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SUMMARY:Experimental implementation of X-ray powder diffraction by polychr
 omatic synchrotron radiation in the range of 20-30 keV
DTSTART;VALUE=DATE-TIME:20200713T143300Z
DTEND;VALUE=DATE-TIME:20200713T143400Z
DTSTAMP;VALUE=DATE-TIME:20260513T213514Z
UID:indico-contribution-1885@indico.inp.nsk.su
DESCRIPTION:Speakers: Boris Tolochko (Institute of solid state chemistry a
 nd mechanochemistry)\nThe aim of the work is to develop a method that allo
 ws X-ray phase analysis using a wide synchrotron radiation (SR) spectral b
 and (polychromatic radiation). This will make it possible to increase the 
 number of photons in the primary beam by 2-3 orders of magnitude and\, acc
 ordingly\, reduce the time for determining the composition of the sample t
 o nanoseconds.\n\nThe relationship between the angular dependence of the s
 cattering intensity of polychromatic radiation and the angular dependence 
 of the scattering intensity of monochromatic radiation by an object is des
 cribed by the Fredholm equation of the first kind and is an incorrect task
 . The solution of this equation in the case of significant experimental er
 rors (which is inevitable in experiments with extremely high time resoluti
 on) is quite problematic.\nThe idea of the method is to form a sharp short
 -wavelength boundary in the SR spectrum and approximate the X-ray diffract
 ion pattern from the polycrystalline sample by the sum of Gaussian peaks\,
  which allows one to determine the intensities and interplanar distances f
 rom polychromatic X-ray diffraction patterns using the procedure of minimi
 zation by peak parameters. Computer model experiments showed that in this 
 case\, the initial values of the peak parameters to minimize are determine
 d with sufficient accuracy for a successful procedure\, and the errors in 
 determining the interplanar distances and their corresponding intensities 
 are equal in order of magnitude to the errors associated with traditional 
 experiments.\nThe purpose of this work is the experimental implementation 
 of the proposed method\, debugging it on test samples and using fast proce
 sses to study.\nThe work is aimed at methodological support of the fundame
 ntal task - obtaining previously inaccessible information about the atomic
  structure of matter during fast processes (explosion\, solid-phase reacti
 ons). The results obtained will allow us to determine such process paramet
 ers as pressure\, temperature\, density and phase composition in the local
  region (several microns)\, as well as the dynamics of their changes in re
 al objects.\nTo date\, obtaining direct structural information about the s
 tate of a substance during fast-moving processes and the dynamics of its c
 hange has been impossible. This hindered the development of the theory of 
 fast-flowing chemical reactions and processes occurring in matter during t
 he passage of the front of shock and detonation waves. The use of polychro
 matic synchrotron radiation (SR) opens up new possibilities and will allow
  to obtain previously inaccessible information on the kinetics of phase fo
 rmation in explosion products after passing through a detonation wave.\nSy
 nchrotron radiation\, as a source of x-ray radiation\, has a number of uni
 que properties\, the main of which are a large flux intensity\, which allo
 ws the use of a very short exposure time (\n\nhttps://indico.inp.nsk.su/ev
 ent/24/contributions/1885/
LOCATION:
URL:https://indico.inp.nsk.su/event/24/contributions/1885/
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