ok, i did a lab and found values of the diameter of the electron rings after diffraction from a graphite. i also have the voltage that i accelerate the electrons to hit the graphite. so to find the distance between adjacent planes of graphite carbon "d", we use bragg's diffraction law right? 2dsin(theta) = n(lamda) but the problem is what if i need to find the interatomic distance "a" between the carbon atoms on the same plane. is there some sort of equation or law i can use to find this distance from the experiment data that i obtained above? i don't seem to recall any. and also, am i right to say, the outer diffraction ring is caused by the diffraction between atoms of the same plane (interatomic) whereas the inner diffraction ring is caused by the diffraction between layers of atoms "d" given by bragg's law? thanks a ton!