Elastic Recoil Spectrometry, ERS

Elastic recoil spectrometry (ERS) is used for the specific detection of hydrogen ( H, H) in surface layers of thickness up to approximately 1 pm, and the determination of the concentration profile for each species as a function of depth below the sample s surfece. When carefully used, the technique is nondestructive, absolute, fast, and independent of the host matrix and its chemical bonding structure. Although it requires an accelerator source of MeV helium ions, the instrumentation is simple and the data interpretation is straightforward. 

Typically, ERS measurements are run with 1-2 MeV He ions, where such problems do not arise. 

The energy scale of an elastic recoil spectrum provides information about the mass of the recoiling species, and about the depth within a sample at which the scattering took place. 

M2 is the mass of the recoiling ion 2 is the energy of the recoiling particle at the point of the collision. 

For the simple case of surface scattering (or scattering from a very thin layer), the ratio of to is given by 

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