Question: A gas of C60 molecules was created in an oven at temperature T. A beam of molecules escaped through a small hole in the oven, passed through the diffraction grating, and was detected at a distance of 1.2 m from the grating. The number of molecules detected as a function of the detector's distance from the center line is shown in Fig.
a. From their data the experimenters determined the de Broglie wavelength of the C60 molecules was 4.6 pm. What was the distance between neighboring slits in the diffraction grating?
Fig. - Interference pattern of c60 molecules (buckyballs) obtained by Nairz et al., "Quantum interference experiments with large molecules," Am. J. Phys.
b. How fast were the C60 molecules moving?
c. Estimate the temperature T of the oven assuming that the molecular speed you found in part (b) is ≈ vrms of the molecules in the oven.
d. Suppose that helium atoms (mass = 4 u) were used instead of C60 molecules and that the same interference pattern was found. Find the ratio between the speed of the He atoms and the speed of the C60 molecules.