We have studied the fundamental rotational relaxation and excitation collision of OHˉJ = 0 ↔ 1 with helium at different collision energies. Using state-selected photodetachment in a cryogenic ion trap, the collisional excitation of the first excited rotational state of OHˉ has been investigated and absolute inelastic collision rate coefficients have been extracted for collision temperatures between 20 and 35 K. The rates are compared with accurate quantum scattering calculations for three different potential-energy surfaces. Good agreement is found within the experimental accuracy, but the experimental trend of increasing collision rates with temperature is only in part reflected in the calculations.



Research Center/Lab(s)

Center for High Performance Computing Research


This work has been supported by the European Research Council under ERC Grant Agreement No. 279898 and by the Austrian Science Fund (FWF) through Project No. P29558- N36. E.S.E. acknowledges support from the Fonds National de la Recherche Luxembourg (Grant No. 6019121). R.D. is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences (Award No. DE-SC0019740).

International Standard Serial Number (ISSN)

2469-9926; 2469-9934

Document Type

Article - Journal

Document Version

Final Version

File Type





© 2021 American Physical Society (APS), All rights reserved.

Publication Date

01 May 2021

Included in

Chemistry Commons