Infrared multiphoton electron detachment spectroscopy of C_76~2

摘要

In this letter, we report the first infrared spectrum of C. This multiply charged anion has beenstudied in an electrodynamic ion trap held at room temperature using tunable infrared radiation froma free-electron laser. Resonant vibrational excitation is found to cause electron detachment and theresulting singly negatively charged as well as the remaining doubly charged parent ion aremonitored as a function of IR wavelength in an experimental scheme that we term infraredmultiphoton electron detachment spectroscopy. The obtained IR spectra are contrasted to computedvibrational spectra using density functional theory. The dianionic molecule retains its overallsymmetry (i.e., D_2point group) with a ~1A _1ground state respect to the neutral fullerene. Spectralshifts of characteristic tangential modes relative to the neutral cage are shown to originate from theexcess charge density.