Question

Hi, This is one of my chem hw problems. Does anyone have links to websites that might help me solve this..or equations? It sounds like there are two parts to the question but I'm not sure. Volts and Joules?

1. Electrons are used to determine the structure of crystal surfaces. To have diffraction, the
wavelength, λ, of the electrons should be on the order of the lattice constant, which is typically 0.30
nm. What energy do such electrons have, expressed in electron-volts and joules?

Answer 1

Expressed in joules.
E = hc/lambda.
E will be in joules. h is Planck's constant, c is speed of light in m/s, and lambda is in meters. Convert 0.3 nm to meters which will be 0.3 x 10^-9 m. You can look in your text, often on the inside of front OR back cover, for joules to ev conversion factor.

Answer 2

Thanks!