Transcript YbFZeeman_final.ppt

The 63rd International Symposium
on Molecular Spectroscopy, June 2008
Optical Zeeman Spectroscopy of
ytterbium monoflouride, YbF
Tongmei Ma & Timothy C. Steimle
Dept. Chem. & BioChem., Arizona State University, Tempe, AZ,USA
Colan Linton
Dept. Phys., University of New Brunswick, Frederiction, NB, Canada
John Brown & Cleone Butler
Physical & Theoretical Chemistry, Oxford University, Oxford, UK
Funded by: NSF-Exp.
The “why & how”
 Why? The heavy polar molecule, YbF, has been used
to set an upper limit on the electric-dipole moment
of the electron, de.
 Why? Precise knowledge of the magnetic g-factors
are needed for experimental measurement of de.
Hudson et al
Phys. Rev.
Lett. 2002
 How? Analysis of ultra-high resolution Optical
Zeeman spectrum.
Approach-Optical Zeeman Spectroscopy
1. Record at near natural linewidth the (0,0) A21/2X2S+ band of YbF field-free[a]. (Last year OSU)
2. Based upon results of “1”, record and analyze the
optical Zeeman effect in the low-J branch features
to obtain g-factors for both (v=0) A21/2 and X2S+
states of YbF.
Gated photon counter
Pulse
valve
Ablation laser
Reagent
&
Carrier
Metal target
PMT
skimmer
Well collimated
molecular beam
Rot.Temp.<10 K
[a]:
Electromagnet
Single freq. tunable laser
radiation
T.C. Steimle, T. Ma and C. Linton, J. Chem. Phys., 127, 234216
Electromagnet for Zeeman spectroscopy
(50G-1.2kG) (3kG-4kG)
NdFeB permanent
magnets
Mirror
-5-
Low-resolution LIF with Pulsed Dye laser
OP (4)
12
Next
frame
High-resolution LIF spectra of YbF: OP12(4)
Typical branch feature of (0,0) A21/2 - X2S+ band
ZEEMAN MEASUREMENT:
174YbF
174YbF
172YbF
176YbF
171YbF,G=0
172YbF
171YbF
G=1(a-h)
170YbF
G=2
173YbF
-6-
G=3
G=0
(i)
Field-free parameters for the v=0 of X2S+ and
A21/2 states of YbF[a]
[a]:
T.C. Steimle, T. Ma and C. Linton, J. Chem. Phys., 127, 234216
172YbF
(0,0) A21/2-X2S+ Optical Zeeman Transitions:
Selected for Zeeman
18104.8285 cm-1 & 18104.8347 cm-1
Zeeman Tuning of the OP12(2) transition for
(0,0)A21/2-X2S+ of 172YbF
Note: Significant tuning
(v=0)A21/2
J=0.5
II
I
Last slide
II
I
(v=0) X2S+
N=2
Mag. Field (G)
171YbF
OP
12(4):
(0,0) A21/2-X2S+ Optical Zeeman Transitions:
18103.2307 cm-1; OP12(3): 18104.1338 cm-1; OP12(2) 18105.0340 cm-1
Selected
for Zeeman
(next slide)
Zeeman Tuning of the OP12(2) transition for
(0,0)A21/2-X2S+ of 171YbF
(v=0)A21/2
J=0.5
(v=0) X2S+
N=2
Last slide
Mag. Field (G)
Field-free Hamiltonian:
X2S+:
Analysis
8×8 mat.rep.,Hund’s case (a)
BN2-DN4 +γN·S+bF(F)I·S+c(F)×(IzSz-1/3I·S)
A21/2:16×16 mat.rep.,Hund’s case (a)
T0,0+ALzSz+1/2AD[N2LzSz+LzSzN2]+BN2-DN4+
½(p+2q)(e-2iJ+S++e-2iJ-S-)+aIzLz+bFI·S+c(LzSz½I·S)+½d(e-2iI+S++e-2iI-S-)
Zeeman Hamiltonian
H Zee (eff .)  g L  B L z  g S  BSz 
gl μ B Sx Bx  S y B y   gl  B ei 2 S B  e i 2 S B 
A21/2
X2S
Four possible parameters; gL, gS,gl’ & gl
Three possible parameters; gS, gl’ & gl
Analysis-cont’
Truncate matrix to include lowest 6 rot. levels
X2S+
A2
8x8
N=0
48x48 mat.
rep.
8x8
N=1
8x8
N=2
16x16
J=1/2
96x96 mat.
rep.
16x16
J=3/2
16x16
J=5/2
8x8
N=3
16x16
J=7/2
8x8
N=4
16x16
J=9/2
8x8
N=5
Diagonalize  eigenvalues & eigenvectors
16x16
J=11/2
Experimental g-factors for YbF
State
gS
gL
gl
X2S+
2.0626(42)
A21/2
2.002(Fix) 1.1010(92) 0.0(Fix)
NA
gl’
0.0009(Fix)
0.0(Fix)
-0.7290(54)
Rms:10.3 MHz
> 2.002
> 1
gl (X2S+) fixed to Curl relationship
Large
Interpretation of g-factors for YbF
A 21/2 (v = 0) state:
Hund’s Case a limit
gL=1 & gS=2.00
DEZee= B BM J  ( g L   gS S /  J ( J  1)
DEZee(21/2 )=
0
Fitted gL (=1.101) >1
B 2 S
mixing
B 2 S
A 21/2
Fitted gL > 1
DE~3000cm-1
Further evidence of mixing:
gl’ (fitted)=-0.729
Obs.shift is significant
A 21/2
gl’ (Curl Relationship)=-0.801
X 2S(v = 0) state:
Fitted gS (=2.0646(64))
Significantly bigger than 2.002
Difficult to rationalize-thinking about this!
Concluding remarks
•The magnetic tuning of the low-J features in the A2-X2S+
transition has been precisely determined.
•The magnetic g-factors in the A21/2 state differ significantly
from those expected for a pure “ 2 “ state.
Thank You !