Wave-Matter Interaction: Diffraction and Diffusion Phenomena

This lecture covers the interaction of waves with matter, focusing on diffraction and diffusion phenomena. The instructor begins by reviewing the principles of wave refraction and reflection, emphasizing the coefficients of reflection and transmission. The discussion progresses to the principles of Fermat, which explain how waves behave at interfaces. The lecture then introduces diffraction, particularly Fresnel diffraction, and its significance when the dimensions of obstacles approach the wavelength of the wave. The instructor illustrates these concepts with experiments involving light passing through slits, demonstrating the resulting diffraction patterns. The lecture concludes with an exploration of diffusion, particularly in the context of X-ray interactions with matter, highlighting the historical significance of Röntgen's discovery of X-rays and their applications in understanding material structures. Throughout the lecture, the instructor emphasizes the mathematical relationships governing these phenomena, providing a comprehensive overview of wave behavior in various media.