High-resolution optical spectroscopy with a buffer-gas-cooled beam of BaH molecules

Iwata, Geoffrey Z.; McNally, Rees; Zelevinsky, Tanya

doi:10.1103/physreva.96.022509

Cited by 46 publications

(33 citation statements)

References 30 publications

(51 reference statements)

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“…To perform measurements of the branching ratios for the relevant electronic transitions in BaH, we utilize two complementary techniques, both using our cryogenic BaH molecular beam [4]. The schematic of the experiment is shown in Fig.…”

Section: Franck-condon Factor Ratio Measurementsmentioning

confidence: 99%

Assignment of excited-state bond lengths using branching-ratio measurements: The B 2Σ+ state of BaH molecules

Moore

Lane²,

McNally

et al. 2019

Phys. Rev. A

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Vibrational branching ratios in the B 2 Σ + -X 2 Σ + and A 2 Π -X 2 Σ + optical-cycling transitions of BaH molecules are investigated using measurements and ab initio calculations. The experimental values are determined using fluorescence and absorption detection. The observed branching ratios have a very sensitive dependence on the difference in the equilibrium bond length between the excited and ground state, ∆re: a 1 pm (.5%) displacement can have a 25% effect on the branching ratios but only a 1% effect on the lifetime. The measurements are combined with theoretical calculations to reveal a preference for a particular set of published spectroscopic values for the B 2 Σ + state (∆r B−X e = +5.733 pm), while a larger bond-length difference (∆r B−X e = 6.3 − 6.7 pm) would match the branching-ratio data even better. By contrast, the observed branching ratio for the A 2 Π 3/2 -X 2 Σ + transition is in excellent agreement with both the ab initio result and the spectroscopically measured bond lengths. This shows that care must be taken when estimating branching ratios for molecular laser cooling candidates, as small errors in bond-length measurements can have outsize effects on the suitability for laser cooling. Additionally, our calculations agree more closely with experimental values of the B 2 Σ + state lifetime and spin-rotation constant, and revise the predicted lifetime of the H 2 ∆ state to 9.5 µs. II. SPECTROSCOPY BACKGROUNDThe optical and near-infrared spectra of BaH [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] are dominated by the three 5d-complex states that correlate to the 5d state of the Ba atom: B 2 Σ + , A 2 Π, and H 2 ∆. Since all three reach below the ground-state dissociation threshold, the only decay mechanisms are radiative. In addition, these three low-lying excited states possess spectroscopic parameters that closely resemble the X 2 Σ + ground state. The resulting diagonal Franck-Condon (FC) factors ensure absorption-emission cycles arXiv:1904.07326v2 [physics.atom-ph]

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Section: Franck-condon Factor Ratio Measurementsmentioning

confidence: 99%

Assignment of excited-state bond lengths using branching-ratio measurements: The B 2Σ+ state of BaH molecules

Moore

Lane²,

McNally

et al. 2019

Phys. Rev. A

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“…Magneto-optical traps (MOTs) for SrF [24], CaF [25,26] and YO [27] have been demonstrated and sub-Doppler temperatures have been reached [28]. The laser cooling of BaF [29][30][31], BaH [32], TlF [33], MgF [34], CaOH [35] and YbOH [36] is also being pursued. Magnetic [37,38] and optical [39,40] trapping of laser cooled molecules has been demonstrated and sympathetic [41,42] and evaporative cooling [43] is being explored.…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic characterization of aluminum monofluoride with relevance to laser cooling and trapping

et al. 2019

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Here we report on spectroscopic measurements of the aluminum monofluoride molecule (AlF) that are relevant to laser cooling and trapping experiments. We measure the detailed energy level structure of AlF in the X 1 Σ + electronic ground state, in the A 1 Π state, and in the metastable a 3 Π state. We determine the rotational, vibrational and electronic branching ratios from the A 1 Π state. We also study how the rotational levels split and shift in external electric and magnetic fields. We find that AlF is an excellent candidate for laser cooling on any Q-line of the A 1 Π -X 1 Σ + transition and for trapping at high densities.The energy levels in the X 1 Σ + , v = 0 state and within each Ω-manifold in the a 3 Π, v = 0 state are determined with a relative accuracy of a few kHz, using laser-radio-frequency multiple resonance and ionization detection schemes in a jet-cooled, pulsed molecular beam. To determine the hyperfine and Λ-doubling parameters we measure transitions throughout the 0.1 MHz -66 GHz range, between rotational levels in the X 1 Σ + , v = 0 state and between rotational and Λ-doublet levels in all three spin-orbit manifolds of the a 3 Π, v = 0 state. We measure the hyperfine splitting in the A 1 Π state using continuous wave (CW) laser-induced fluorescence spectroscopy of the A 1 Π, v = 0 ← X 1 Σ + , v = 0 band. The resolution is limited by the short radiative lifetime of the A 1 Π, v = 0 state, which we experimentally determine to be 1.90 ± 0.03 ns. The hyperfine mixing of the lowest rotational levels in the A 1 Π state causes a small loss from the the main laser cooling transition of 10 −5 . The off-diagonal vibrational branching from the A 1 Π, v = 0 state is measured to be (5.60 ± 0.02) × 10 −3 in good agreement with theoretical predictions. The strength of the spin-forbidden A 1 Π, v = 0 → a 3 Π, v = 0 transition is measured to be seven orders of magnitude lower than the strength of the A 1 Π, v = 0 → X 1 Σ + , v = 0 transition. We determine the electric dipole moments µ(X) = 1.515 ± 0.004 Debye, µ(a) = 1.780 ± 0.003 Debye and µ(A) = 1.45 ± 0.02 Debye in X 1 Σ + , v = 0, a 3 Π, v = 0 and A 1 Π, v = 0, respectively, by recording CW laser excitation spectra in electric fields up to 150 kV/cm.

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“…Although molecules have complex level structures that make them difficult to cool, there are a few that have almost closed electronic transitions suitable for laser cooling. So far, laser cooling has been demonstrated for SrF [52][53][54][55], YO [56], CaF [57][58][59], YbF [60], and SrOH [61], with several other species being pursued [62][63][64][65].…”

Section: Introductionmentioning

confidence: 99%

Controlling the ac Stark effect of RbCs with dc electric and magnetic fields

et al. 2020

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We investigate the effects of static electric and magnetic fields on the differential ac Stark shifts for microwave transitions in ultracold bosonic 87 Rb 133 Cs molecules, for light of wavelength λ = 1064 nm. Near this wavelength we observe unexpected two-photon transitions that may cause trap loss. We measure the ac Stark effect in external magnetic and electric fields, using microwave spectroscopy of the first rotational transition. We quantify the isotropic and anisotropic parts of the molecular polarizability at this wavelength. We demonstrate that a modest electric field can decouple the nuclear spins from the rotational angular momentum, greatly simplifying the ac Stark effect. We use this simplification to control the ac Stark shift using the polarization angle of the trapping laser.

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High-resolution optical spectroscopy with a buffer-gas-cooled beam of BaH molecules

Cited by 46 publications

References 30 publications

Assignment of excited-state bond lengths using branching-ratio measurements: The B 2Σ+ state of BaH molecules

Assignment of excited-state bond lengths using branching-ratio measurements: The B 2Σ+ state of BaH molecules

Spectroscopic characterization of aluminum monofluoride with relevance to laser cooling and trapping

Controlling the ac Stark effect of RbCs with dc electric and magnetic fields

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