A shock-induced mechanism for the creation of organic molecules

Complex carbon-based molecules are everywhere in the Cosmos.  How many of these molecules are formed is still something of a mystery, particularly for carbon molecules formed by nature on primordial Earth that gave rise ...

A new type of super-resolution chemical microscopy

Conventional experiments in chemistry and biology study the behavior of the two, but it has been an abiding scientific challenge for scientists to observe, manipulate and measure the chemical reactions of individual molecules.

Optical superoscillation without side waves

Optical superoscillation refers to a wave packet that can oscillate locally in a frequency exceeding its highest Fourier component. This intriguing phenomenon enables production of extremely localized waves that can break ...

Transformation toughening of ceramics made crystal clear

Ceramic materials that are resistant to cracking are used in a variety of industries from aerospace engineering to dentistry. Toughening them to improve their efficiency and safety is therefore an important area of investigation. ...

Enantiomorph distribution maps for metals and metallic alloys

Left- or right-handedness is a symmetry property that many macroscopic objects also exhibit and which is of immense importance, particularly for the bioactivity of organic molecules. Chirality is also relevant for physical ...

New insights into switchable MOF structures

Metal-organic framework compounds (MOFs) consist of inorganic and organic groups and are characterized by a large number of pores into which other molecules can be incorporated. MOFs are therefore interesting for many applications, ...

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Diffraction

Diffraction refers to various phenomena which occur when a wave encounters an obstacle. Italian scientist Francesco Maria Grimaldi coined the word "diffraction" and was the first to record accurate observations of the phenomenon in 1665. In classical physics, the diffraction phenomenon is described as the apparent bending of waves around small obstacles and the spreading out of waves past small openings. Similar effects occur when light waves travel through a medium with a varying refractive index or a sound wave through one with varying acoustic impedance. Diffraction occurs with all waves, including sound waves, water waves, and electromagnetic waves such as visible light, x-rays and radio waves. As physical objects have wave-like properties (at the atomic level), diffraction also occurs with matter and can be studied according to the principles of quantum mechanics.

Richard Feynman said that

He suggested that when there are only a few sources, say two, we call it interference, as in Young's slits, but with a large number of sources, the process is labelled diffraction.

While diffraction occurs whenever propagating waves encounter such changes, its effects are generally most pronounced for waves where the wavelength is roughly similar to the dimensions of the diffracting objects. If the obstructing object provides multiple, closely spaced openings, a complex pattern of varying intensity can result. This is due to the superposition, or interference, of different parts of a wave that traveled to the observer by different paths (see diffraction grating).

The formalism of diffraction can also describe the way in which waves of finite extent propagate in free space. For example, the expanding profile of a laser beam, the beam shape of a radar antenna and the field of view of an ultrasonic transducer can all be analysed using diffraction equations.

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