Soft x-ray scattering from rough surfaces: experimental and theoretical analysis

Area of Science:

• Optics and Photonics
• Surface Science
• Materials Science

Background:

• Specular and scattered radiation measurements are crucial for understanding surface properties.
• Existing theories like Beckmann's scalar theory provide a framework for analyzing light scattering from rough surfaces.
• The influence of optical constants on scattering phenomena requires further investigation.

Purpose of the Study:

• To measure and analyze specularly reflected and scattered radiation from artificially roughened mirrors and gold films.
• To evaluate the applicability of Beckmann's scalar theory and explore corrections using vector theory.
• To investigate scattering from gold films roughened by surface crystallization.

Main Methods:

• Measurements of specularly reflected and scattered radiation at wavelengths of 50, 100, and 200 Angstroms.
• Utilizing artificially roughened flat mirrors and thick vacuum-evaporated gold samples.
• Applying Beckmann's scalar theory with exponential autocorrelation functions and exploring vector theory corrections.

Main Results:

• Scattering from roughened mirrors agreed well with scalar theory, with parameters for mean roughness and autocorrelation length.
• Discrepancies in scalar theory were qualitatively corrected by considering optical constants via vector theory.
• Gold films roughened by crystallization exhibited different scattering distributions, not fitting scalar theory.

Conclusions:

• Beckmann's scalar theory is a reasonable model for scattering from uniformly roughened surfaces.
• Optical constants significantly influence scattering, necessitating vector theory for accurate modeling.
• Surface crystallization leads to scattering behaviors not explained by standard scalar diffraction theories.