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

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

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

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): 024309. E. Broclawik, T.J. Borowski, Chem. Phys. Lett., 339, 433 (2001) 

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)

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%)

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)

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

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

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

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 2 𝐿 𝑍 𝑆 𝑍 , 𝑅 2 + + 2𝜆 3 (3 𝑆 𝑍 2 − 𝑆 2 )+𝐵 𝑅 2 − 𝐷 2 𝑅 2 , 𝑅 2 + +𝛾 𝑅 ⋅ 𝑆 𝐻 𝑚ℎ𝑓 =[𝑎 𝐿 𝑍 +(𝑏+𝑐) 𝑆 𝑍 ] 𝐼 𝑍 =[𝑎 𝐿 𝑍 +( 𝑏 𝐹 + 2 3 𝑐) 𝑆 𝑍 ] 𝐼 𝑍 ≡ ℎ 𝛺 𝐼 𝑍 𝐻 𝑒𝑙𝑒𝑐𝑡𝑟𝑖𝑐 𝑞𝑢𝑎𝑑𝑟𝑢𝑝𝑙𝑒 = 𝑒𝑄 𝑞 0 4 𝐼 (2 𝐼 −1 (3 𝐼 𝑍 − 𝐼 2

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 12571.492906(46) 12571.6885(40) B 0.510500(31) 0.512652(52) 16 379.618 6(14) 106D -7.90(33) 0.6634(1) D 0.019 363 8(39) q 0.041162(25) 0.0001733(1) g 672.168(39) gD 0.001 970(75) gs 0.220 4(81) l 60 881.03(55) lD 0.018 16(61) 102a 1.755(42) 1.093(14) bF 778.737(66) 102d -0.2962(71) -0.3591(38) c -129.84(19) 103eQq0 1.14(1.95) 1.5(66) cI 0.192 8(51) bs -0.660(14) eqQ -2.5(1.3) RMS= 0.00211 cm-1

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)

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

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

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