Question

A certain crystal is cut so that the rows of atoms on its surface are separated by a distance of 0.352 nm. A beam of electrons is accelerated through a potential difference of 175 V and is incident normally on the surface. If all possible diffraction orders could be observed, at what angles (relative to the incident beam) would the diffracted beams be found? (The surface acts as a diffraction grating where maxima occur when d sin? = n?, n = 1,2,3...)

Answer 1

wavelength of electron = 12.27/v A^o

                                = 0.9275 A^o

for diffraction        dsin = n

for n= 1             0.352*10^-9₁ = 1*0.9275*10^-10

                                            ₁ =sin^-(0.2635) = 15^o17'

for n=2                                  ₂ = sin^-( 0.5269) = 31^o48^'

for n=3                                  ₃= sin^-(0.7904) = 52^o13^'