Radiationless transition. Auger process

The competitive relaxation process known as the Auger effect involves radiationless transitions and the ejection of valency electrons. X-ray fluorescence spectrometry has developed as a... 

In this case, an M electron is emitted as an Auger electron. The Auger process is termed a radiationless transition. The probability that an inner shell vacancy... 

This is termed a radiationless transition, and the emitted electron is called an Auger electron. Figure 5.1 shows a schematic diagram of the X-ray emission and Auger processes. 

Figure 5.7 Spectrum of electrons ejected from magnesium atoms after interaction with 80 eV photons (measured at the quasi-magic angle in order to allow the extraction of relative intensities). The 3s and 2p photolines are shown together with their satellites and the radiationless transitions following the 2p main and satellite processes, i.e., L2 3-M,M1 normal Auger transitions and Auger satellites, respectively. From [HKK88].

Capture may take place to bound states of the negative ion that undergo radiationless transitions to repulsive states of the negative ion resulting in dissociative electron capture. These radiationless intramolecular transitions (Auger transitions) are a result of overlap of the discrete states with a continuum of states of AB-. These types of processes are illustrated for diatomic molecules in Figure 2.2b. Electrons are first captured into the bound state represented by curve 1, and before autodetachment can take place an intramolecular radiationless transition occurs to curve 2 resulting in dissociation into A and B-. 

Both autoionisation and the Auger effect are often referred to as radiationless transitions, because the initial reorganisation of the atom, takes place on very short timescales (typically 10 13s) without the emission of radiation. This does not, however, mean that no radiation at all is emitted by the atom during or after either of these processes. It is merely that... 

Auger spectroscopy prepares a system in a core-hole state by ionizing radiation and measures the kinetic energy of secondary electrons produced when the highly excited core-hole state makes a radiationless transition to a continuum state with two valence-holes and a free electron. The initial photoelectron and the secondary (Auger) electron make this a two-electron detachment process leading to the two-particle two-hole propagator... 

The probability amplitude for the radiationless transition of the Auger process then is... 

For X = K (no subshell) the number of X-ray photons emitted is given by Nk=N(Dk where N is the total number of K holes involved. Here N is equal to the sum of radiative and radiationless transitions. To a first approximation, K radiationless transition probability is nearly independent of Z, while radiative electric-dipole probability is proportional to Z. It justifies useful semiempirical laws based on q)kOcZ /(Z +c), c=constant. They are discussed in [4] which also gives many references on Auger and related processes up to 1971. Due to Coster-Kronig transitions, experimental and theoretical problems are more complicated for X = L, M,. .. Experimental data depend on the primary vacancy distribution which must remain unaltered before the vacancies are filled. Literature provides either total X-shell data(X = L, M,. ..) or partial Xj-subshelldata (Xj = L., Lg, L3,. ..). Definitions... 

Auger electron) from the atom. This is a radiationless process leading to double ionization. A transition of an electron from an L shell to a K shell vacancy, accompanied by the ejection of an L shell electron, is represented as a KLL transition. The energy of the ejected electron in KLL transition is Auger- LL Here is the energy of the atom... 

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