Mecanismos de alargamento de linhas espectrais atômicas

Abstract

Recebido em 14 de abril de 2016. Aceito em 22 de maio de 2016Os espectros de energia deátomos idealizados (isolados, parados e em temperatura 0K) são constituídos por um conjunto de linhas muito estreitas. Contudo, no mundo real, verifica-se que cada uma destas linhas são alargadas pela ação de vários tipos de influências externas. Uma discussão simplificadaé apresentada sobre seus mecanismos e como cada um deles atua isoladamente sobre as linhas espectrais. O caso de dois ou mais mecanismos atuando juntosé também considerado. Técnicas de afinamento de linha para relevantes aplicações são mencionadas, incluindo algumas que usam o controle da largura e da forma da linha laser. Palavras-chave: alargamento de linha, afinamento de linha, linha do laser.The energy spectra of idealized atoms (isolated, at rest and temperature 0K) are constituted by a set of very narrow lines. However, in the real world one verifies that each of these lines are enlarged by the action of various types of external influences. A simplified discussion is presented about their mechanisms and how each type of them acts isolated upon a thin spectral line. The case of two or more types of these mechanisms acting conjunctly is also considered. Line narrowing techniques for relevant applications are mentioned, including others using the control of the widths and the shapes of a laser line.

A new hydrochloric acid 2-0 band analysis: Two temperature study

“…This occurs probably due to the fact that Voigt profile is a convolution between the two models as previously mentioned by Sobel et al, 37 which then takes into account the collisional broadening from the Lorentz model, and the Doppler effect described by the Gaussian model. [38][39][40] Based on literature, 38,39 the Doppler broadening occurs predominantly at low pressures (pressures ≤0.001 atm), allowing this way that collisional effects on spectral line shape to be disregarded. However, a gas subjected to high pressures corresponds to a greater density of molecules, thus implying a greater number of collisions and giving rise to collisional broadening.…”

“…The line-broadening mechanisms have been discussed by several authors. [37][38][39][40][41][42][43][44] As cited by Buldyreva et al, 39 since a pressure range defines the line shape evolution according to the change in pressure and temperature, there are three types of schemes by which the width of a line varies namely, the Doppler regime, Dicke narrowing and the collisional regime. Even at extremely low pressures, the line width presents a finite value due to thermal motion of the molecule.…”