Experimental studies on photoabsorption by endohedral fullerene ions with a focus on Xe@C60+ confinement resonances

Abrief overview on the status of experimental investigations into photoionization and fragmentation of fullerenes and endohedral fullerenes by absorption of a single short-wavelength photon is presented. The focus of this paper is on the endohedral Xe@C-60(+) molecular ion in which a xenon atom is centrally encapsulated inside a C-60(+) fullerene cage. Confinement resonances that result fromthe interference ofXe photoelectronmatterwaves emerging fromthe C-60(+) cavitywere studied by exposing Xe@C-60(+) ions to synchrotron radiation of 60 to 150.eV energy which is the region of the well-known giant atomic Xe d4 excitation resonance. Photoions Xe@C-n(q+) (with final charge states q = 2, 3, 4 of the product ions and numbers n = 60, 58, 56, 54 of carbon atoms left in the cage) were recorded as a function of photon energy and cross sections for the individual reaction channels were determined. In addition to previouswork, newfinal channels (q = 2; n = 60, 58 and q = 4; n = 58, 56) were observed, and thus, about 70% of the oscillator strength expected for the encapsulated Xe atom in the investigated energy range could be recovered. The present results establish the first and, so far, only conclusive experimental observation of confinement resonances in an endohedral fullerene. The data are in remarkable agreement with relativistic R-matrix calculations that accompanied the previous experimental work.

Automated summary

This paper provides an overview of experimental investigations into the photoionization and fragmentation of fullerenes and endohedral fullerenes by absorption of a single short-wavelength photon. The study focused on the behavior of the Xe@C-60(+) molecular ion and discovered new reaction channels, recovering about 70% of the expected oscillator strength for the encapsulated Xe atom in the investigated energy range. The results are in agreement with previous relativistic R-matrix calculations.