TY - JOUR
T1 - The dynamics of core hole excitation and decay in adsorbed and condensed molecules on solid surfaces
AU - Menzel, Dietrich
PY - 1995/3/31
Y1 - 1995/3/31
N2 - In isolated molecules, the decay of neutral and ionic core-excited species leads to distinctly different decay electron spectra which are usually termed autoionization and Auger spectra, respectively. If a molecule is coupled to a substrate in an adsorbate state, or to other surrounding species in a condensed phase, this coupling can modify or, in the extreme, eliminate this difference; also, satellite structure can be influenced. This results from charge and/or energy transfer between the target molecule and its surroundings before the decay event, and can therefore be used to obtain information about such processes on time scales on the order of the core hole life time or shorter. Additional information can be derived from the registration of fragmentation of the molecule as a consequence of the primary excitation and/or the final states of decay. In this case, a third time scale, that of motion of atoms or groups of atoms, comes into play which in extreme cases can compete with those of hole decay and electronic coupling to the surroundings. Such coupling to nuclear motion is also at work in the interference of the electronic evolution with vibrational motion in the molecule which can be investigated with sufficient resolution in the primary excitation. Again, the change induced here into the behavior of the free molecule by the presence of a coupled medium (substrate or condensate) can be used to extract information on the relative time scales. At present much of this information is of a qualitative nature; adequate theories would be very helpful for more detailed understanding.
AB - In isolated molecules, the decay of neutral and ionic core-excited species leads to distinctly different decay electron spectra which are usually termed autoionization and Auger spectra, respectively. If a molecule is coupled to a substrate in an adsorbate state, or to other surrounding species in a condensed phase, this coupling can modify or, in the extreme, eliminate this difference; also, satellite structure can be influenced. This results from charge and/or energy transfer between the target molecule and its surroundings before the decay event, and can therefore be used to obtain information about such processes on time scales on the order of the core hole life time or shorter. Additional information can be derived from the registration of fragmentation of the molecule as a consequence of the primary excitation and/or the final states of decay. In this case, a third time scale, that of motion of atoms or groups of atoms, comes into play which in extreme cases can compete with those of hole decay and electronic coupling to the surroundings. Such coupling to nuclear motion is also at work in the interference of the electronic evolution with vibrational motion in the molecule which can be investigated with sufficient resolution in the primary excitation. Again, the change induced here into the behavior of the free molecule by the presence of a coupled medium (substrate or condensate) can be used to extract information on the relative time scales. At present much of this information is of a qualitative nature; adequate theories would be very helpful for more detailed understanding.
UR - http://www.scopus.com/inward/record.url?scp=8944249631&partnerID=8YFLogxK
U2 - 10.1016/0368-2048(94)02296-8
DO - 10.1016/0368-2048(94)02296-8
M3 - Article
AN - SCOPUS:8944249631
SN - 0368-2048
VL - 72
SP - 19
EP - 29
JO - Journal of Electron Spectroscopy and Related Phenomena
JF - Journal of Electron Spectroscopy and Related Phenomena
IS - C
ER -