1. MOLECULAR BEAM OPTICAL ZEEMAN SPECTROSCOPY OF VANADIUM MONOXIDE, VO
TRUNG NGUYEN, RUOHAN ZHANG, TIMOTHY STEIMLE

2. Outline Motivation Experimental setups
High-resolution spectroscopy of B4Π - X4Σ-
Analysis of the high-resolution spectroscopy and Zeeman effect

3. Motivation Supporting spectroscopy for
Magnetic investigation using Magnetic Doppler Imaging (MDI)
Hot “Jupiter”
Cool stars
Brown dwarfs
Keenan et al (1952)
Désert et al (2008) VO
The ground and excited states
Zeeman g-factor for the ground and excited states

4. Vanadium oxide, VO Advantages: Near infrared spectra
Isotope
Abundance (%) I
50V
0.25 6
51V
99.75
7/2
Near infrared spectra
Magnetic dipole moment
A’4Φ
A4Π
B4Π
C4Σ-
D4Δ
X4Σ- VO
State
Configuration
X4Σ-
σb2πb4σ4s1δ3d2
A4Π, A’4Φ
σb2πb4σ4s1δ3d1π3d1
B4Π
σb2πb4δ3d2π3d1
C4Σ-
σb2πb4δ3d2σ*13d
D4Δ
σb2πb4σ4s1δ3d1σ*13d
Hübner, Olaf, Julius Hornung, and Hans-Jörg Himmel. The Journal of chemical physics 143.2 (2015):
E. Broclawik, T.J. Borowski, Chem. Phys. Lett., 339, 433 (2001) 

5. Relevant previous spectroscopic studies
There is a need for recording the optical Zeeman spectroscopy of B4Π X4Σ− (0,0)
X 4S- : Pure rotational spectra: Suenram et al (1991) and Flory et al (2007);
Spectroscopic parameters for X 4S-
B4Π: Huang et al (1991) (Merer’s group)
B4Π X4Σ− (1, 0): Cheung et al (1994) (Merer’s group)
B4Π X4Σ− (0,0): Adam et al (1995)
Combined analysis of microwave, laser-induced fluorescence and Fourier transform emission spectra
Hyperfine structures and spectroscopic parameters for B4Π
High temperature fluorescence
Buffer gas cooling experiment C4Σ- ‒ X 4S: Weistein et al. (1992) (Doyle’s group)
samples subjected to a magnetic field
The first molecular beam study on the optical Zeeman spectroscopy of B4Π X4Σ− (0,0)

6. Production of VO: Ablated V + Ar(95%)/N2O (5%)
11/27/2018
2. Experimental details
Ablation laser
Generation via laser ablation/supersonic expansion
Supersonic expansion
Pulsed valve (~600 psi)
0.25’’ V rod
Production of VO: Ablated V + Ar(95%)/N2O (5%)

7. High-resolution optical Zeeman spectroscopy
Electromagnetic coil
Optical Zeeman Spectroscopy
PMT
Gated photon counter
LIF
skimmer
Ablation laser
N2O
Single freq. tunable laser radiation
V rod
Pulse
valve
Well collimated
molecular beam
Rot.Temp.<20 K
The chemical intermediates studied in this work were prepared under supersonic jet conditions using a pulsed laser ablation technique. Two types of pulsed laser- based spectroscopy were used to record electronic spectra, namely laser-induced fluorescence (LIF), dispersed fluorescence (DF)

8. Field-free spectra of B4Π  X4Σ- transition ( = 1/2)
Q41
Observations
LIF signal
Predictions(Pgopher) at 20K

9. rR42(0.5) F’=2; F”=3
rQ41(0.5) F’=3; F”=3
Observations
Predictions
(Pgopher)
LIF signal

10. tQ41(2.5) F’=6; F”=6
uR41(1.5) F’=3; F”=2
Observations
Predictions
(Pgopher)
LIF signal

11. N Modelling the Spectra VO molecule: S = 3/2, L = 0
Effective Hamiltonian for the ground state X4Σ- N
J+I=F F1 F2 F3 F4
N+S=J
Ziurys et al (2007)
VO molecule:
S = 3/2, L = 0
Hund’s case (b) coupling S = J+ N
4 close fine structure components
I = 7/2
Apply Hund’s case (b) effective Hamiltonian
Heff = Hrot + Hss + Hmhf + HeqQ
Effective Hamiltonian for the excited state B4Π
Heff =Hso + Hrot + Hss + Hmhf + HeqQ
𝐻 𝐹𝑖𝑛𝑒 𝑠𝑡𝑟𝑢𝑐 =𝐴 𝐿 𝑍 𝑆 𝑍 + 𝐴 𝐷 𝐿 𝑍 𝑆 𝑍 , 𝑅 𝜆 3 (3 𝑆 𝑍 2 − 𝑆 2 )+𝐵 𝑅 2 − 𝐷 𝑅 2 , 𝑅 𝛾 𝑅 ⋅ 𝑆
𝐻 𝑚ℎ𝑓 =[𝑎 𝐿 𝑍 +(𝑏+𝑐) 𝑆 𝑍 ] 𝐼 𝑍 =[𝑎 𝐿 𝑍 +( 𝑏 𝐹 𝑐) 𝑆 𝑍 ] 𝐼 𝑍 ≡ ℎ 𝛺 𝐼 𝑍
𝐻 𝑒𝑙𝑒𝑐𝑡𝑟𝑖𝑐 𝑞𝑢𝑎𝑑𝑟𝑢𝑝𝑙𝑒 = 𝑒𝑄 𝑞 𝐼 (2 𝐼 −1 (3 𝐼 𝑍 − 𝐼 2

12. Field-free fitting result and optimized parameters (in cm-1)
B4Π (in cm-1)
X4Σ- (in MHz)
Optimized
Adam et al
(1995)
Flory et al
(2007)
T1/2
(46)
(40) B
(31)
(52)
(14)
106D
-7.90(33)
0.6634(1) D
(39) q
(25)
(1) g
(39) gD
(75) gs
(81) l
(55) lD
(61)
102a
1.755(42)
1.093(14) bF
(66)
102d
(71)
(38) c
(19)
103eQq0
1.14(1.95)
1.5(66) cI
(51) bs
-0.660(14)
eqQ
-2.5(1.3)
RMS= cm-1

13. Zeeman low-J rQ41(0.5) and rR41(0.5) branch features of
B4Π1/2  X4Σ- (Perpendicular polarization)
Field Free
~ 100 Gauss
~ 100 Gauss
uR41(1.5)
Field Free
rQ41(0.5)

14. Zeeman low-J tQ41(2.5) branch feature of B4Π1/2  X4Σ- (Parallel polarization)
~ 100 Gauss
tQ41(2.5)
Field Free

15. Summary
The first cold molecular beam study on the optical Zeeman spectroscopy of B4Π  X4Σ− (0,0) was conducted
The field-free and optical Zeeman spectra have been recorded and are being analyzed
The determined field-free parameters are physically “unrealistic”
Alternative models are being pursuited
Spectra are being measured

16. Thank you for your attention