Simard, M. Vasseur, and P. Hackett, J. Chem. Phys. 95, 7179 (1991). b) J.A. Gray, S.F. Rice, and R. W. Field, J. Chem. Phys. 82, 4717 (1985).  Most fundamental electrostatic property; used for intensity  conc. conversion & other phenomena  Benchmark data for electronic structure calculations

3. Extensively studied in part due to its presence in stellar spectra History of Visible & NIR Spectroscopy of FeH

4. NIR-Fourier Transform emission: a)Phillips et al ApJ Supp. 65, 721 (1987). b)Dulick et al ApJ 594 651 (2003) c)Balfour et al J. Chem. Phys. 121, 7735 (2004) Laser Magnetic Resonance a)Pure rot; Ken Evenson group JCP 89 4446 (1988) b)Vib-rot: Evenson &Brown JCP (in press) Visible Spectroscopy a) Numerous studies by John Brown’s group Conclusion: The energy levels of the F 4  & X 4  states can not be modeled using effective Hamiltonian (severe B-O breakdown)! Previous spectroscopic studies

5. The Challenges of NIR Stark Study of FeH 1.No previously known mol. beam generation technique. 2. Fluorescence detection inefficient (1,0) (0,0)

6. Pulse valve/ablation source & Mol. Beam Machine

7. Proton Mag. Hyperfine splitting (Not previously observed) } 35 MHz FWHM

8. High resolution P(4.5) Line X & F State  Doubling Calc

9. J-dependence of  -doubling in the (v=1) F 4  7/2 State  E LD =[  D J(J+1)](J 2 -0.25)(J 2 -2.25)(J 2 -6.25)(J+3.5)

10. Stark effect on the Q(3.5) Line-Parallel Polarization

11. Stark effect on Q(3.5) Line-Perpendicular Polarization

12. Modeling Stark Effect in J=3.5 levels of X 4  7/2 state Field-free Matrix Basis:  n  S  J  IFM F > with  =  3/2,  2 &  =  7/2 H Stark H Stark = -  E Numerical diagonalization  Eigenvalues &vectors Similar approach for Stark effect in F 4  7/2 state H ij =Term value

13. Results Obs. (v=1) F 4  7/2 1.29(3)D (v=0) X 4  7/2 2.63(3)D Calc A 2.43 D 2.59 D A:CASSCF-MRCPS(4) Tanaka et al JCP 115 4558 (2001) Calc B 0.329 D 1.899 D B:CASSCF/MRCI Z. Wang, T. Sears &J. Muckerman (in preparation) C:CASSCF/CI-NO iteration Chong et al JCP 85, 2850 (1986) Calc C  2.9 .2 D Calc E  3.77 D E: Pseudopotential Dolg et al JCP 86, 2123 (1987)

14. Rationalizing why  (X 4  ) >>  ( F 4  ) Two bonding mechanisms: i) Fe(3d 7 4s) + H(1s)   bond formation ii) Fe(3d 6 4s 2 )  4s/5p hybridization + H(1s)   bond + occupied 4s/5p hybrid Evidently Fe(3d 6 4s 2 ) is more important in the F 4  state.

15. Thanks to: Brookhaven group for providing Ab Initio predications You for your attendance ! Summary: 1) Generated the first molecular beam of FeH 2) Determined  in X 4  & F 4  states NSF- $