I have been doing an introductory XRD experiment in which we measure the crystal spacing of a simple lattice (LiF) and as usual obtained data for intensity against two theta. Ideally the peaks should be symmetric so my question is what is the main origin of asymmetry in the peaks? My best guess is it is some small misalignment which means one side of the peak will receive a higher intensity and vice versa, which is consistent with all of my peaks, however I'm not sure if this is definitely it. On a side note, is it valid to convert the intensity-angle spectrum to an intensity-wavelength spectrum via Braggs formula with n = 1 or should I also be considering the contribution of higher n also?
I've attached a picture as an example. Thanks in advance.