 |
 |
|
 |
|
 |
|
 |
|
 |
Core
Level Spectroscopies
Core level spectroscopy provides
a method to study the chemical state, local geometric structure,
nature of chemical bonding, and dynamics in electron transfer
processes centered around one atomic site. 
The ejection of a core electron is initiated by the absorption of an x-ray
photon with energy tuned to the electron's ionization energy shown here.
The resulting excitations and relaxations form the basis for the various
core level spectroscopies, shown schematically below.
Scroll down to see:
Creation of
Core Holes
Decay of Core
Holes
<
/font>Resonant Processes
Schematic
view of the local probing character of core level spectroscopies a
pplied
to N2 adsorbed
on Ni. The grey area represents
the charge density outside the metal surface with a cut into the molecular
adsorbate. Electronic transitions between the core and valence electrons
are indicated with arrows.
Core holes are create
d
through core-level ionization and x-ray absorption processes and the core hole decays
by radiant and non-radiant processes.
The different techniques can be separated into two classes, creation and
decay of core-holes. We can create a core-hole through the absorption
of incoming light. The core electron can be excited to a bound state or
to the continuum where it will become a free particle.
This forms the basis for X-ray photoelectron spectroscopy,
X-ray absorption spectroscopy, Auger electron
spectroscopy, and X-ray emission spectroscopy.
These techniques
are presented in terms of schematic pictures of the core ele
ctrons and
the electronic structure in a metal in terms of occupied and unoccupied
valence states divided by a Fermi level.
|
|||||||||||||
Decay of Core Holes
|
||||||
These events only consider a core-ionized
initial state prior to the decay. However, an initial state with the core
electron instead excited
into a bound state can modify the decay process.
The two steps, creation and decay, can lead to coupling and the whole
process can be considered a one step event. These events are called resonant processes and can involve
radiant and non-radiant decays. The excited electron can either participate
in the decay proc
ess or be passive as a spectator leading to very different
types of final states.
|
Non-Radiant
Resonant Photoelectron Spectroscopy (RPES) Resonant Auger Spectroscopy (RAES) Autoionization Spectroscopy (AIS) |
Radiant
Resonant Inelastic X-ray Scattering (RIXS) Resonant X-ray Emission Spectroscopy (RXES) |
<
/tr>
||
 |
 |
||
| Participator
decay one hole final state |
|
|
|
