4. XRF – X-Ray Fluorescence
X-ray fluorescence (XRF) spectrometry is an elemental analysis technique with broad application in science and industry. XRF is based on the principle that individual atoms, when excited by an external energy source, emit X-ray photons of a characteristic energy or wavelength. By counting the number of photons of each energy emitted from a sample, the elements present may be identified and quantitated. Modern XRF instruments are capable of analyzing solid, liquid, and thin-film samples for both major and trace (ppm-level) components. The analysis is rapid and usually sample preparation is minimal or not required at all.
The identification of elements by X-ray methods is possible due to the characteristic radiation
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It competes with the Auger effect, which results in emission of a second photoelectron to regain stability. The relative numbers of excited atoms that fluoresce are described by the fluorescence yield, which increases with increasing atomic number for all three series (Jenkins 1988: 6). High energy electrons are not the only particles which can cause ejection of photoelectrons and subsequent fluorescent emission of characteristic radiation. High-energy X-ray photons can create the same effect, allowing us to excite a sample with the output of an X-ray tube or any source of photons of the proper energy. In fact, in some applications of XRF spectrometry, X-rays from a tube are used to excite a secondary fluorescer, which emits photons that in turn are used to excite the sample. When X-rays impinge upon a material, besides being absorbed, causing electron ejection and subsequent characteristic photon emission, they may also be transmitted or scattered. When an X-ray is scattered with no change in energy this is called Rayleigh scattering, and when a random amount of energy is lost the phenomenon is Compton scattering. Scattered X-rays are usually problematic in XRF, creating high levels of background radiation (Anzelmo 1987 Part
Absorbance was defined as: log I_o/I where I_o is incident light and I is the transmitted light. Fluorescence emission spectrum is different from fluorescence excitation spectrum because it records different wavelengths of chemical s...
The endothermic melting temperature for Ptx, blank S-SEDDS, physical mixture of Ptx/blank S-SEDDS, and Ptx-loaded S-SEDDS was determined by DSC 2920. Samples were scanned from 30 to 250 °C at a rate of 10 °C /min. In all the cases, an empty pan was used as the reference. XRD patterns of Ptx, blank S-SEDDS, physical mixture of Ptx/blank S-SEDDS and Ptx-loaded S-SEDDS were recorded using an X'Pert PRO Multipurpose X-Ray diffractometer equipped with CuKα radiation (40 kV, 20 mA). The 2θ scanning range was varied from 2° to 50°.
We thank the University of Oklahoma and the chemistry faculty for providing the space, instructions, and equipment for the development of this report and experiment.
The X-ray was first discovered in 1895 by a German physicist named W.C. Roentgen (“The Discovery”). W.C. Roentgen was working in his lab one day in 1895 and decided to send a high electrical current through a cathode ray filled with special gas. He realized that a dim green colored light was being produced, and decided to hold the cathode ray just above his wife’s hand. When he did this he observed that the light was able to penetrate human skin, but would leave all the bones visible. There is a picture below of the X-ray of W.C. Roentgen’s wife’s hand (“The Discovery”). He named it the X-ray because he did not know the identity of what kind of ray it was. He just named it X, because of its use in solving unknowns in algebraic equations (“The Discovery”).
Scanning electron microscopy (SEM) technique was employed extensively through want this study to examine and obtain images of prepared samples. The associated analytical facility of Energy dispersive X-Ray (EDX) analysis was used to identify and quantify the elemental composition of the prepare samples.
In order to understand the controversy of fluoride, one must know the background . Fluoride is the ionic form of the element fluorine, an element abundant in the earth's crust (Borso 23). Fluoride is shown that is
This specific lab will focus on the two main variants of Atomic Absorption Spectroscopy: flame AA spectroscopy, and spectroscopy using a graphite furnace. The lab will also introduce and teach how to deal with both systematic and random error when using Atomic Absorption Spectroscopy.
For decades, the effects of radiation has been studied by doctors around the world. X-rays are used in the medical and dental field to take radiographs of certain parts of a person's body. Some have become concerned of the long term and short term effects of having x-rays taken because of the radiation that is exposed. Since the rise of concern, studies have been done to find any type of link between cancer and radiation from x-rays. Specifically, in dental x-rays, researchers have been performing studies trying to prove that radiation from x-rays in the dental office can cause cancer .
How does the X-ray work? Well first off let me tell you the difference of light rays and X-rays. The light rays are visible light waves and x-rays is a light that is smaller than atoms in your body. You can’t see them with the naked eye like sun rays. X-rays will only pick up items and body parts that are hard and also made of calcium. That light will then project your muscle that would look like a light gray and your bone structure that will be white onto a black piece of radio graphic film.
In dentistry there is a need for taking an x-ray, the x-ray is a way to help the dentist diagnose a patients oral hygiene and to see if there are any other areas in the mouth that may need to have any type of work. The dentist or the assistant will want to make sure that they can get all the teeth possible in the radiograph (x-ray) as possible to reduce the amount of exposure to the patient. Most people will have exposure to radiation just from standing outside in the sun for a long period of time, which is what we call “background exposure”.
A radioisotope is an isotope that emits radiation as it has nuclear instability(Prostate Cancer; Fusion imaging helps target greater doses of radiation).Those who are not too familiar with radioisotopes may think their use is for harmful radiation, nuclear weapons, and the possibility of turning into a giant, raging, green monster. However, there are much more positive uses for radioisotopes. There have been many medical advances thanks to the benefit and practice of radioisotopes in nuclear medicine. These advances have been able to diagnose and treat a variety of diseases.
The nuclei are ejected from heavy, unstable nuclei so as to remove excess protons and neutrons. However, the formed nuclei may still be radioactive in which even further decay will occur. Alpha emissions occur in nuclei with atomic numbers greater than 83. E.g 23892U 42He + 23490Th (both mass and No. of protons are conserved during the reaction)
Individual atoms can emit and absorb radiation only at particular wavelengths equal to the changes between the energy levels in the atom. The spectrum of a given atom therefore consists of a series of emission or absorption lines. Inner atomic electrons g... ... middle of paper ... ... a sensitive multielement inorganic analyses.
Coherent Scattering is the idea of secondary radiation being released with no ionization of matter because of this is it also known as “unmodified scattering” (Curry III, 1990, p. 61). Coherent Scattering is the process of a low energy radiation as a photon exciting an electron and changing direction giving off low energy scatter radiation with the same wavelength, frequency and energy (Dufresne, personal communication, February 5, 2018). Coherent scattering has two different types Rayleigh scattering the effect of all electrons in an atom and Thomson scattering the effect of only one electron in an atom also known as classical scattering (Bushong, 2008, p. 163). Grenz radiation is soft radiation or a type of low energy radiation that is said
As x-rays exit the patient, they interact with a cesium iodide input phosphor which converts the x-ray energy into visible light. Cesium iodide crystals are a tightly packed layer of linear needles which help improve spatial resolution by allowing little light dispersion. Attached to the input phosphor is the photocathode. Bushong describes the photocathode as, “a thin metal layer usually composed of cesium and antinomy compounds that respond to stimulation of input phosphor light by the emission of electrons.” (Bushong, 2013, p. 405). This phenomenon of electron emission following light stimulation is called photoemission. The emission of just one electron through photoemission is dependent upon numerous light photons. The amount of electrons produced by the photocathode is directly proportional to how much light reaches it from the input phosphor, which is directly proportional to the intensity of the initial x-ray beam. These electrons will be accelerated to the anode where they will pass through a small hole to the output phosphor. The output phosphor, made of zinc cadmium sulfide, is where the electrons produced through photoemission will interact and produce light. It is extremely