title: Vibrational cooling in a cold ion trap: vibrationally resolved photoelectron spectroscopy of cold C60(-) anions.
abstract: We demonstrate vibrational cooling of anions via collisions with a background gas in an ion trap attached to a cryogenically controlled cold head (10-400 K). Photoelectron spectra of vibrationally cold C60(-) anions, produced by electrospray ionization and cooled in the cold ion trap, have been obtained. Relative to spectra taken at room temperature, vibrational hot bands are completely eliminated, yielding well-resolved vibrational structures and a more accurate electron affinity for neutral C60. The electron affinity of C60 is measured to be 2.683+/-0.008 eV. The cold spectra reveal complicated vibrational structures for the transition to the C60 ground state due to the Jahn-Teller effect in the ground state of C60(-). Vibrational excitations in the two A(g) modes and eight H(g) modes are observed, providing ideal data to assess the vibronic couplings in C60(-).
authors.affiliation: Department of Physics, Washington State University, 2710 University Drive, Richland, Washington 99352, USA.
authors.forename: Xue-Bin
authors.initials: XB
authors.lastname: Wang
authors.forename: Hin-Koon
authors.initials: HK
authors.lastname: Woo
authors.forename: Lai-Sheng
authors.initials: LS
authors.lastname: Wang