Detection techniques recoil atoms

The amount of Es available at this time was very small about N = 10 atoms (a 4- 10 g). At a flux density of a particles = 10 " cm s , a cross section (Ta n = 1 mb and an irradiation time of 10 s a yield N

single atoms, the recoil technique was applied (Fig. 14.6). Es was electrolytically deposited on a thin gold foil. The recoiling atoms of Md were sampled on a catcher foil. After irradiation, the catcher foil was dissolved and Md was separated on a cation-exchange resin. In 8 experiments 17 atoms of Md were detected and identified by their transmutation into the spontaneously fissioning the properties of which were known ... 

ERGS (elastic recoil coincidence spectrometry) is a variation of transmission ERDA. Two detectors are used, one to detect the scattered incident particle and the other to detect the recoiled target atom. This technique is very suited to the study of polymers, which can be easily made as thin self-supporting films. 

The particle identif3dng detection techniques are used to separate the forward scattered ions and recoils from the target with respect to their energy and atomic number/mass by one of the detection systems mentioned Sect. 3.4.1. 

The most common mode of chemical analysis presented herein has been the monitoring of elastically/inelastically scattered or recoiled incident beam species, or the analysis of a secondary emission pattern. In addition to the release of characteristic X-rays, Auger electrons, and photoelectrons, an incident beam may cause ionization of the sample. This technique is known as secondary-ion mass spectrometry (SIMS), which represents the most sensitive surface characterization technique developed to date, with detection limits of atoms cm ... 

Forward recoil spectrometry (FRS) [33], also known as elastic recoil detection analysis (ERDA), is fiindamentally the same as RBS with the incident ion hitting the nucleus of one of the atoms in the sample in an elastic collision. In this case, however, the recoiling nucleus is detected, not the scattered incident ion. RBS and FRS are near-perfect complementary teclmiques, with RBS sensitive to high-Z elements, especially in the presence of low-Z elements. In contrast, FRS is sensitive to light elements and is used routinely in the detection of Ft at sensitivities not attainable with other techniques [M]- As the teclmique is also based on an incoming ion that is slowed down on its inward path and an outgoing nucleus that is slowed down in a similar fashion, depth infonuation is obtained for the elements detected. 

The major role of TOF-SARS and SARIS is as surface structure analysis techniques which are capable of probing the positions of all elements with an accuracy of <0.1 A. They are sensitive to short-range order, i.e. individual interatomic spacings that are <10 A. They provide a direct measure of the interatomic distances in the first and subsurface layers and a measure of surface periodicity in real space. One of its most important applications is the direct determination of hydrogen adsorption sites by recoiling spectrometry [12, H]. Most other surface structure techniques do not detect hydrogen, with the possible exception of He atom scattering and vibrational spectroscopy. 

IBA techniques, which also include Rutherford backscattering spectrometry (RBS) and particle induced X-ray emission (PIXE), require the use of a particle accelerator to produce a beam of mono-energetic MeV ions which is then incident on a target. The ions may interact with atomic electrons within the target to produce characteristic X-rays or they may collide with nuclei. If an ion collides with a nucleus it may scatter, cause the nucleus to be ejected (recoiled) or undergo a nuclear reaction resulting in the emission of particles and/or y-rays. NRA involves the detection of particles or y-rays caused by nuclear reactions in the target while ERD involves the... 

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