16:00-17:00
Quantum Mechanical Depth Distribution Function Calculated by Multiple Scattering Theory
Dr. Hiroshi Shinotsuka（Advanced Surface Chemical Analysis Group, Advanced Nano Characterization Center）
-
The emission depth distribution function (EDDF) is an important parameter in surface analysis. EDDF for the photoemission is a detected probability in a given direction as a function of emitter depth. We sometimes see a non-exponential decay because of elastic scatterings from composite atoms in solids. There are several classical approaches to calculate EDDF [1, 2], which successfully describe the EDDF in the high energy region. But they are based on the classical theory and the jellium model, so that they did not consider atomic structures in a solid. On the contrary, we study the EDDF based on the quantum mechanical multiple scattering theory [3, 4]. In this approach, we can take the details of atomic structures and the interference effects into account which has not been considered in the classical theory. It is shown that we need full multiple scattering calculations to properly evaluate the EDDF.
We have discussed the EDDF only from simple metals, and normal emissions excited by a linearly polarized X-ray whose polarization is normal to the surface [4]. But it was not enough to discuss the characteristic shape of the EDDF as seen in the experiment [1], in which the X-ray polarization is parallel to the surface. Taking the experimental geometry into account, we now calculate photoelectron yield from some metal oxides and take average of it over an analyzer acceptance angle. It has been seen the EDDF shows almost exponential decay when the photoelectron is detected at 60 degree from surface normal. We also study the angular dependence of the EDDF, and investigate the importance of the structural effect on EDDF. The results of our calculation will be shown and compared with the experiment.
References
[1] I. S. Tilinin, A. Jablonski, J. Zemek and S. Hucek, J. Elect. Spect. 87 (1997) 127-140.
[2] A. Jablonski, Surf. Sci. 586 (2005) 115-128.
[3] T. Fujikawa, J. Phys. Soc. Jpn. 54 (1985) 2747-2753.
[4] H. Shinotsuka, H. Arai and T. Fujikawa, Phys. Rev. B 77 (2008) 085404.
