Time-resolved study of the A2Π state of CaH by laser spectroscopy

Liu, M.; Pauchard, Thomas; Sjödin, Marica; Launila, O.; Meulen, P. van der; Berg, Lars-Erik

doi:10.1016/j.jms.2009.06.004

Cited by 13 publications

(7 citation statements)

References 24 publications

(38 reference statements)

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“…FCFs and VBRs for the measured transitions of CaH. The experimental radiative lifetime for the A state was obtained from reference [49] and for the B state from reference [50]. The excited state vibrational quantum number is always ν = 0.…”

Section: Vibrational Branching Ratio Measurementmentioning

confidence: 99%

Direct laser cooling of calcium monohydride molecules

et al. 2022

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We demonstrate optical cycling and sub-Doppler laser cooling of a cryogenic buffer-gas beam of calcium monohydride (CaH) molecules. We measure vibrational branching ratios for laser cooling transitions for both excited electronic states A and B. We measure further that repeated photon scattering via the A←X transition is achievable at a rate of ∽ 1.6×106 photons/s and demonstrate the interaction-time limited scattering of ∽ 200 photons by repumping the largest vibrational decay channel. We also demonstrate a sub-Doppler cooling technique, namely the magnetically assisted Sisyphus effect, and use it to cool the transverse temperature of a molecular beam of CaH. Using a standing wave of light, we lower the molecular beam's transverse temperature from 12.2(1.2) mK to 5.7(1.1) mK. We compare these results to sub-Doppler forces modeled using optical Bloch equations and Monte Carlo simulations of the molecular beam trajectories. This work establishes a clear pathway for creating a magneto-optical trap (MOT) of CaH molecules. Such a MOT could serve as a starting point for production of ultracold hydrogen gas via dissociation of a trapped CaH cloud.

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Section: Vibrational Branching Ratio Measurementmentioning

confidence: 99%

Direct laser cooling of calcium monohydride molecules

et al. 2022

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“…To our knowledge there are no experimental absolute intensity measurements of CaH. However, a few lifetime measurements for a number of low‐lying vibrational states v = 0, 1, 2 of the X , A and B states were used to estimate the corresponding oscillator strengths or Einstein coefficients (Klynning et al ; Berg, Ekvall & Kelly ; Liu et al ). The permanent electric dipole moments of CaH were obtained experimentally for a few low electronic states using the Stark effect (Steimle, Chen & Gengler ; Chen & Steimle ).…”

Section: Introductionmentioning

confidence: 99%

ExoMol line lists - I. The rovibrational spectrum of BeH, MgH and CaH in theX ²Σ⁺state

Yadin¹,

Veness²,

Conti³

et al. 2012

Monthly Notices of the Royal Astronomical Society

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Accurate line lists for three molecules, BeH, MgH and CaH, in their ground electronic states are presented. These line lists are suitable for temperatures relevant to exoplanetary atmospheres and cool stars (up to 2000 K). A combination of empirical and ab initio methods is used. The rovibrational energy levels of BeH, MgH and CaH are computed using the programs level and dpotfit in conjunction with ‘spectroscopic’ potential energy curves (PECs). The PEC of BeH is taken from the literature, while the PECs of CaH and MgH are generated by fitting to the experimental transition energy levels. Both spin‐rotation interactions (except for BeH, for which it is negligible) and non‐adiabatic corrections are explicitly taken into account. Accurate line intensities are generated using newly computed ab initio dipole moment curves for each molecule using high levels of theory. Full line lists of rotation–vibration transitions for 9BeH, 24MgH, 25MgH, 26MgH and 40CaH are made available in an electronic form as supporting information to this paper and at http://www.exomol.com.

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“…Previous studies revealed the laser cooling features of AEMHs in the following aspects: (i) highly diagonal Franck–Condon factor (FCF) that describes the overlap of vibrational wave functions involved in the cooling optical transition ( A 2 Π 1/2 ← X 2 Σ + ); (ii) short radiative lifetime of the A 2 Π 1/2 state ( 9 BeH: 81 ns, 24 MgH: 43.6 ns, 40 CaH: 33.2 ns, 88 SrH: 33.8 ns, and 138 BaH: 136.5 ns , ), which corresponds to strong spontaneous radiation decay rate; (iii) no intervening electronic states (except BaH) in the X 2 Σ + ← A 2 Π 1/2 transition. Recently, BaH has been extensively examined by Zelevinsky et al both theoretically via ab initio calculations and experimentally via spectroscopic detection and direct laser cooling. − They obtained vibrational branching ratios for B 2 Σ + – X 2 Σ + and A 2 Π 1/2 – X 2 Σ + optical cycling transitions using fluorescence and absorption detection, confirming the A 2 Π 1/2 state as a superior choice for laser cooling rather than the B 2 Σ + state, based on which Zelevinsky et al adopted A 2 Π 1/2 ← X 2 Σ + as the optical cycling transition while repumping excited vibrational levels of the ground state through the B 2 Σ + state.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Investigation of Spectroscopic Properties of the Alkaline-Earth-Metal Monohydrides toward Laser Cooling and Magneto-Optical Trapping

et al. 2023

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Alkaline-earth-metal monohydrides MH (M = Be, Mg, Ca, Sr, Ba) have long been regarded as promising candidates toward laser cooling and trapping; however, their rich internal level structures that are amenable to magneto-optical trapping have not been completely explored. Here, we first systematically evaluated Franck−Condon factors of these alkaline-earth-metal monohydrides in the A 2 Π 1/2 ← X 2 Σ + transition, exploiting three respective methods (the Morse potential, the closed-form approximation, and the Rydberg−Klein−Rees method). The effective Hamiltonian matrix was introduced for MgH, CaH, SrH, and BaH individually in order to figure out their molecular hyperfine structures of X 2 Σ + , the transition wavelengths in the vacuum, and hyperfine branching ratios of A 2 Π 1/2 (J′ = 1/2,+) ← X 2 Σ + (N = 1,−), followed by possible sideband modulation proposals to address all hyperfine manifolds. Lastly, the Zeeman energy level structures and associated magnetic g factors of the ground state X 2 Σ + (N = 1,−) were also presented. Our theoretical results here not only shed more light on the molecular spectroscopy of alkaline-earth-metal monohydrides toward laser cooling and magneto-optical trapping but also can contribute to research in molecular collisions involving few-atom molecular systems, spectral analysis in astrophysics and astrochemistry, and even precision measurement of fundamental constants such as the quest for nonzero detection of electron's electric dipole moment.

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Time-resolved study of the A2Π state of CaH by laser spectroscopy

Cited by 13 publications

References 24 publications

Direct laser cooling of calcium monohydride molecules

Direct laser cooling of calcium monohydride molecules

ExoMol line lists - I. The rovibrational spectrum of BeH, MgH and CaH in theX ²Σ⁺state

Theoretical Investigation of Spectroscopic Properties of the Alkaline-Earth-Metal Monohydrides toward Laser Cooling and Magneto-Optical Trapping

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Time-resolved study of the A2Π state of CaH by laser spectroscopy

Cited by 13 publications

References 24 publications

Direct laser cooling of calcium monohydride molecules

Direct laser cooling of calcium monohydride molecules

ExoMol line lists - I. The rovibrational spectrum of BeH, MgH and CaH in theX 2Σ+state

Theoretical Investigation of Spectroscopic Properties of the Alkaline-Earth-Metal Monohydrides toward Laser Cooling and Magneto-Optical Trapping

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ExoMol line lists - I. The rovibrational spectrum of BeH, MgH and CaH in theX ²Σ⁺state