Publication

Refocusing with chirped pulses for broadband excitation without phase dispersion

Geoffrey Bodenhausen
1989
Journal Articles

Abstract

In chirped spectroscopy, the phase dispersion in NMR was removed by refocusing the magnetization to form an echo. The method by which this was obtained is described. Chirped spectra of a mixt. of CHCl3, CH2Cl2, acetone, cyclohexane, and dioxane was obtained and discussed. [on SciFinder (R)]

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Geoffrey Bodenhausen
1989
Journal Articles

Abstract

Official source

Related concepts (32)

Spin echo

In magnetic resonance, a spin echo or Hahn echo is the refocusing of spin magnetisation by a pulse of resonant electromagnetic radiation. Modern nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) make use of this effect. The NMR signal observed following an initial excitation pulse decays with time due to both spin relaxation and any inhomogeneous effects which cause spins in the sample to precess at different rates. The first of these, relaxation, leads to an irreversible loss of magnetisation.

Chirp

A chirp is a signal in which the frequency increases (up-chirp) or decreases (down-chirp) with time. In some sources, the term chirp is used interchangeably with sweep signal. It is commonly applied to sonar, radar, and laser systems, and to other applications, such as in spread-spectrum communications (see chirp spread spectrum). This signal type is biologically inspired and occurs as a phenomenon due to dispersion (a non-linear dependence between frequency and the propagation speed of the wave components).

Ultrashort pulse

In optics, an ultrashort pulse, also known as an ultrafast event, is an electromagnetic pulse whose time duration is of the order of a picosecond (10−12 second) or less. Such pulses have a broadband optical spectrum, and can be created by mode-locked oscillators. Amplification of ultrashort pulses almost always requires the technique of chirped pulse amplification, in order to avoid damage to the gain medium of the amplifier. They are characterized by a high peak intensity (or more correctly, irradiance) that usually leads to nonlinear interactions in various materials, including air.

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Refocusing with chirped pulses for broadband excitation without phase dispersion

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