ISSRNS 2012: Abstracts / Synchrotron Radiation in Natural Science Vol. 11, No 1 – 2 (2012) P 13
THE DETERMINATION OF MOLECULAR STRUCTURE OF CHLOROANISOLES BY X-RAY DIFFRACTION
H. Drozdowski∗, A. Romaniuk, and Z. B laszczak Department of Optics, Faculty of Physics A. Mickiewicz University,
ul. Umultowska 85, 61–614 Pozna´n, Poland
Keywords: molecular function of structure, chloroanisoles, van der Waals atomic radii
∗e-mail : riemann@amu.edu.pl
For the first time the method of reduction pro- posed by Mozzi-Warren with modifications intro- duced by the Drozdowski [1] has been applied to verify the assumed models of the molecules studied and to separate the intra- from intermolecular in- teractions. Analysis of intramolecular interactions between pairs of atoms and intermolecular interac- tions has been made.
The molecular function of structure was cal- culated from the modified Debye formula [2]:
im(S) = Pn
i=1fi(S)−2
∗
"
Pn j.s
Pn i6=jfifj
exp(−u¯ij2S2sin(S ¯S ¯rrij)
ij )
# ,
which describes the scattering by a single molecule.
The values of the function Si(S) were calculated from equation [3]:
Si(s) = 1rRS2 S1
"
Pn
j,kK¯j4Πr2ρk(r)−
Pn
jK¯j4Πr2ρ0
#
sin(Sr)dr,
where r is the distance from an atom or molecule selected as scattering centre, ρk(r) the function of radial electron density, ¯Kj — the effective mean atomic numbers. The calculations were performed for a finite range of S values from S1= 0.430 ˚A−1to S2 = 14.311 ˚A−1. The modified method of Blum- Narten reductions was applied to verify the correct- ness of the assumed models of the molecules and to permit a separation of the intra- and intermolecular interactions. Analysis of the functions of the exper- imental i(S) and the calculated im(S) for the model proposed.
The molecular structural function im(S) was cal- culated from the equation of Debye for the Bragg
angle θ changing in the range 0◦ – 60◦. Having determined i(S) and im(S), the so-called distinct structure function [3] was obtained from equation:
id(S) = i(S) − im(s),
where im(S) is the molecular structure function de- scribing the scattering by a single molecule and id(S) is the distinct structure function providing the information abort intermolecular correlations from the experimental data. The dependencies of i(S), im(S) and id(S) on S are presented in Fig. 1.
The method of reduction proposed by Mozzi- Warren with the modifications introduced by the Drozdowski [1]-[3] applied in analysis of the scat- tered radiation intensity permitted establishment of the correct models of the molecules chloroanisoles [4].
References
[1] H. Drozdowski, “Structure of liquid 1-chloronaphthalene at 293 K,” J. Mol. Struct.
526 (2000) 391.
[2] H. Drozdowski, “Vibrations in atoms in liquid 1,4-dimethylbenzene,” Phys. Chem. Liq. 44 (2006), 21.
[3] H. Drozdowski, “The molecular structure of liq- uid 1-phenylnaphthalene by X-ray diffraction,” Acta Phys. Slovaca 51 (2001) 163.
[4] H. Drozdowski, A. Romaniuk, Z. B laszczak, “Short- range ordering in ortho-chloroanisole at 293 K by X-Ray diffraction,” Bull. Synchr. Radiat. Nat.
Science 8 (2009) 38.
Figure 1 : Curves - continuous lines — the experimental structure functions Si(S).
Curves - broken lines — the molecular structure functions im(S) calculated ac- cording to Debye. Curves - dotted lines — subtraction of the calculated curves from the experimental structure functions.
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