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Homework Statement
Buckyballs are soccerball-shaped molecules consisting of 60 carbon atoms (Mass of C60 = 1.2024×10-24 kg) with an approximate diameter of 1 nm. A beam of buckyballs with each molecule carrying a kinetic energy of 0.60 eV is normally incident on a grating with a slit with of 10 nm and 105 lines per centimeter. We detect these molecules with suitable equipment placed at a distance of 1.5 m behind the grating. Let the wavelength of these buckyballs be λ.
(1) How far do we have to move the detector from the path of incidence to find the first maximum of intensity?
(2) If a photon had the same energy E as a buckyball of momentum p, what would be its wavelength λφ? Give an algebraic answer in terms of mC60, h, and c only.
Homework Equations
(I) d sin(θ) = ±mλ, where m is an integer.
(II) p2/(2m) = E
(III) pφ = E/c
(IV) E = hc/λφ
The Attempt at a Solution
For (1), the maximae occur at integral multiples of the wavelength, so the detector should be moved λ wavelengths away (or so I think).
For (2), cross multiply equation (III) to get E = pc. Set this equal to (I) yielding p = 2mC60c. Plug equation (IV) into (III) yielding p = h/λφ. Therefore 2mC60c = h/λφ. Trivial algebra gives the desired solution λφ = h/(2mC60c)
My solution to problem (1) feels too simple to be right, and my solution to problem (2) assumes that p = pφ, and I'm unsure as to whether such an equivalence is correct. Any help?