High formation yields of negative ions in multicharged fluorine $\chem{F^{{\it q}+}}$$\mth{(q=1\tx{--}3)}$-$\chem{C_{60}}$ collisions

S. Martin; L. Chen; J. Bernard; R. Brédy; M. C. Buchet-Poulizac; X. Ma; B. Wei

doi:doi:10.1209/epl/i2006-10055-3

Europhys. Lett., 74 (6), pp. 985-991 (2006)
DOI: 10.1209/epl/i2006-10055-3

High formation yields of negative ions in multicharged fluorine $\chem{F^{{\it q}+}}$ $\mth{(q=1\tx{--}3)}$ - $\chem{C_{60}}$ collisions

S. Martin¹, L. Chen¹, J. Bernard¹, R. Brédy¹, M. C. Buchet-Poulizac¹, X. Ma² and B. Wei^{1, 2}

¹ Laboratoire de Spectrométrie Ionique et Moléculaire, Université Claude Bernard Lyon 1, UMR CNRS no. 5579 - 43 boulevard du 11 Novembre 1918 69622 Villeurbanne Cedex, France
² Institute of Modern Physics, Chinese Academy of Sciences - Lanzhou 730000, PRC

received 9 March 2006; accepted in final form 24 April 2006
published online 24 May 2006

Abstract
We have measured the yield of negative fluorine ions in F^q+( $q=1\tx{--}3$ )-C₆₀ collisions at low velocity ( $v \approx 0.18\un{a.u.}$ ). These yields are found surprisingly high, up to 7.1% for F⁺ and 1.1% for F³⁺, much higher than the yields measured with atomic targets, typically 0.1%. From the measured kinetic energy loss of scattered F^- ions we have estimated the impact parameter of the collision. A direct population of the ground state of the negatively charged projectile by a collective electron transfer is proposed as a possible mechanism to account for the high negative ion formation yields.

High formation yields of negative ions in multicharged fluorine - collisions

High formation yields of negative ions in multicharged fluorine $\chem{F^{{\it q}+}}$ $\mth{(q=1\tx{--}3)}$ - $\chem{C_{60}}$ collisions