Only about one out of every 650,000 C60 were found with a helium atom . But with more pressures ( about 3000 bar ) , it is possible to get as much as 0.1 % .
Under these conditions , only about one out of every 650,000 C60 cages was doped with a helium atom ; with higher pressures ( 3000 bar ) , it is possible to achieve a yield of up to 0.1 % .