Cresting the Coulomb Barrier of Polyanionic Metal Clusters
F Martinez1, N Iwe1, M Müller1,2
1Institute of Physics, University of Rostock, 18059 Rostock, Germany.
Physical Review Letters
|April 16, 2021
Summary
Researchers characterized the Coulomb barrier of negatively charged silver clusters using laser excitation and photoelectron spectroscopy. This study provides the first experimental potential energy functions for these complex polyanionic metal clusters.
Area of Science:
- Atomic and Molecular Physics
- Physical Chemistry
- Materials Science
Background:
- Multiply negatively charged metal clusters are complex systems with poorly understood electron dynamics.
- Characterizing the Coulomb barrier is crucial for understanding electron emission and stability.
Purpose of the Study:
- To experimentally determine the Coulomb barrier potential of multiply negatively charged silver clusters.
- To investigate the role of electron tunneling in photoemission from these systems.
- To derive the first experimentally based potential energy functions for polyanionic metal clusters.
Main Methods:
- Utilizing tunable laser pulse excitation combined with photoelectron spectroscopy.
- Analyzing mass- and charge-selected polyanionic silver clusters (z=2-5 excess electrons).
- Parametrizing electron yield with respect to tunneling near the photoemission threshold for an 800-atom system.
Main Results:
- Observed a characteristic dependence of photoelectron spectra on excitation energy, highlighting electron tunneling.
- Successfully parametrized electron yield near the photoemission threshold.
- Derived novel, experimentally validated potential energy functions for polyanionic metal clusters.
Conclusions:
- The study successfully characterized the Coulomb barrier potential of multiply negatively charged silver clusters.
- Electron tunneling plays a significant role in the photoemission process.
- The derived potential energy functions offer new insights into the behavior of polyanionic metal clusters.
Related Concept Videos
02:58Crystal Field Theory - Octahedral Complexes
28.7K
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
28.7K
01:24Metal-Semiconductor Junctions
625
The contact of metal and semiconductor can lead to the formation of a junction with either Schottky or Ohmic behavior.
Schottky Barriers
Schottky barriers arise when a metal with a work function (Φm) contacts a semiconductor with a different work function (Φs). Initially, electrons transfer until the Fermi levels of the metal and semiconductor align at equilibrium. For instance, if Φm > Φs, the semiconductor Fermi level is higher than the metal's before contact. The...
Schottky Barriers
Schottky barriers arise when a metal with a work function (Φm) contacts a semiconductor with a different work function (Φs). Initially, electrons transfer until the Fermi levels of the metal and semiconductor align at equilibrium. For instance, if Φm > Φs, the semiconductor Fermi level is higher than the metal's before contact. The...
625
03:45Formation of Complex Ions
24.8K
A type of Lewis acid-base chemistry involves the formation of a complex ion (or a coordination complex) comprising a central atom, typically a transition metal cation, surrounded by ions or molecules called ligands. These ligands can be neutral molecules like H2O or NH3, or ions such as CN− or OH−. Often, the ligands act as Lewis bases, donating a pair of electrons to the central atom. These types of Lewis acid-base reactions are examples of a broad subdiscipline called coordination...
24.8K
02:51Metal-Ligand Bonds
22.6K
The hemoglobin in the blood, the chlorophyll in green plants, vitamin B-12, and the catalyst used in the manufacture of polyethylene all contain coordination compounds. Ions of the metals, especially the transition metals, are likely to form complexes.
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
22.6K
00:56Extraction: Advanced Methods
742
Metal ions can be separated from one another by complexation with organic ligands–the chelating agent– to form uncharged chelates. Here, the chelating agent must contain hydrophobic groups and behave as a weak acid, losing a proton to bind with the metal. Since most organic ligands used in this process are insoluble or undergo oxidation in the aqueous phase, the chelating agent is initially added to the organic phase and extracted into the aqueous phase. The metal-ligand complex is...
742
01:19Complexation Equilibria: The Chelate Effect
825
In complexation reactions, metal atoms or cations interact with ligands to form donor-acceptor adducts called metal complexes. Ligands that bind through one donor site are monodentate, ligands with two donor sites are bidentate, and those with more than two donor sites are polydentate ligands. For example, ethylene diamine is a bidentate ligand that binds through two nitrogen donor atoms, forming a five-membered ring. EDTA is a polydentate ligand that binds through four oxygen and two nitrogen...
825