Phys. Rev. A. 108, 062808 (2023)

Direct Measurement of Delayed-detachment Rate Constants of C7⁻

S. Iida^1,*, S. Kuma², J. W. Niman³, S. Masuda¹, H. Tanuma¹, P. Ferrari⁴, K. Hansen^5,6, H. Shiromaru¹, and T. Azuma^2,1

1 Department of Physics, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan

2 Atomic, Molecular and Optical Physics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan

3 Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089-0484, USA

4 Radboud University, Institute for Molecules and Materials, HFML-FELIX, 6525 ED Nijmegen, Netherlands

5 Center for Joint Quantum Studies and Department of Physics, School of Science, Tianjin University, Tianjin 300072, China

6 Lanzhou Center for Theoretical Physics, Key Laboratory of Theoretical Physics of Gansu Province,Lanzhou University, Lanzhou, Gansu 730000, China

* s-iida@tmu.ac.jp

Abstract

Delayed electron detachment induced by resonant two-photon excitation of C7− is observed using an electrostatic ion storage ring. Radiative cooling during the period of more than 100 ms storage considerably narrows the initially very broad internal energy distributions resulting in the delayed detachment profiles to be well fitted by single-exponential functions. The time constants of the decay, representing the electron detachment rate constants, are found to be much smaller than the theoretically predicted ones based on the detailed balance theory employing the state density of the harmonic vibrations.