Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Canadian Journal of Chemistry

Collisions and reactions of ultracold molecules

William C. Stwalley

Published Jun 1, 2004• 33 citations
Publisher

Abstract

It is argued that collision dynamics of atoms and molecules at ultracold temperatures (below 1 mK) are not readily predictable from knowledge of collision dynamics above 100 K. In the case of elastic collisions, it is well known that the collision cross section is constant as T → 0 K but mass and symmetry effects are dramatic. The cases of inelastic and reactive collisions are less studied, but a T–1/2 dependence of the cross section as T → 0 K is expected. It seems that extrapolations of high-temperature inelastic and reactive behavior normally greatly underestimate ultracold-temperature rates. The prospects for experimental observation of ultracold collision dynamics are rapidly improving.Key words: ultracold molecules, collisions, reactions, hydrogen, scattering length.

DOI
10.1139/v04-035

Related papers

Universal Rate Constants for Reactive Collisions of Ultracold Molecules

Zbigniew Idziaszek, Paul S. Julienne

A simple quantum-defect model gives analytic expressions for the complex scattering length and threshold collision rates of ultracold molecules. If the probability of reaction in the short-range part of the collision is high, the model gives universal rate constants for s- and p-wave collisions that are independent of short-range dynamics. This model explains the magnitudes of the recently measured rate constants for collisions of two ultracold 40K87Rb molecules, or an ultracold 40K atom with the 40K87Rb molecule [S. Ospelkaus et al., Science 327, 853 (2010).

arXiv:0912.0370•Physical Review Letters•Mar 18, 2010•223 citations

Molecular collisions in ultracold atomic gases

Jeremy M. Hutson, Pavel Soldán

It has recently become possible to form molecules in ultracold gases of trapped alkali metal atoms. Once formed, the molecules may undergo elastic, inelastic and reactive collisions. Inelastic and reactive collisions are particularly important because they release kinetic energy and eject atoms and molecules from the trap. The theory needed to handle such collisions is presented and recent quantum dynamics calculations on ultracold atom–diatom collisions of spin-polarized Li + Li2, Na + Na2 and K + K2 are described. All these systems have potential energy surfaces on which barrierless atom exchange reactions can occur, and both inelastic and reactive rates are very fast (typically k inel > 10-10 cm3 s−1 in the Wigner regime).

arXiv:physics/0610219•International Reviews in Physical Chemistry•Jan 1, 2007•87 citations

Ultracold molecules and ultracold chemistry

Martin T. Bell, T. P. Softley

The recent development of a range of new methods for producing samples of gas-phase molecules that are translationally cold ( K) or ultracold ( mK) is driving efforts to study reactive and inelastic collisional processes in these temperature regimes. In this review article the new methods for cold/ultracold molecule production are reviewed in the context of their potential or current use in collisional studies and progress in the application of these methods is highlighted. In these sub-Kelvin temperature ranges, where the de Broglie wavelength is long compared with molecular dimensions, quantum effects may play a crucial role in the collision dynamics. Reactions with no potential energy barrier are of greatest importance, and this review article summarizes some of the principal theoretical approaches to understanding quantum effects in these barrierless processes.

Molecular Physics•Jan 20, 2009•277 citations

Inelastic Collisions and Chemical Reactions of Molecules at Ultracold Temperatures

Goulven Quéméner, N. Balakrishnan, A. Dalgarno

This paper summarizes the recent theoretical works on inelastic collisions and chemical reactions at cold and ultracold temperatures involving neutral or ionic systems of atoms and molecules. Tables of zero-temperature rate constants of various molecules are provided.

•Jun 25, 2009•3 citations

Feshbach resonances in ultracold atomic and molecular collisions: threshold behaviour and suppression of poles in scattering lengths

Jeremy M. Hutson

In the absence of inelastic scattering, Feshbach resonances produce poles in scattering lengths and very large peaks in elastic cross-sections. However, inelastic scattering removes the poles. Whenever the resonant state is coupled comparably to the elastic and inelastic channels, the scattering length exhibits only a small oscillation and peaks in cross-sections are significantly suppressed. A resonant scattering length is defined to characterize the amplitude of the oscillation, and is shown to be small for many collisions of ultracold molecules. The results suggest that cross-sections for some ultracold collision processes will be much less sensitive to details of the potential than has been expected.

arXiv:physics/0610210•New Journal of Physics•May 24, 2007•129 citations

Inelastic Collisions and Chemical Reactions of Molecules at Ultracold Temperatures

Goulven Quéméner, N. Balakrishnan, A. Dalgarno

This paper summarizes the recent theoretical works on inelastic collisions and chemical reactions at cold and ultracold temperatures involving neutral or ionic systems of atoms and molecules. Tables of zero-temperature rate constants of various molecules are provided.

arXiv:1001.1713•Jan 11, 2010•0 citations
It is argued that collision dynamics of atoms and molecules at ultracold temperatures (below 1 mK) are not readily predictable from knowledge of collision dynamics above 100 K. In the case of elastic collisions, it is well known that the collision cross section is constant as T → 0 K but mass and symmetry effects are dramatic. The cases of inelastic and reactive collisions are less studied, but a T–1/2 dependence of the cross section as T → 0 K is expected. It seems that extrapolations of high-temperature inelastic and reactive behavior normally greatly underestimate ultracold-temperature rates. The prospects for experimental observation of ultracold collision dynamics are rapidly improving.Key words: ultracold molecules, collisions, reactions, hydrogen, scattering length.
A simple quantum-defect model gives analytic expressions for the complex scattering length and threshold collision rates of ultracold molecules. If the probability of reaction in the short-range part of the collision is high, the model gives universal rate constants for s- and p-wave collisions that are independent of short-range dynamics. This model explains the magnitudes of the recently measured rate constants for collisions of two ultracold 40K87Rb molecules, or an ultracold 40K atom with the 40K87Rb molecule [S. Ospelkaus et al., Science 327, 853 (2010).
It has recently become possible to form molecules in ultracold gases of trapped alkali metal atoms. Once formed, the molecules may undergo elastic, inelastic and reactive collisions. Inelastic and reactive collisions are particularly important because they release kinetic energy and eject atoms and molecules from the trap. The theory needed to handle such collisions is presented and recent quantum dynamics calculations on ultracold atom–diatom collisions of spin-polarized Li + Li2, Na + Na2 and K + K2 are described. All these systems have potential energy surfaces on which barrierless atom exchange reactions can occur, and both inelastic and reactive rates are very fast (typically k inel > 10-10 cm3 s−1 in the Wigner regime).
The recent development of a range of new methods for producing samples of gas-phase molecules that are translationally cold ( K) or ultracold ( mK) is driving efforts to study reactive and inelastic collisional processes in these temperature regimes. In this review article the new methods for cold/ultracold molecule production are reviewed in the context of their potential or current use in collisional studies and progress in the application of these methods is highlighted. In these sub-Kelvin temperature ranges, where the de Broglie wavelength is long compared with molecular dimensions, quantum effects may play a crucial role in the collision dynamics. Reactions with no potential energy barrier are of greatest importance, and this review article summarizes some of the principal theoretical approaches to understanding quantum effects in these barrierless processes.
In the absence of inelastic scattering, Feshbach resonances produce poles in scattering lengths and very large peaks in elastic cross-sections. However, inelastic scattering removes the poles. Whenever the resonant state is coupled comparably to the elastic and inelastic channels, the scattering length exhibits only a small oscillation and peaks in cross-sections are significantly suppressed. A resonant scattering length is defined to characterize the amplitude of the oscillation, and is shown to be small for many collisions of ultracold molecules. The results suggest that cross-sections for some ultracold collision processes will be much less sensitive to details of the potential than has been expected.