Inelastic collisions of ultracold triplet Rb2 molecules in the rovibrational ground state

Drews, B.; Deiß, Markus; Jachymski, Krzysztof; Idziaszek, Zbigniew; Denschlag, Johannes Hecker

doi:10.1038/ncomms14854

Cited by 25 publications

(20 citation statements)

References 56 publications

(86 reference statements)

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“…This yields a loss rate of 3.0ð2Þ × 10 −10 cm 3 =s, which is larger than but close to the measured value. Our results are similar to the case in bialkali molecules, where loss rates of the same order of magnitude as universal loss were observed [2,4,5,7,13,32,33,35].…”

supporting

confidence: 90%

“…Experimentally, inelastic collisional (loss) rates have been measured in many bi-alkali molecules either in the 1 Σ ground state or the metastable 3 Σ state, including [4,13,33], and 87 Rb 2 [35]. For chemically reactive species, two molecules are likely lost when they reach distances much shorter than the van der Waals length l vdW ¼ ðmC 6 =ℏ 2 Þ 1=4 , where C 6 is the van der Waals coefficient and m is the molecular mass.…”

mentioning

confidence: 99%

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Observation of Collisions between Two Ultracold Ground-State CaF Molecules

et al. 2020

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We measure inelastic collisions between ultracold CaF molecules by combining two optical tweezers, each containing a single molecule. We observe collisions between 2 Σ CaF molecules in the absolute ground state jX; v ¼ 0; N ¼ 0; F ¼ 0i, and in excited hyperfine and rotational states. In the absolute ground state, we find a two-body loss rate of 1.4ð8Þ × 10 −10 cm 3 =s, which is below, but close to, the predicted universal loss rate.

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supporting

confidence: 90%

mentioning

confidence: 99%

Observation of Collisions between Two Ultracold Ground-State CaF Molecules

et al. 2020

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“…Using the state-of-the-art experimental methods described earlier in this Review, collisions have been studied in ensembles of gases at temperatures on the order of a few hundreds of nK in systems including KRb [137][138][139] , NaLi 140 , triplet Rb 2 141 , Li 2 142 , NaRb 143,144 , RbCs 81 , NaK + K 145 and NaK 146 . For all these systems of trapped ultracold molecules, fast collisional trap-loss rates have been observed.…”

Section: Reactions In the Ultracold Regime Below 1 Mkmentioning

confidence: 99%

Towards chemistry at absolute zero

Heazlewood¹,

Softley

2021

Nat Rev Chem

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The prospect of cooling matter down to temperatures that are close to the absolute zero raises intriguing questions about how chemical reactivity changes under these extreme conditions. Although some types of chemical reaction still occur at 1 µK, they can no longer adhere to the conventional picture of reactants passing over an activation energy barrier to become products. Indeed at ultracold temperatures, the system enters a fully quantum regime, and quantum mechanics replaces the classical picture of colliding particles. In this Review, we discuss recent experimental and theoretical developments that allow us to explore chemical reactions at temperatures that range from 10 K to 500 nK. Although the field is still in its infancy, exceptional control has already been demonstrated over reactivity at low temperatures.ultracold temperatures, the classical description of the collision of particles needs to be replaced with a quantum description and the picture of a ball rolling over a hill needs to be replaced by that of a wave propagating across a barrier.The quantum regime is a physical regime in which our basic understanding of how chemical processes happen, in terms of molecules bumping into each other and breaking and remaking bonds, needs to be challenged. Strictly speaking, the dynamical system of moving and colliding molecules needs to be described as a superposition of partial waves, the components of which represent the different angular momentum states associated with the relative motion of the colliding particles. As the temperature is lowered, the system moves towards a regime in which it can be described by just a few quantised collisional angular momentum states (and, ultimately, just a single state). We denote the collisions as 's-wave' or 'p-wave' collisions (known as the partial-wave description) to represent those with zero or one unit of collisional angular momentum, respectively. Furthermore, in the quantum regime the population of molecular quantum states is distributed over just a few rovibrational states and ultimately collapses to a single quantum state at the lowest temperatures (under conditions of thermal equilibrium). At low temperatures, quantum effects on the rate coefficient and other properties of the reaction, such as collision energy resonances, quantum reflection and geometric phase (described in detail in the 'Reactions in the ultracold regime' section), are most likely to be observable. This is in contrast to what we observe at room temperature, where we understand the overall rate of a process to be an average of the behaviours of individual collisions of molecules with vastly varying sets of quantum numbers and a distribution of energies.When the temperature reaches sub-µK, the translational wavelength typically exceeds the average separation of molecules in the sample, even for a low density gas, and ultimately the system may enter the regime of quantum degeneracy (for example, bosonic particles that form a Bose-Einstein condensate, in which all particles are in the same quan...

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“…The field of ultracold chemistry has been demonstrating an increasing level of control over internal and external states of atomic and molecular reactants 1 – 4 . However, even cold reactions have in general many possible final product states 5 – 15 and reaction channels are therefore hard to track individually 16 . Nevertheless, reactions do exist where essentially only a single reaction channel is participating, such as atom-Feshbach molecule exchange reactions in Bose–Bose 17 and Bose–Fermi 18 mixtures, and three-body recombination A + A + B → AB + A in a Fermi–Fermi mixture 19 .…”

Section: Introductionmentioning

confidence: 99%

Reaction kinetics of ultracold molecule-molecule collisions

Hoffmann¹,

Paintner²,

Limmer³

et al. 2018

Nat Commun

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Studying chemical reactions on a state-to-state level tests and improves our fundamental understanding of chemical processes. For such investigations it is convenient to make use of ultracold atomic and molecular reactants as they can be prepared in well defined internal and external quantum states. Here, we investigate a single-channel reaction of two Li2-Feshbach molecules where one of the molecules dissociates into two atoms 2AB ⇒ AB + A + B. The process is a prototype for a class of four-body collisions where two reactants produce three product particles. We measure the collisional dissociation rate constant of this process as a function of collision energy/temperature and scattering length. We confirm an Arrhenius-law dependence on the collision energy, an a4 power-law dependence on the scattering length a and determine a universal four body reaction constant.

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Inelastic collisions of ultracold triplet Rb2 molecules in the rovibrational ground state

Cited by 25 publications

References 56 publications

Observation of Collisions between Two Ultracold Ground-State CaF Molecules

Observation of Collisions between Two Ultracold Ground-State CaF Molecules

Towards chemistry at absolute zero

Reaction kinetics of ultracold molecule-molecule collisions

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