Thermalisation of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"><mml:msubsup><mml:mi mathvariant="normal">C</mml:mi><mml:mn>2</mml:mn><mml:mo>−</mml:mo></mml:msubsup></mml:math> with noble gases in cold ion traps

Mant, Barry P.; Gianturco, F. A.; Wester, Roland; González-Sánchez, Lola; Yurtsever, E.

doi:10.1016/j.ijms.2020.116426

Cited by 8 publications

(17 citation statements)

References 48 publications

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“…As expected for a molecule with a strong bond, the contour plots of the V 0,0 (R, θ ) for each system are very similar to our earlier rigid-rotor (RR) PESs which were obtained without the vibrational averaging (and a different ab initio method for C 2 − -He) [49,50]. The minimum values of V 0,0 for each system occur at perpendicular geometries and are around −30 cm −1 at 4.5 Å for He, −110 cm −1 at 3.7 Å for Ne, and −490 cm −1 at 3.7 Å for Ar.…”

Section: C 2 − -He/ne/ar 3d Potential Energy Surfaces and Vibrationally Averaged Matrix Elementssupporting

confidence: 82%

“…Simulations of cooling rotational motion at typical helium pressures in ion traps showed thermalization to Boltzmann populations occurred within tenths of seconds. Very recently we have extended this work and also modeled the rotational cooling of C 2 − with neon and argon [50]. It was found that thermalization times of C 2 − with He and Ne were fairly similar but cooling was significantly faster with Ar.…”

Section: Laser Cooling Of Cmentioning

confidence: 92%

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Rovibrational quenching of C2− anions in collisions with He, Ne, and Ar atoms

et al. 2020

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The molecular anion C 2 − is currently of interest as a candidate for laser cooling due to its electronic structure and favorable branching ratios to the ground electronic and vibrational states. Helium has been proposed as a buffer gas to cool the molecule's internal motion. We calculate the cross sections and corresponding rates for rovibrational inelastic collisions of C 2 − with He, and also with Ne and Ar, on three-dimensional ab initio potential energy surfaces using quantum scattering theory. The rates for vibrational quenching with He and Ne are very small and are similar to those for small neutral molecules in collision with helium. The quenching rates for Ar, however, are far larger than those with the other noble gases, suggesting that this may be a more suitable gas for driving vibrational quenching in traps. The implications of these results for laser cooling of C 2 − are discussed.

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Section: C 2 − -He/ne/ar 3d Potential Energy Surfaces and Vibrationally Averaged Matrix Elementssupporting

confidence: 82%

Section: Laser Cooling Of Cmentioning

confidence: 92%

Rovibrational quenching of C2− anions in collisions with He, Ne, and Ar atoms

et al. 2020

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“…For both systems, the spherical term V 0 has the largest magnitude and is responsible for the overall attraction of both systems. As expected from the preceding discussion, the interaction of C − 2 with Ar gives a more attractive V 0 term but for H 2 this term is still relatively large in comparison to He and Ne shown in our earlier work [32]. In contrast, the V 2 term which is responsible for N = ±2 transitions during collisions, has a deeper minimum for C − 2 interacting with H 2 compared to Ar.…”

Section: − 2 /H 2 Ab Initio Calculations and Potential Energy Surfacesupporting

confidence: 70%

“…In a series of recent works, we have investigated various inelastic processes of noble gas atoms colliding with C − 2 to assess their usefulness as buffer gases for cold-ion trapping experiments. Our simulations showed that thermalisation times of the rotational states of C − 2 with noble gases decreased in the order helium > neon > argon, due to the increasing interaction energy with atomic size and with dipole polarisability which are then yielding larger rate coefficients [31,32]. We have also calculated the rate coefficients for vibrationally inelastic collisional quenching of the anion's ν = 2 and ν = 1 levels [33], a step which can be useful in laser cooling experiments.…”

Section: Introductionmentioning

confidence: 86%

“…A further comparison of the excitation and quenching cross-sections is provided in Figure 6 which present the rotationally inelastic cross-sections for C − 2 colliding with both p-H 2 (j = 0) and Ar. For the C − 2 /Ar system, the anion was treated as a pseudo-singlet ( 1 ) as the rate constants for the collisional cooling process were of primary interest [32]. This constraint simplifies the dynamics but does not greatly affect the accuracy of the calculations, as discussed previously in our earlier studies [31,63].…”

Section: Rotationally Inelastic Scattering Cross-sections and Rate Constantsmentioning

confidence: 99%

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Beyond the helium buffer: ¹²C⁻₂ rotational cooling in cold traps with H₂ as a partner gas: interaction forces and quantum dynamics

et al. 2021

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The scattering cross-sections and corresponding rate coefficients for rotationally inelastic collisions of 12 C − 2 ( 2 + g ) with H 2 ( 1 + g ) are presented over a broad range of cold-trap temperatures. They have been calculated using quantum scattering theory that employs a new ab initio potential energy surface. The rate coefficients for the inelastic processes in the anionic partner are used to model the thermalisation dynamics of 12 C − 2 using H 2 as a buffer gas, a trap partner which is found here to be far more efficient than the typical buffer gas He and even more so than when using Ar as a partner gas. The microscopic physics underlying these findings is discussed in some detail. We additionally compute and discuss 12 C − 2 quadrupole transitions by spontaneous emission and use the newly computed rates to show that the anion's rotational levels should be in local thermal equilibrium at typical interstellar conditions.

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BASECOL2023 scientific content

Dubernet,

Boursier,

Denis-Alpizar

et al. 2024

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The global context of making numerous data produced by researchers available requires collecting and organising the data, assigning meaningful metadata, and presenting the data in a meaningful and homogeneous way. The BASECOL database, which collects inelastic rate coefficients for application to the interstellar medium and to circumstellar and cometary atmospheres, meets those requirements. We aim to present the scientific content of the BASECOL2023 edition. While the previous versions relied on finding rate coefficients in the literature, the current version is populated with published results sent by the producers of data. The paper presents the database, the type of data that can be found, the type of metadata that are used, and the Virtual Atomic and Molecular Data Centre (VAMDC) standards that are used for the metadata. Finally, we present the different datasets species by species. As the BASECOL database, interconnected with the VAMDC e-infrastructure, uses the VAMDC standards, the collisional data can be extracted with tools using VAMDC standards and can be associated with spectroscopic data extracted from other VAMDC connected databases such as the Cologne database for molecular spectroscopy (CDMS), the jet propulsion laboratory molecular spectroscopy database (JPL), and the high-resolution transmission molecular absorption database (HITRAN).

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Thermalisation of C2− with noble gases in cold ion traps

Cited by 8 publications

References 48 publications

Rovibrational quenching of C2− anions in collisions with He, Ne, and Ar atoms

Rovibrational quenching of C2− anions in collisions with He, Ne, and Ar atoms

Beyond the helium buffer: ¹²C⁻₂ rotational cooling in cold traps with H₂ as a partner gas: interaction forces and quantum dynamics

BASECOL2023 scientific content

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Thermalisation of C2− with noble gases in cold ion traps

Cited by 8 publications

References 48 publications

Rovibrational quenching of C2− anions in collisions with He, Ne, and Ar atoms

Rovibrational quenching of C2− anions in collisions with He, Ne, and Ar atoms

Beyond the helium buffer: 12C−2 rotational cooling in cold traps with H2 as a partner gas: interaction forces and quantum dynamics

BASECOL2023 scientific content

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Beyond the helium buffer: ¹²C⁻₂ rotational cooling in cold traps with H₂ as a partner gas: interaction forces and quantum dynamics