Isomeric fullerene trimers have been prepared by using a high speed vibration milling technique, and Langmuir films of the isomers observed on Au(111) surfaces by scanning tunneling microscopy (STM). Each isomer exhibited a different surface morphology. The observed distribution of isomers supports molecular orbital calculations of isomer stability. STM may be used to distinguish the individual isomers (see image), which is difficult to achieve by spectroscopy.