Direct observation of C60− nano-ion gas phase ozonation via ion mobility-mass spectrometry

Abstract

Improved methods to probe the reactivity of nano-ions, such as C₆₀⁻, would find utility in nanochemistry, combustion chemistry, and in generally understanding the behavior of matter at the nanometer scale. We demonstrate that ion mobility-mass spectrometry (IM-MS) with a low-field differential mobility analyzer can be used to probe nano-ion reaction kinetics. We used the developed IM-MS approach to examine the gas phase reactivity of C₆₀⁻ ions with ozone at atmospheric pressure. Experimental results show that ozonation of C₆₀⁻ mainly leads to the formation of C₆₀O_n⁻. The controlled reaction time within the ion mobility instrument enables calculation of ozonation reaction rates and assuming oxygen atoms are added sequentially, we find that the reaction rate between C₆₀⁻ and O₃ is near the collision controlled limit. We propose an exponentially decaying reaction rate coefficient expression to describe ozonation leading to the addition of >20 oxygen atoms. At high ozone concentrations, CO or CO₂ loss from C₆₀O_n⁻ is additionally observed.