roughly speaking, historically, Q=2pi/d is used by physicists and S=1/d used by crystallographers and these communities define their reciprocal lattices and Fourier transforms accordingly. With the 2pi in there, Q is the momentum transfer. Without it in there the Laue Equations are much cleaner.
Physicists are good at working in reduced units, like setting c=1. We can resolve the problem by setting 2pi=1! S On 2/21/07, Ray Osborn <[EMAIL PROTECTED]> wrote:
On 2007/02/21 9:06, "Jonathan Wright" <[EMAIL PROTECTED]> wrote: > 2pi/d just needs a better name than Q? I guess, to some extent, this debate depends on whether you are only interested in talking to other powder diffraction specialists. As a non-specialist, I would suggest that Q is a more widely used variable - certainly in the inelastic scattering community, but also I believe in the liquids and amorphous community, who might be interested in studying crystallization processes, for example. If I want to check the elastic scattering contained within my inelastic spectrum, it is certainly an inconvenience having to convert from two-theta, even assuming I know the wavelength. I certainly hope you don't settle on 10^4/d^2. Regards, Ray -- Dr Ray Osborn Tel: +1 (630) 252-9011 Materials Science Division Fax: +1 (630) 252-7777 Argonne National Laboratory E-mail: [EMAIL PROTECTED] Argonne, IL 60439-4845
-- Prof. Simon Billinge Department of Physics and Astronomy 4268 Biomed. Phys. Sciences Building Michigan State University East Lansing, MI 48824 tel: +1-517-355-9200 x2202 fax: +1-517-353-4500 email: [EMAIL PROTECTED] home: http://nirt.pa.msu.edu/
