Elastic Recoil Detection Analysis ERDA

In reflection ERDA the ion beam impinges on to the specimen at grazing incidence, and the recoils emerge from the front surface, generally also at a grazing angle. 

Tirira et al. (1996) give a detailed account of both the theory and application of the technique to the determination of hydrogen in solids, to which reference may be made by the interested reader. 

From a specimen surface of typical area 5x15 mm2, ERDA may thus provide a non-destructive determination of hydrogen isotopes and their depth profiles in polymers and other solids with a sensitivity of 0.01 atomic %, a depth resolution of about 10 nm close to the surface, but decreasing with increasing depth. The maximum depth of analysis is about 1 pm (depending on the material). Measurements of other light elements (Z 9) are also possible if heavy ions such as Cl or Au are used. 

The TOF energy telescope consists of two channel-plate timing detectors followed by a silicon energy detector. A simple short TOF spectrometer is also 

like RBS, is based on the following physical concepts  

In ERDA, different regimes have been developed with a broad range of projectiles and energies, which can roughly be separated into three groups  

The sensitivity and depth resolution of ERDA depend on the type of projectile, on the type of particle, and on energy measurement. Because of the broad range of particles and methods used, general statements about sensitivity and depth resolution are hardly possible. Recent reviews of ERDA techniques are available [3.152-3.154]. 

When a projectile of mass Mi, energy Ei, and atomic number Zi collides with a target atom of mass and atomic number Z2, it will transfer energy E2 to the target atom at a recoil angle 6, which is given by  

The projectiles which are also scattered with scattering angle 6 will have energy  

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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. 

Because the cross-sections for nuclear reaction are usually lower than the cross-sections for elastic scattering of projectiles used in RBS or in elastic recoil detection analysis (ERDA), higher currents must be used to obtain comparably high intensity in... 

This technique is known by a host of terms. As well as ERD, one sees it referred to as "forward scattering analysis, Forward Recoil Elastic Scattering (FRES) and Elastic Recoil Detection Analysis (ERDA). 

Elastic recoil detection analysis (ERDA) is specifically used for the determination of hydrogen profile in samples. The incident beam is composed of He ions [9],... 

Sweeney R. J., Prozesky V. M., and Springhorn K. A. (1997) Use of the elastic recoil detection analysis (ERDA) microbeam technique for the quantitative determination of hydrogen in materials and hydrogen partitioning between olivine and melt at high pressures. Geochim. Cosmochim. Acte 61, 101-113. 

Adsorption of ethylene and acetylene on platinum in the presence of hydrogen was investigated using elastic recoil detection analysis (ERDA). Below 200 K no change was observed for acetylene, while at room temperature C2H3 radicals were formed The geometry of acetylene adsorbed on the Ni (100) face was determined by LEED (low energy electron diffraction) intensity analysis. ... 

The nuclear reaction methods are suitable for the determination of several isotopes from to S. The most frequently used reactions are (p, ), (d,p) and (d,a) providing useful alternative methods for the determination of isotopes such as D, and compared with RBS or elastic recoil detection analysis (ERDA). Alpha induced reactions have a limited use. Some Li induced reactions have been tested and the ( B, a) reaction has been used for hydrogen determination and profiling. Cross-sections of 10 to 100 mb sr are observed for proton and deu-teron induced reactions with light isotopes such as D, li. Be and B. Detection limits of the order of 10 jjg g or even less are then possible with measuring times of the order of tens of minutes. Isotopes up to S can be determined in heavier matrices at mg g levels depending on the maximum beam current that the sample can withstand. 

Equation (2) is the basis for the elastic recoil detection analysis (ERDA) methods using heavy ions in the MeV region. 

X-ray emission (PIXE), heavy ion-induced X-ray emission (HIXE), particle-induced y-ray emission (PIGE), Rutherford backscattering spectrometry (RBS), and elastic recoil detection analysis (ERDA). These methods are also multielemental and nondestructive. In general, when ion beam methods are used it should be kept in mind that sulfur-containing matter may be lost during the irradiation, and therefore sufficiently low beam currents should be employed. Also, sample homogeneity is vital since the volume probed by the ions is rather small. 

Elastic recoil detection analysis (ERDA) of a pyrex-glass sample has been carried out by Grigull et al. (1997) in the elemental range of Z = 5 — 20 using element dispersive ionization chambers and a time-of-flight (ToF-E) system. 

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