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Explanation of efficient quenching of molecular ion vibrational motion by ultracold atoms.

Stoecklin T, Halvick P, Gannouni MA, Hochlaf M, Kotochigova S, Hudson ER - Nat Commun (2016)

Bottom Line: Here, we theoretically explain the recently observed exception to this rule: efficient vibrational cooling of BaCl(+) by a laser-cooled Ca buffer gas.We perform intense close-coupling calculations that agree with the experimental result, and use both quantum defect theory and a statistical capture model to provide an intuitive understanding of the system.This result establishes that, in contrast to the commonly held opinion, there exists a large class of systems that exhibit efficient vibrational cooling and therefore supports a new route to realize the long-sought opportunities offered by molecular structure.

View Article: PubMed Central - PubMed

Affiliation: Université de Bordeaux, Institut des Sciences Moléculaires, UMR 5255 CNRS, 33405 Talence, France.

ABSTRACT
Buffer gas cooling of molecules to cold and ultracold temperatures is a promising technique for realizing a host of scientific and technological opportunities. Unfortunately, experiments using cryogenic buffer gases have found that although the molecular motion and rotation are quickly cooled, the molecular vibration relaxes at impractically long timescales. Here, we theoretically explain the recently observed exception to this rule: efficient vibrational cooling of BaCl(+) by a laser-cooled Ca buffer gas. We perform intense close-coupling calculations that agree with the experimental result, and use both quantum defect theory and a statistical capture model to provide an intuitive understanding of the system. This result establishes that, in contrast to the commonly held opinion, there exists a large class of systems that exhibit efficient vibrational cooling and therefore supports a new route to realize the long-sought opportunities offered by molecular structure.

No MeSH data available.


Related in: MedlinePlus

Close-coupling and statistical capture comparison.Comparison between the close-coupling vibrational quenching rate coefficients  with the statistical capture rate  for five different colliding systems with the diatomic cation in the initial state (ν=1, j=0).
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f4: Close-coupling and statistical capture comparison.Comparison between the close-coupling vibrational quenching rate coefficients with the statistical capture rate for five different colliding systems with the diatomic cation in the initial state (ν=1, j=0).

Mentions: The validity of this model can be tested by comparing to known atom-ion quenching rates. Figure 4 shows a comparison of the statistical capture model to the quenching rate calculated from the Wigner threshold law for Ca-BaCl+ as well as several other species, which have been analysed by some of the authors9101112. Given the strong correlation with statistical capture model, we can create rules-of-thumb to aid future experiments realize efficient vibrational cooling. Namely, the vibrational quenching efficiency depends both on the strength of the long-range interaction potential, given by α, and on the density of states of the complex, given by De/ωe. The increase of the state density increases the lifetime of the complex and facilitates vibrational quenching.


Explanation of efficient quenching of molecular ion vibrational motion by ultracold atoms.

Stoecklin T, Halvick P, Gannouni MA, Hochlaf M, Kotochigova S, Hudson ER - Nat Commun (2016)

Close-coupling and statistical capture comparison.Comparison between the close-coupling vibrational quenching rate coefficients  with the statistical capture rate  for five different colliding systems with the diatomic cation in the initial state (ν=1, j=0).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4837476&req=5

f4: Close-coupling and statistical capture comparison.Comparison between the close-coupling vibrational quenching rate coefficients with the statistical capture rate for five different colliding systems with the diatomic cation in the initial state (ν=1, j=0).
Mentions: The validity of this model can be tested by comparing to known atom-ion quenching rates. Figure 4 shows a comparison of the statistical capture model to the quenching rate calculated from the Wigner threshold law for Ca-BaCl+ as well as several other species, which have been analysed by some of the authors9101112. Given the strong correlation with statistical capture model, we can create rules-of-thumb to aid future experiments realize efficient vibrational cooling. Namely, the vibrational quenching efficiency depends both on the strength of the long-range interaction potential, given by α, and on the density of states of the complex, given by De/ωe. The increase of the state density increases the lifetime of the complex and facilitates vibrational quenching.

Bottom Line: Here, we theoretically explain the recently observed exception to this rule: efficient vibrational cooling of BaCl(+) by a laser-cooled Ca buffer gas.We perform intense close-coupling calculations that agree with the experimental result, and use both quantum defect theory and a statistical capture model to provide an intuitive understanding of the system.This result establishes that, in contrast to the commonly held opinion, there exists a large class of systems that exhibit efficient vibrational cooling and therefore supports a new route to realize the long-sought opportunities offered by molecular structure.

View Article: PubMed Central - PubMed

Affiliation: Université de Bordeaux, Institut des Sciences Moléculaires, UMR 5255 CNRS, 33405 Talence, France.

ABSTRACT
Buffer gas cooling of molecules to cold and ultracold temperatures is a promising technique for realizing a host of scientific and technological opportunities. Unfortunately, experiments using cryogenic buffer gases have found that although the molecular motion and rotation are quickly cooled, the molecular vibration relaxes at impractically long timescales. Here, we theoretically explain the recently observed exception to this rule: efficient vibrational cooling of BaCl(+) by a laser-cooled Ca buffer gas. We perform intense close-coupling calculations that agree with the experimental result, and use both quantum defect theory and a statistical capture model to provide an intuitive understanding of the system. This result establishes that, in contrast to the commonly held opinion, there exists a large class of systems that exhibit efficient vibrational cooling and therefore supports a new route to realize the long-sought opportunities offered by molecular structure.

No MeSH data available.


Related in: MedlinePlus