Cold and controlled chemical reaction dynamics

Toscano, Jutta; Lewandowski, H. J.; Heazlewood, Brianna R.

doi:10.1039/d0cp00931h

Cited by 59 publications

(50 citation statements)

References 166 publications

(205 reference statements)

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“…Many book chapters and review articles on gas-phase chemical dynamics feature reactions involving radical species. [14][15][16][17][18][19]22,[31][32][33][34][35][36] And yet, many decades after the first experimental studies of radical reaction dynamics, there are still unanswered questions about how paramagnetic species react-both in terms of the general behaviour exhibited, and when considering specific reaction systems. For example, the F + H 2 reaction system has been extensively and actively studied, both experimentally and theoretically, for more than 50 years.…”

Section: Early Experimental Studiesmentioning

confidence: 99%

Low-temperature reaction dynamics of paramagnetic species in the gas phase

Miossec

Heazlewood

2022

Chem. Commun.

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Section: Early Experimental Studiesmentioning

confidence: 99%

Low-temperature reaction dynamics of paramagnetic species in the gas phase

Miossec

Heazlewood

2022

Chem. Commun.

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“…Advances in the experimental studies of ion-molecule reactions near 0 K have been recently made that rely on the use of laser-cooled and sympathetically cooled ions in ion traps and Coulomb crystals. 9,[37][38][39] Our own approach to study ionmolecule reactions at low energies consists of suppressing the stray-electric-field-induced heating of the ions by replacing the ion by an atom or molecule in a Rydberg state of high principal quantum number n. [40][41][42][43] In such states, the Rydberg electron moves on an orbit of large radius (pn 2 , e.g., E50 nm for n = 30), without significantly affecting the reactions involving the ion core. [44][45][46] The distant Rydberg electron, however, effectively shields the reaction from stray electric fields.…”

Section: Introductionmentioning

confidence: 99%

Multipole-moment effects in ion–molecule reactions at low temperatures: part I – ion-dipole enhancement of the rate coefficients of the He⁺ + NH₃ and He⁺ + ND₃ reactions at collisional energies E_coll/k_B near 0 K

Zhelyazkova

Martins

Agner

et al. 2021

Phys. Chem. Chem. Phys.

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“…There have also been a number of studies involving non-reactive collisions between neutral species under cold conditions. Readers are directed to recent review articles for a detailed discussion of inelastic scattering under cold conditions 131,132 .…”

Section: From 1 K Down To a Few 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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Cold and controlled chemical reaction dynamics

Abstract: State-to-state chemical reaction dynamics, with complete control over the reaction parameters, offers unparalleled insight into fundamental reactivity.

Cited by 59 publications

References 166 publications

Low-temperature reaction dynamics of paramagnetic species in the gas phase

Low-temperature reaction dynamics of paramagnetic species in the gas phase

Multipole-moment effects in ion–molecule reactions at low temperatures: part I – ion-dipole enhancement of the rate coefficients of the He⁺ + NH₃ and He⁺ + ND₃ reactions at collisional energies E_coll/k_B near 0 K

Towards chemistry at absolute zero

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Cold and controlled chemical reaction dynamics

Abstract: State-to-state chemical reaction dynamics, with complete control over the reaction parameters, offers unparalleled insight into fundamental reactivity.

Cited by 59 publications

References 166 publications

Low-temperature reaction dynamics of paramagnetic species in the gas phase

Low-temperature reaction dynamics of paramagnetic species in the gas phase

Multipole-moment effects in ion–molecule reactions at low temperatures: part I – ion-dipole enhancement of the rate coefficients of the He+ + NH3 and He+ + ND3 reactions at collisional energies Ecoll/kB near 0 K

Towards chemistry at absolute zero

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Multipole-moment effects in ion–molecule reactions at low temperatures: part I – ion-dipole enhancement of the rate coefficients of the He⁺ + NH₃ and He⁺ + ND₃ reactions at collisional energies E_coll/k_B near 0 K