Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Calculation of Intensity of of AX crystals

  1. Mar 3, 2015 #1
    I'm still confuse on using the equation about atomic scattering factor, f = a*e^(-b+((sin(theta)/lamda)^2) + c (general equation),

    where sin(theta)/lamda = 1/2d = 1/(2*(sqrt(a^2/(h^2 + k^2 +l^2)))), so this term is dependent on the plane.
    which you will used to find the Intensity of crystals in a certain plane. I = F^2 (disregard multiplicity factor, absorption and etc.), F = f*cos(2pi(hx + ky + lz)) (i omitted the isine part)

    so given a compound NaCl where a, b and c are also given, i try to so solve I in 111 plane.

    first i solve fNa and fCl using the equation above, this gives 26.30, and 23.71 respectively, and substitute to the equation of intensity i got I(NaCl)=106.44, but when i'm try to check using related literature, some website (http://pd.chem.ucl.ac.uk/pdnn/diff2/structf.htm) and its jcpds, my answer was wrong so please enlighten me about this matter.

    constant i used:
    for Na:
    a1Na=3.2565;b1Na=2.6671;a2Na=23.9362;b2Na=6.1153;a3Na=1.3998;b3Na=0.2001;a4Na=1.0032;b4Na=14.039;c1Na=0.404;
    for Cl:
    a1Cl=18.2915;b1Cl=0.0066; a2Cl=17.604; b2Cl=1.1717;a3Cl=6.5337;b3Cl=19.5424;a4Cl=2.3386;b4Cl=60.4486;c1Cl=-16.378;
     
  2. jcsd
  3. Mar 3, 2015 #2
    The formula for the atomic (or ionic) scattering factor given here

    http://scripts.iucr.org/cgi-bin/paper?sh0059

    is

    [itex]
    f(s) = \sum\limits_{i=1}^{4}a_i \exp(-b_i s^2) +c \\
    s = \sin(\theta)/\lambda = Q/4\pi = 1/2d
    [/itex]

    (you have a "+" which is probably a typo)

    You should use the scattering factors for the ions, Na+ and Cl-

    The constants given in the paper look a bit different from yours, but I have not checked every one of them.
     
  4. Mar 3, 2015 #3
    Last edited: Mar 3, 2015
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Calculation of Intensity of of AX crystals
Loading...