Elastic recoil detection
Encyclopedia
Elastic Recoil Detection, also referred to as forward recoil scattering, is a nuclear
technique in materials science
to obtain elemental concentration depth profiles in thin films. An energetic ion
beam is directed at the sample to be depth profiled and (as in Rutherford backscattering) there is an elastic
nuclear interaction with the atoms of the sample. The incident energetic ions typically have MeV
of energy
, enough to kick out (recoil) the atoms being struck. The technique depends on putting in an appropriate detector to detect these recoiled atoms.
The great advantage in ERD is that all the atoms of the sample can be recoiled if a heavy incident beam is used, so a complete analysis of the sample is immediately available. For example, a 200MeV Au beam can be used with a gas ionisation detector. With the right recoil angle the scattered incident beam is kinematically
prohibited, and therefore does not enter the detector. Alternatively, a 35 MeV Cl
(or 50MeV I
) beam is often used with a time-of-flight detector: this is good for light elements (or transition metals) in silicon.
ERD is also often done using a relatively low energy (2MeV) 4He beam specifically to depth profile hydrogen. In this technique multiple detectors are used, at backscattering angles to detect heavier elements by RBS and a forward (recoil) detector to simultaneously detect the recoiled hydrogen. The recoil detector has to have a "range foil": a thin film (typically 6 micrometres of PET film
) to preferentially stop the incident He beam scattered into the forward direction.
ERDA = Elastic Recoil Detection Analysis
FRS = Forward Recoil Scattering
HFS = Hydrogen Forward Scattering
Nuclear physics
Nuclear physics is the field of physics that studies the building blocks and interactions of atomic nuclei. The most commonly known applications of nuclear physics are nuclear power generation and nuclear weapons technology, but the research has provided application in many fields, including those...
technique in materials science
Materials science
Materials science is an interdisciplinary field applying the properties of matter to various areas of science and engineering. This scientific field investigates the relationship between the structure of materials at atomic or molecular scales and their macroscopic properties. It incorporates...
to obtain elemental concentration depth profiles in thin films. An energetic ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...
beam is directed at the sample to be depth profiled and (as in Rutherford backscattering) there is an elastic
Elastic collision
An elastic collision is an encounter between two bodies in which the total kinetic energy of the two bodies after the encounter is equal to their total kinetic energy before the encounter...
nuclear interaction with the atoms of the sample. The incident energetic ions typically have MeV
MEV
MeV and meV are multiples and submultiples of the electron volt unit referring to 1,000,000 eV and 0.001 eV, respectively.Mev or MEV may refer to:In entertainment:* Musica Elettronica Viva, an Italian musical group...
of energy
Energy
In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...
, enough to kick out (recoil) the atoms being struck. The technique depends on putting in an appropriate detector to detect these recoiled atoms.
The great advantage in ERD is that all the atoms of the sample can be recoiled if a heavy incident beam is used, so a complete analysis of the sample is immediately available. For example, a 200MeV Au beam can be used with a gas ionisation detector. With the right recoil angle the scattered incident beam is kinematically
Kinematics
Kinematics is the branch of classical mechanics that describes the motion of bodies and systems without consideration of the forces that cause the motion....
prohibited, and therefore does not enter the detector. Alternatively, a 35 MeV Cl
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...
(or 50MeV I
Iodine
Iodine is a chemical element with the symbol I and atomic number 53. The name is pronounced , , or . The name is from the , meaning violet or purple, due to the color of elemental iodine vapor....
) beam is often used with a time-of-flight detector: this is good for light elements (or transition metals) in silicon.
ERD is also often done using a relatively low energy (2MeV) 4He beam specifically to depth profile hydrogen. In this technique multiple detectors are used, at backscattering angles to detect heavier elements by RBS and a forward (recoil) detector to simultaneously detect the recoiled hydrogen. The recoil detector has to have a "range foil": a thin film (typically 6 micrometres of PET film
PET film (biaxially oriented)
BoPET is a polyester film made from stretched polyethylene terephthalate and is used for its high tensile strength, chemical and dimensional stability, transparency, reflectivity, gas and aroma barrier properties and electrical insulation.A variety of companies manufacture boPET and other...
) to preferentially stop the incident He beam scattered into the forward direction.
Synonyms and acronyms
ERD = Elastic Recoil DetectionERDA = Elastic Recoil Detection Analysis
FRS = Forward Recoil Scattering
HFS = Hydrogen Forward Scattering