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Page "X-ray fluorescence" ¶ 12
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wavelength and dispersive
X-rays, which are produced by the interaction of electrons with the sample, may also be detected in an SEM equipped for energy-dispersive X-ray spectroscopy or wavelength dispersive X-ray spectroscopy.
In a dispersive medium, the phase speed itself depends upon the frequency of the wave, making the relationship between wavelength and frequency nonlinear.
The directions of these beams depend on the spacing of the grating and the wavelength of the light so that the grating acts as the dispersive element.
The wavelength dependence in the grating equation shows that the grating separates an incident polychromatic beam into its constituent wavelength components, i. e., it is dispersive.
In wavelength dispersive analysis, the fluorescent X-rays emitted by the material sample are directed into a diffraction grating monochromator.
Figure 6: Schematic arrangement of wavelength dispersive spectrometer
In wavelength dispersive spectrometers ( WDX or WDS ), the photons are separated by diffraction on a single crystal before being detected.
Although wavelength dispersive spectrometers are occasionally used to scan a wide range of wavelengths, producing a spectrum plot as in EDS, they are usually set up to make measurements only at the wavelength of the emission lines of the elements of interest.
The velocity of these waves varies with wavelength, so they are said to be dispersive and the shape of the wavetrain varies with distance.
The Wavelength dispersive X-ray spectroscopy ( WDXRF or WDS ) is a method used to count the number of X-rays of a specific wavelength diffracted by a crystal.
Unlike the related technique of Energy dispersive X-ray spectroscopy ( EDS ) WDS reads or counts only the x-rays of a single wavelength at time, not producing a broad spectrum of wavelengths or energies simultaneously.
EDS is often contrasted with its spectroscopic counterpart, WDS ( wavelength dispersive X-ray spectroscopy ).
In a wavelength dispersive X-ray spectrometer the single crystal diffracts the photons ( Bragg's law ) which are collected by a detector.
Specific X-ray wavelengths are selected and counted, either by wavelength dispersive X-ray spectroscopy ( WDS ) or energy dispersive X-ray spectroscopy ( EDS ).
EBSD when used together with other in-SEM techniques such as cathodoluminescence ( CL ), wavelength dispersive X-ray spectroscopy ( WDS ) and / or energy dispersive X-ray spectroscopy ( EDS ) can provide a deeper insight into the specimen's properties.
Angle dispersive ( fixed wavelength ) instruments typically have a battery of individual detectors arranged in a cylindrical fashion around the sample holder, and can therefore collect scattered intensity simultaneously on a large 2θ range.

wavelength and analysis
The analysis of this system is simplified if we consider light of a single wavelength.
In general, a single wavelength is required for proper analysis, so, in order to selectively filter the light, it is passed through an excitation monochromator, and then that chosen wavelength is passed through the sample cell.
The analysis of the wave can be based upon comparison of the local wavelength with the local water depth.
This indeterminacy in wavelength in solids is important in the analysis of wave phenomena such as energy bands and lattice vibrations.
The analysis of the wave can be based upon comparison of the local wavelength with the local water depth.
* Infrared astronomy deals with the detection and analysis of infrared radiation ( this typically refers to wavelengths longer than the detection limit of silicon solid-state detectors, about 1 μm wavelength ).
The analysis of the wavelength dependence is generally not done using a monochromator as it is in UV-Vis, but with the use of an interferometer.
Upon the analysis of the change of polarization of light, which is reflected off a sample, ellipsometry can yield information about layers that are thinner than the wavelength of the probing light itself, even down to a single atomic layer.
Fluorescence microscopy with fluorescent reporter proteins has enabled analysis of live cells by fluorescence microscopy, however cells are susceptible to phototoxicity, particularly with short wavelength light.
Radio frequency engineering is the analysis and design of circuits at frequencies where transmission lines are comparable to the wavelength.
This is a simple case of dimensional analysis: the Schwarzschild radius is proportional to the mass, whereas the Compton wavelength is proportional to the inverse of the mass.
A fairly straightforward analysis of the kinematics of the coning action yields an estimate of the wavelength of the lateral oscillation:

wavelength and radiation
In short, the electrons of the atoms in the atomizer can be promoted to higher orbitals ( excited state ) for a short period of time ( nanoseconds ) by absorbing a defined quantity of energy ( radiation of a given wavelength ).
The radiation intensity emitted by these lamps is decreasing significantly with increasing wavelength, so that they can be only used in the wavelength range between 190 and about 320 nm.
In addition it is necessary that the lamp emits radiation of intensity at least an order of magnitude above that of a typical HCL over the entire wavelength range from 190 nm to 900 nm.
While the scientific community was once divided between supporters of the Big Bang and those of alternative cosmological models, most scientists became convinced that some version of the Big Bang scenario best fit observations after the discovery of the cosmic microwave background radiation in 1964, and especially when its spectrum ( i. e., the amount of radiation measured at each wavelength ) was found to match that of thermal radiation from a black body.
The electromagnetic spectrum, in order of increasing frequency and decreasing wavelength, consists of radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays.
For example, when electromagnetic radiation is absorbed by matter, particle-like properties will be more obvious when the average number of photons in the cube of the relevant wavelength is much smaller than 1.
In general, EM radiation ( the designation ' radiation ' excludes static electric and magnetic and near fields ) is classified by wavelength into radio, microwave, infrared, the visible spectrum we perceive as visible light, ultraviolet, X-rays, and gamma rays.
Rough plot of Earth's atmospheric transmittance ( or opacity ) to various wavelength s of electromagnetic radiation
EM radiation with a wavelength between approximately 400 nm and 700 nm is directly detected by the human eye and perceived as visible light.
is the wavelength of the electromagnetic radiation ( photon ) as measured by the observer.
is the wavelength of the electromagnetic radiation ( photon ) when measured at the source of emission.
In most cases, the emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation.
However, when the absorbed electromagnetic radiation is intense, it is possible for one electron to absorb two photons ; this two-photon absorption can lead to emission of radiation having a shorter wavelength than the absorbed radiation.
The emitted radiation may also be of the same wavelength as the absorbed radiation, termed " resonance fluorescence ".
The Kasha – Vavilov rule dictates that the quantum yield of luminescence is independent of the wavelength of exciting radiation.
A somewhat more reliable statement, although still with exceptions, would be that the fluorescence spectrum shows very little dependence on the wavelength of exciting radiation.
In 1944, Hendrik van de Hulst predicted microwave radiation at a wavelength of 21 cm resulting from interstellar atomic hydrogen gas ; this radiation was observed in 1951.

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