In 1993 , it was discovered that when C60 is put under pressure of about 3 bar of Helium or Neon , He NNP C60 and Ne NNP C60 are made . In 1993 , it was discovered that when C60 is exposed to a pressure of around 3 bar of He or Ne , the complexes He NNP C60 and Ne NNP C60 are formed .