Low temperature HD+ortho-/para-H2inelastic scattering of astrophysical interest

Sultanov, Renat A.; Guster, Dennis; Adhikari, Sadhan K.

doi:10.1088/0953-4075/49/1/015203

Cited by 12 publications

(7 citation statements)

References 48 publications

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“…For the initial HD molecular state prepared by V-SARP, we find an integral cross section of ~42 Å 2 , whereas for the state prepared by H-SARP, it is reduced by a factor of 3 to ~14 Å 2 . Our estimated cross section seems to agree with a prior theoretical prediction (30) within an order of magnitude, suggesting again the presence of a van der Waals resonance as described in that reference.…”

supporting

confidence: 91%

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Quantum control of molecular collisions at 1 kelvin

Perreault

Mukherjee

Zare

2017

Science

154

177

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Measurement of vector correlations in molecular scattering is an indispensable tool for mapping out interaction potentials. In a coexpanded supersonic beam, we have studied the rotationally inelastic process wherein deuterium hydride (HD) ( = 1, = 2) collides with molecular deuterium (D) to form HD ( = 1, = 1), where and are the vibrational and rotational quantum numbers, respectively. HD ( = 1, = 2) was prepared by Stark-induced adiabatic Raman passage, with its bond axis aligned preferentially parallel or perpendicular to the lab-fixed relative velocity. The coexpansion brought the collision temperature down to 1 kelvin, restricting scattering to s and p partial waves. Scattering angular distributions showed a dramatic stereodynamic preference (~3:1) for perpendicular versus parallel alignment. The four-vector correlation measured between the initial and final velocities and the initial and final rotational angular momentum vectors of HD provides insight into the strong anisotropic forces present in the collision process.

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supporting

confidence: 91%

“…A large number of theoretical studies on inelastic collisions involving hydrogen molecules have been done in the past, which systematically point to the presence of resonances near 1 K (27)(28)(29)(30). These resonances suggest that strong van der Waals forces may govern these collisions, but no experiments have yet tested any of these predictions.…”

mentioning

confidence: 99%

Quantum control of molecular collisions at 1 kelvin

Perreault

Mukherjee

Zare

2017

Science

154

177

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“…Then, collisions between HD and these projectiles have been the object of numerous studies . For HD–He collisions, both experiments and computational works are available since the 1970s − and, more recently, they have been studied in the astrophysical context. , For HD–H 2 , new calculations have been recently published in the cold temperature regime, − and seminal works can be found earlier. , …”

Section: Introductionmentioning

confidence: 99%

Rotational Excitation of HD by Hydrogen Revisited

et al. 2018

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The HD molecules are key species for the cooling of pristine gas at temperatures below 100 K. They are also known to be key tracers of H2 in protoplanetary disks and thus, they can be used as a measure of protoplanetary disks mass. Accurate modeling of the cooling mechanism and of HD abundance in astrophysical media requires a proper modeling for its excitation by both radiative and collisional processes. Here, we report quantum time-independent calculations of collisional rate coefficients for the rotational excitation of HD by H for temperatures ranging from 10 to 1000 K. The reactive and hydrogen exchange channels are taken into account in the scattering calculations. New exact quantum results are compared to previous calculations performed neglecting reactive and exchange channels. We found that for temperatures higher than ∼300 K, the impact of these channels on the rate coefficients cannot be neglected. Such results suggest that the new HD–H collisional data have to be used for properly modeling HD cooling function and HD abundance in all the astrophysical environments where HD plays a role, e.g. in photon-dominated regions, protoplanetary disks, early Universe chemistry, and primordial star forming regions.

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“…In the early Universe, atomic hydrogen is the dominant species. Notably because of their high astrophysical interest, numerous ex-perimental and theoretical studies of HD in collision with helium and molecular hydrogen have been carried out over the past fifty years (Itikawa & Takayanagi 1972;Itikawa 1974;Chu 1975;Gentry & Giese 1977;Roueff & Zeippen 1999;Flower & Roueff 1999a;Nolte et al 2012;Sultanov et al 2012Sultanov et al , 2016Croft et al 2018;Wan et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Collisional excitation of HD by H

Desrousseaux

Coppola

Lique

2022

Monthly Notices of the Royal Astronomical Society

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The HD molecule plays an important role in many astrophysical environments. Accurate modelling of the gas cooling induced by HD and its abundance in such media requires a proper modelling of its excitation by both radiative and collisional processes. Reliable state-to-state collisional rate coefficients in extended temperature regimes are then essential to allow for the description of different astrophysical environments where deviations from local thermodynamic equilibrium regime can occur. Here, we report exact quantum time-independent reactive scattering calculations for the ro-vibrational excitation of HD by H. Rate coefficients are computed for temperatures up to 5000 K and transitions between all ro-vibrational states with internal energies up to 14,000 cm−1. Previous results neglecting reactive and exchange channels of the colliding system are compared to the new ones and significant differences are found. The present work represent a big step in the complete description of the HD–H collisional system, in terms of rovibrational states considered, temperature range explored and accuracy. Hence, we recommend the use of the new HD–H collisional data presented here to accurately model the astrophysical environments where HD plays a role.

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Low temperature HD+ortho-/para-H₂inelastic scattering of astrophysical interest

Cited by 12 publications

References 48 publications

Quantum control of molecular collisions at 1 kelvin

Quantum control of molecular collisions at 1 kelvin

Rotational Excitation of HD by Hydrogen Revisited

Collisional excitation of HD by H

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