Application of electrospray ionization to the observation of higher fullerene anions

Negative‐ion electrospray mass spectrcmetry for the detection of higher fullerene anions is discussed. The fullerenes were reduced in dimethoxyethane/aromatic solvent using NaK amalgam and analyzed by electrospray ionization mass spectrometry using a double‐focusing mass spectrometer. All the C ions ( n = 2 k , and k is an integer) could be detected up to n = 102 except for 60 < n < 70 and n = 72. The detection efficiency of C 76 is found to be considerably lower than that for C 78 , probably because the C ion reacts further in solution and is converted to undetectable reaction products. In addition to the fullerene anions, large peaks due to methoxy‐substituted fullerene anions, C n (OCH 3 ) , are observed. The intensities of these ions grow with time.