Collisions of rare gas ions with C60: Endohedral formation, energy transfer, and scattering dynamics

Abstract

Rovibrationally selected ion-molecule collision study using the molecular beam vacuum ultraviolet laser pulsed field ionization-photoion method: Charge transfer reaction of N2 +(X 2Σg +; v+ = 0-2; N + = 0-9) + Ar A selected-ion-flow-drift-tube study of charge transfer processes between atomic, molecular, and dimer ion projectiles and polyatomic molecules ethane, propane, and n-butane Scattering of rare gas cations from C 60 has been studied in a guided-beam tandem mass spectrometer. Charge transfer ͑CT͒ is observed to be the dominant channel over the collision energy range from 0 to 100 eV, but dissociative CT and endohedral complex formation are significant at high collision energies. The threshold energies for endohedral penetration are found to be proportional to rare gas atom size. Our CT and dissociative CT data allow us to make several conclusions about the nature of energy transfer in rare gas-fullerene collisions. Surprisingly, the conclusion is that the energy transfer distribution must be sharply bimodal, with ϳ85% of collisions resulting in little collision-to-internal energy transfer, and ϳ15% of collisions being essentially 100% inelastic. The results indicate that the dissociative CT and endocomplex formation channels are closely related.

High-resolution kinetic energy release distributions and dissociation energies for fullerene ions Cn+, 42⩽n⩽90

“…28 Very few experiments on fullerenes have been performed where this energy has been controlled directly, such as in sticking collisions at hyperthermal energies; 29,30 those results, though, pertain to collision complexes ͑endohedral fullerenes͒. ͑4͒ is the vibrational excitation energy of the metastable complex from which the emission temperature T e is computed.…”

The dynamics of endohedral complex formation in surface pick-up scattering as probed by kinetic energy distributions: Experiment and model calculation for Cs@C60+

“…Our proposed impulsive mechanism assumes the lift-off of the endohedral complex following Cs ϩ intracage scattering events. 13 In the Xe ϩ /C 60 collision experiments, no Xe@C 60 ϩ was observed. Is it possible that the just-formed Cs@C 60 will remain on the surface for a much longer time ͑say up to 100 ps͒, equilibrate with a long-lived local hot spot ͑LHS͒ ͑with vibrational energy contributions from both the adsorbed Cs@C 60 and some surface subunit͒, and then thermally desorb off the surface?…”

“…The time scale involved is subps. The abrupt appearance of the Rg@C 56 ϩ in the abundance distribution 13 can point at the last mechanism. In the following, based on theoretical considerations and experimental observations we will argue against this mechanism.…”

Collision energetics in a tandem time-of-flight (TOF/TOF) mass spectrometer with a curved-field reflectron

“…A molecular dynamics simulation predicts the maximum yield at a laboratory collision energy of 8 keV [13], though the maximum yield in our experiments (see below) was observed at 6 keV (33 eV in the center-of-mass frame) [12]. Most of the experiments involving high-energy collisions of fullerenes have been carried out using sector instruments or time-of-flight mass spectrometers combined with a retarding field energy analyzer [10][11][12][13][16][17][18]20,21]. In this investigation we detect heliumtrapped fragments using a unique time-of-flight mass analyzer with a curved field reflectron.…”

“…In the case of the spherical fullerene C 60 molecule it is also possible to capture different targets [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. For noble gas atoms this interaction does not involve the formation of a chemical bond.…”