Elastic recoil detection techniques

Depth Profiles of Thin Films and Interfaces by the Elastic Recoil Detection Technique... 

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 use of nuclear techniques allows the determination of C, N, H, O, and heavier contaminants relative fractions with great accuracy, and of the elements depth profile with moderate resolution (typically 10 nm). Rutherford backscattering spectroscopy (RBS) of light ions (like alpha particles) is used for the determination of carbon and heavier elements. Hydrogen contents are measured by forward scattering of protons by incident alpha particles (ERDA) elastic recoil detection analysis [44,47]. 

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). 

Because RBS is rather insensitive to light elements and unable to detect hydrogen, one can make use of the complementary technique Elastic Recoil Detection (ERD) when sensitivity for light elements is required. In this case, recoiled particles are detected instead of the back scattered particles. The incident beam usually consists of heavier ions, e.g. 2 Si (4He is sufficient when one is interested in H and D only), and a stopper foil prevents backscattered particles from entering the detector, whereas the lighter recoiled particles are transmitted [32]. 

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. 

Nuclear reaction analysis (NRA) and elastic recoil detection (ERD) are part of the suit of ion beam analysis (IBA) techniques. They are commonly used for the elemental depth profiling of materials in a wide range of fields, e.g., from biological and medical to the semiconductor industry. 

The most commonly used accelerator-based techniques for depth profiling are Rutherford Backscattering (RBS) which will be discussed in Chap. 2, Elastic Recoil Detection (ERD) which will be discussed in Chap. 3, and Nuclear Reaction Analysis (NRA) which will be discussed in Chap. 7. PIXE analysis has the advantage of a very good sensitivity and possible simultaneous detection of all heavier elements. 

In contrast to the RBS, the technique of detection of the recoiled (secondary) particles is called elastic recoil detection (ERD) which was first reported in 1976 by L Ecuyer et al. The ERD provides depth as well as mass information regarding the target particle location and therefore allows simultaneous profiling of all elements within the substrate. ERD is... 

In ERD A analysis, mass identification is done by means of the ToF method, i.e., the coincident measurement of energy and flight time for each recoil. Time-of-fight elastic recoil detection (ToF-ERD) is a powerful and complimentary technique to Rutherford spectrometry for elemental analysis in surface... 

Ion scattering techniques are useful for characterizing corrosion layers. ISS provides information about the outermost monolayer. ERD (elastic recoil detection) is sensitive to light elements in a heavy matrix and thus provides useful H and Li profile information. Rutherford backscattering spectrometry (RBS), on the other hand,... 

Forward recoil spectrometry (FRES, FReS or FRS), which is also referred to as elastic recoil detection analysis (ERDA or ERD), is a member of a family of techniques collectively termed ion beam analysis (IBA). FRES is a powerful, standard-free absolute method for the measurement of atomic composition and impurity concentrations in the near-surface region of solids, and is considered a fully non-invasive technique. However, in the case of polymeric materials this assumption is not entirely true, since the projectile ions cause a breaking of covalent bonds (vide infra). The method is based on scattering of an incident accelerated-ion beam by the sample, due to nuclear and electrostatic interactions. The collision of the ions with the specimen results - in addition to scattered incident ions - in the ejection of photons, ions, or nuclear decay products, as shown schematically in Figure 23.28 [110]. 

Elastic recoil detection (ERD) >10 flat, >1 cm H/D or other elements — Direct technique element specific... 

A number of papers have appeared giving a complete description of this technique which is sometimes known in the literature as elastic recoil detection (ERD). The discussion presented here will therefore be brief. FRES is used to determine the volume fraction versus depth profile of a species labelled by deuteration which was allowed to diffuse into an unlabelled host. The diffusion coefficient is extracted from this profile using a solution to the diffusion equation. 

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