Evanescent
From Nordan Symposia
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Origin
Latin evanescent-, evanescens, present participle of evanescere
Definition
- 1: tending to vanish like vapor
Description
An evanescent wave is a nearfield standing wave with an intensity that exhibits exponential decay with distance from the boundary at which the wave was formed. Evanescent waves are a general property of wave-equations, and can in principle occur in any context to which a wave-equation applies. They are formed at the boundary between two media with different wave motion properties, and are most intense within one-third of a wavelength from the surface of formation. In particular, evanescent waves can occur in the contexts of: optics and other forms of electromagnetic radiation, acoustics, quantum mechanics, and "waves on strings".
