As a rule of thumb from optics, you need a wavelength at least twice the
distance or shorter between two points you want to resolve. That is why we
cannot do a diffraction experiment with visible light.
On the other hand, if the wavelength were much shorter, inaccuracies in
their positions would have a bigger detrimental effect on the diffraction
pattern, i.e., you would probably not get a diffraction pattern from an
American city or Mannheim/ Germany from xrays, but if you used light with
a wavelength of say 30 meters, you might (just a guess) observe something.
--
Tim Gruene
Institut fuer anorganische Chemie
Tammannstr. 4
D-37077 Goettingen
GPG Key ID = A46BEE1A
On Wed, 24 Jan 2007, Carlos Frazao wrote:
Hi,
I have once heard and recently read that "the diffraction event results from
the fact that both the X-rays wavelength and the atomic distances are of the
same magnitude". Although such a relation seems appealing I am unsure if this
is not a mere coincidence. Could someone clarify or lead me to a relevant
reading.
Cheers,
Carlos
--
**************************************
Dr. Carlos Frazao
Crystallography Department
ITQB-UNL, Av Republica, Apartado 127
2781-901 Oeiras, Portugal
Phone: (351)-214469666 FAX: (351)-214433644
e-mail: [EMAIL PROTECTED]
www.itqb.unl.pt
