# Instrumentation for Energy-Loss Spectroscopy

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## Abstract

*J*(

*x*,

*y*,

*θ*

_{ x },

*θ*

_{ y },

*E*) as a function of position (specified by coordinates

*x*and

*y*) on the specimen, as a function of the coordinates of angular deflection

*θ*

_{ x }and

*θ*

_{ y }, and as a function of energy loss

*E*. Even if such a procedure were technically feasible, it would involve storing a very large amount of data, so in practice an energy-loss experiment records one of the following:

- (a)
The intensity

*J*(*x*,*y*) or*J*(*θ*_{ x },*θ*_{ y }), for a given value of*E*or a specified range of energy loss. These data correspond to an energy-filtered image or diffraction pattern, and can be obtained using either scanning-beam (STEM) or fixed-beam (CTEM) techniques, as discussed in Section 2.4. - (b)
The intensity

*J*(*E*) at a given point on the specimen or, more precisely, ∫*J*(*E*)*dx dy*, where the limits of integration are defined by*x*^{2}+*y*^{2}=*d*^{2}/4,*d*being the diameter of the incident beam. Here were are referring to energy-loss spectroscopy (or energy analysis) carried out using a double-focusing spectrometer such as the magnetic prism (Sections 2.1.1 and 2.2). - (c)
The intensity

*J*(*y*,*E*) for a fixed value of the spatial coordinate*x*, or*J*(*θ*_{ y },*E*) for a given*θ*_{ x }. This involves energy analysis along a line drawn through the specimen or its diffraction pattern and requires a spectrometer which focuses only in the direction of dispersion, such as the Möllenstedt analyzer (Section 2.1.4) or the Wien filter (Section 2.1.3).

## Keywords

Energy Resolution Wien Filter Chromatic Aberration Fringe Field Readout Noise## Preview

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