Enhancing reactivity of SiO${}^{+}$ ions by controlled excitation to extreme rotational states

Abstract

Optical pumping of molecules provides unique opportunities for control of chemical reactions at a wide range of rotational energies. This work reports a chemical reaction with extreme rotational excitation of a reactant and its kinetic characterization. We investigate the chemical reactivity for the hydrogen abstraction reaction SiO${}^{+}$ + H${}_2$ $\to$ SiOH${}^{+}$ + H in an ion trap. The SiO${}^{+}$ cations are prepared in a narrow rotational state distribution, including super-rotor states with rotational quantum number $(j)$ as high as 170, using a broad-band optical pumping method. We show that the super-rotor states of SiO${}^{+}$ substantially enhance the reaction rate, a trend reproduced by complementary theoretical studies. We reveal the mechanism for the rotational enhancement of the reactivity to be a strong coupling of the SiO${}^{+}$ rotational mode with the reaction coordinate at the transition state on the dominant dynamical pathway.

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Cited by in corpus (2)

• Opposite effects of the rotational and translational energy on the rates of ion-molecule reactions near $0\text{K}$: the ${\text{D}}_2^{+}+{\text{NH}}_3$ and ${\text{D}}_2^{+}+{\text{ND}}_3$ reactions
• Autodetachment of diatomic carbon anions from long-lived high-rotation quartet states