Rotational state-changing cold collisions of hydroxyl ions with helium

Understanding low-temperature molecular collisions is challenging, but using non-resonant photodetachment makes it possible to study the state-resolved dynamics of the inelastic collisions between hydroxyl ions and cold helium buffer gas. Cold molecules are important for many applications 1 , from f...

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Bibliographic Details
Published in:Nature physics 2015-06, Vol.11 (6), p.467-470
Main Authors: Hauser, Daniel, Lee, Seunghyun, Carelli, Fabio, Spieler, Steffen, Lakhmanskaya, Olga, Endres, Eric S., Kumar, Sunil S., Gianturco, Franco, Wester, Roland
Format: Article
Language:English
Subjects:
119/118
140/125
639/766/36/1120
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Anions
Atomic
Classical and Continuum Physics
Cold atoms
Collisions
Complex Systems
Condensed Matter Physics
Helium
Ions
letter
Low temperature
Mathematical and Computational Physics
Molecular
Optical and Plasma Physics
Photodetachment
Physics
Polyaromatic hydrocarbons
Scattering
Theoretical
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Summary:Understanding low-temperature molecular collisions is challenging, but using non-resonant photodetachment makes it possible to study the state-resolved dynamics of the inelastic collisions between hydroxyl ions and cold helium buffer gas. Cold molecules are important for many applications 1 , from fundamental precision measurements 2 , quantum information processing 3 , quantum-controlled chemistry 4 , to understanding the cold interstellar medium 5 . Molecular ions are known to be cooled efficiently in sympathetic collisions with cold atoms or ions 6 , 7 , 8 . However, little knowledge is available on the elementary cooling steps, because the determination of quantum state-to-state collision rates at low temperature is very challenging for both experiment and theory. Here we present a method to manipulate molecular quantum states by non-resonant photodetachment. Based on this we provide absolute quantum scattering rate coefficients under full quantum state control for the rotationally inelastic collision of hydroxyl anions with helium. Experiment and quantum scattering theory show reasonable agreement without adjustable parameters. Very similar rate coefficients are obtained for two different isotopes, which is linked to several quantum scattering resonances appearing at different energies. The presented method is also applicable to polyatomic systems and will help elucidate non-radiative processes in polyaromatic hydrocarbons and protein chromophores.
ISSN:1745-2473
1745-2481
DOI:10.1038/nphys3326