HIGH RESOLUTION ROTATIONAL SPECTROSCOPY STUDY OF THE ZEEMAN EFFECT IN THE 2 Π 1/2 MOLECULE PbF Alex...
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Transcript of HIGH RESOLUTION ROTATIONAL SPECTROSCOPY STUDY OF THE ZEEMAN EFFECT IN THE 2 Π 1/2 MOLECULE PbF Alex...
HIGH RESOLUTION ROTATIONAL SPECTROSCOPY STUDY OF THE ZEEMAN EFFECT IN THE 2Π1/2 MOLECULE PbF
Alex Baum, Benjamin Murphy, Richard Mawhorter
Trevor J. Sears
T. Zh.Yang, P.M Rupasinghe, C.P. McRaven, N.E. Shafer-Ray
Lukas D. Alphei & Jens-Uwe Grabow
Pomona College, Claremont, CA
Brookhaven National Laboratory, Upton, NY
University of Oklahoma, Norman, OK
Leibniz Universität, Hannover, Germany
June 23, 2011
Facts about PbF
1. 1 unpaired electron
2. 2Π1/2 ground state
3. 4 isotopes- 204Pb19F, 206Pb19F, 207Pb19F, 208Pb19F- 19F I = ½- (even)Pb I = 0- 207Pb I = ½
4. e-EDM sensitive
Why do we like PbF?
•Very high internal electric field due to heavy nucleus
•Closely spaced states of opposite parity
•Small molecular g-factor (g≈0.05)
•Sensitivity to e-EDM in ground electronic state
Experimental Setup
Supersonic-jet Fourier transform microwave spectrometer located at Leibniz Universität Hannover
- 2-26.5 GHz range- Accurate to within 0.5 kHz
Laser Ablation- 20Hz infrared laser pulses ablate
lead into ions- Ions combine with fluorine
introduced as ~1% SF6 in Ne buffer gas
Experimental Setup
3 pairs of Helmholtz coils
Able to produce magnetic fields up to ~4 Gauss
From Jens-Uwe Grabow and Walther Caminati. Microwave spectroscopy: Experimental techniques. Frontiers of Molecular Spectroscopy, page p. 383. Elsevier, 2009
Zeeman Effect
2J+1 degeneracy of the spatial components of the rotational state with total angular momentum quantum number J lifted under application of a magnetic field
•Magnitude of splitting proportional to strength of magnetic field
•Selection rule ΔMJ = 0 or +/-1 depending on relative orientation of applied magnetic field to MW electric field
J
J
Example Zeeman Spectra
Perpendicular Magnetic Field: ∆M = ± 1
Parallel Magnetic Field: ∆M = 0
Parallel Magnetic Field: ∆M = 0
F = 3/2 → F = 5/2 transition: 207PbF22541.912MHz
Perpendicular Magnetic Field: ∆M = ± 1
F = 3/2 → F = 5/2 transition: 207PbF22541.912MHz
g-factor Definition
In general, the g-factor relates the magnetic moment of a particle to its associated angular momentum.
Examples include:
•Electron spin g-factor μS=geμBS/ħ where μB is the Bohr magneton.
•Nuclear g-factor• μN=gNμNI/ħ where μN is the nuclear magneton.
Zeeman Effect in 208Pb19F
Can approximate θ = 0 and μN/μB m∝ e/mp ≈ 1/1800 ≈ 0 with about 95% accuracy...
Goal: Determine G|| and G⊥
Zeeman Effect in 208Pb19F
With this approximation
Now, for an individual quantum state i
Conclusions
[2] K. I. Baklanov, A. N. Petrov, A. V. Titov, and M. G. Kozlov. Towards the electron EDM search. Theoretical study of PbF. ArXiv e-prints, January 2010.[19] M G Kozlov, V I Fomichev, Y Y Dmitriev, L N Labzovsky, and A V Titov. Calculation of the P- and T-odd spin-rotational hamiltonian of the PbF molecule. Journal of Physics B: Atomic and Molecular Physics, 20(19):4939, 1987.[25] P.M. Rupasinghe. Private Communication, 2010.
•This is the first experimental determination of the sign, and increases the precision in our knowledge of the value of the body fixed g-factors for PbF by more than an order of magnitude.
•This knowledge provides a strong foundation for the design of a robust and finely-tuned e-EDM experiment using PbF.
Acknowledgements
Special thanks to
•Dr. Richard Mawhorter•Dr. Jens-Uwe Grabow•Dr. Neil Shafer-Ray
Funded by a Sontag Fellowship from Pomona College