Why does silver have lower absorption than zirconium at 35 keV?

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SUMMARY

The discussion centers on the unexpected lower X-ray absorption of silver (Ag, atomic number 47) compared to zirconium (Zr, atomic number 40) at 35 keV. Despite silver's higher atomic number, its K-edge absorption occurs at 25 keV, while zirconium's K-edge is at 18 keV. The key finding is that the shape of the K-edge absorption curves explains this anomaly; silver exhibits a sharp rise followed by a gradual decrease in absorption, resulting in higher absorption at 35 keV compared to zirconium, despite its lower linear attenuation coefficient at 25 keV.

PREREQUISITES
  • Understanding of X-ray absorption and linear attenuation coefficients
  • Familiarity with K-edge absorption concepts
  • Knowledge of atomic numbers and their significance in material science
  • Basic principles of photon energy and its interaction with matter
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  • Research the principles of X-ray absorption spectroscopy (XAS)
  • Study the effects of atomic number on linear attenuation coefficients
  • Examine the characteristics of K-edge absorption in various materials
  • Explore the applications of X-ray techniques in material analysis
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Material scientists, physicists, and researchers involved in X-ray absorption studies or materials characterization will benefit from this discussion.

Myrddin
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so just about finishing a report on x ray abosprtion on different materials, generally the linear attneuation coefficient increases with atominc number Z. However silver(47) had a lower attenuation coefficient then zirconium(40) despite having the significantly higher value of Z.

With some reading found that the absorption edges ;where there is a rapid increase in absorption from photon matching the binding of a shell, depends on the energy of the x ray your using. So we thought this must explain our result with silver. Looking at the K shell :

Zirconium has Kedge absortpion at 18KeV
Silver has kedge absorption 25 KeV

Our supply voltage was 35Kv---> 35KeV , so why does zircmonium have more absortion?
 
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The answer lies in the fact that (K) edges of zirconium and silver have different shapes. The K edge of silver has a very sharp rise at 25 keV, but then a gradual decrease as energy increases. So even though the absorption was lower for silver than for zirconium at 25 keV, it still had more absorption at 35 keV due to its gradual decrease in absorption. Thus, the higher atomic number of silver did not necessarily lead to it having a higher linear attenuation coefficient than zirconium.