stark study of the f 4 x 4 7/2 (1,0) band of feh jinhai chen and timothy c. steimle dept. of...
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Stark Study of the F4X47/2 (1,0) band of FeH
Jinhai Chen and Timothy C. SteimleDept. of Chemistry& BioChem, Arizona State University,
Tempe, AZ, 85287-1604
Jeremy J. Harrison and John M. BrownPhysical 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)
Motivation Determination of ground and excited state
permanent electric dipole moments,
Insight into metal-H bonding from establishing trends: TiH (X43/2:2.455(3)D)a NiH( X45/2:2.4(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
Extensively studied in part due to its presence in stellar spectra
FeH pref erent ially f ound in cool regions assoc. with sunspots.
FeH
}History of Visible & NIR Spectroscopy of FeH
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 F4 & X4 states can not be modeled using effective Hamiltonian (severe B-O breakdown)!
Previous spectroscopic studies
The Challenges of NIR Stark Study of FeH
1. No previously known mol. beam generation technique.
2. Fluorescence detection inefficient (1,0) (0,0)
Pulse valve/ablation source & Mol. Beam Machine
Field- f ree Observation high resolution Q(3.5) line
Proton Mag. Hyperfine splitting (Not previously observed)
}
35 MHz FWHM
Field- f ree ObservationHigh resolution P(4.5) Line
X & F State Doubling
Calc
J-dependence of -doubling in the (v=1) F47/2
State
ELD=[DJ(J+1)](J2-0.25)(J2-2.25)(J2-6.25)(J+3.5)
Stark effect on the Q(3.5) Line-Parallel Polarization
Stark effect on Q(3.5) Line-Perpendicular Polarization
Modeling Stark Effect in J=3.5 levels of X47/2 state
Field-free Matrix
Basis: nSJIFMF> with =3/2, 2 & = 7/2
HStark
HStark
HStark= -E
Numerical diagonalization Eigenvalues &vectorsSimilar approach for Stark effect in F47/2 state
Hij =Term value
Results
Obs.
(v=1) F47/2 1.29(3)D
(v=0) X47/2 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)
Rationalizing why (X4) >> (F4)
Two bonding mechanisms:
i) Fe(3d74s) + H(1s) bond formation
ii) Fe(3d64s2) 4s/5p hybridization+ H(1s) bond + occupied 4s/5p hybrid
Evidently Fe(3d64s2) is more important in the F4 state.
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 X4 & F4states
NSF- $