Related Experiment Video
Updated: Jan 4, 2026
07:41
Advanced Compositional Analysis of Nanoparticle-polymer Composites Using Direct Fluorescence Imaging
Published on: July 19, 2016
8.0K
Observation of Electron Shakeup in CdSe/CdS Core/Shell Nanoplatelets
Felipe V Antolinez1, Freddy T Rabouw1, Aurelio A Rossinelli1
1Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering , ETH Zurich , 8092 Zurich , Switzerland.
Nano Letters
|November 6, 2019
Summary
Researchers studied individual cadmium selenide/cadmium sulfide (CdSe/CdS) core/shell nanoplatelets (NPLs) at cryogenic temperatures. They discovered electron "shakeup lines" from trions cause emission line broadening in these NPLs.
Area of Science:
- Materials Science
- Quantum Dots
- Nanotechnology
Background:
- Colloidal nanoplatelets (NPLs) like CdSe exhibit narrow photoluminescence (PL) line widths at room temperature.
- Adding a CdS shell enhances fluorescence and photostability but broadens the PL line width and causes asymmetry at low temperatures.
- Understanding these broadening mechanisms is crucial for developing NPLs with improved optical properties for applications.
Purpose of the Study:
- To investigate the origin of line width broadening and spectral asymmetry in CdSe/CdS core/shell NPLs.
- To analyze the emission spectra of individual NPLs at cryogenic temperatures to understand underlying physical processes.
Main Methods:
- Time-resolved emission spectra of individual CdSe/CdS core/shell NPLs were measured at 4 K.
- Machine-learning algorithms were employed to analyze complex spectral features and identify peak energy differences.
- Time-resolved single-photon counting and numerical calculations were used to study spectral dynamics.
Main Results:
- Complex emission spectra with multiple, narrow features that evolve over time were observed.
- Characteristic peak energy differences were identified and attributed to electron 'shakeup lines' from negatively charged trions.
- Spectral jumps were linked to fluctuations in the confinement potential caused by surface structural changes.
Conclusions:
- Electron shakeup from trions, enabled by strong exciton binding and weak lateral confinement, is a key mechanism for line width broadening in CdSe/CdS NPLs.
- Microscopic surface changes, such as mobile charges, contribute to spectral dynamics and broadening.
- These findings offer critical insights into the factors governing optical properties of core/shell NPLs.
Related Concept Videos
01:27π Electron Effects on Chemical Shift: Overview
1.5K
An applied magnetic field causes loosely bound π-electrons in organic molecules to circulate, producing a local or induced diamagnetic field over a large spatial volume. As the molecules tumble in solution, the field generated by π-electrons in spherical substituents results in a zero net field. However, the net field generated by π-electrons in non-spherical substituents is not zero. The effect of this induced field depends on the orientation of the molecule with respect to B0,...
1.5K
02:46Electron Configurations
24.9K
Electron configurations and orbital diagrams can be determined by applying the Aufbau principle (each added electron occupies the subshell of lowest energy available), Pauli exclusion principle (no two electrons can have the same set of four quantum numbers), and Hund’s rule of maximum multiplicity (whenever possible, electrons retain unpaired spins in degenerate orbitals).
The relative energies of the subshells determine the order in which atomic orbitals are filled (1s, 2s, 2p, 3s, 3p,...
The relative energies of the subshells determine the order in which atomic orbitals are filled (1s, 2s, 2p, 3s, 3p,...
24.9K
01:14π Electron Effects on Chemical Shift: Aromatic and Antiaromatic Compounds
1.7K
In aromatic compounds, such as benzene, the circulation of (4n + 2) π-electrons sets up a diamagnetic or diatropic ring current around the perimeter of the molecule. This current induces a magnetic field that opposes the external field inside the ring and reinforces it on the outside. The protons in benzene are deshielded and exhibit high chemical shifts in the range 6.5–8.5 ppm. The shielding effect at the center of the ring is evident in complex aromatic molecules, such as...
1.7K
03:26Electron Configuration of Multielectron Atoms
63.9K
The alkali metal sodium (atomic number 11) has one more electron than the neon atom. This electron must go into the lowest-energy subshell available, the 3s orbital, giving a 1s22s22p63s1 configuration. The electrons occupying the outermost shell orbital(s) (highest value of n) are called valence electrons, and those occupying the inner shell orbitals are called core electrons. Since the core electron shells correspond to noble gas electron configurations, we can abbreviate electron...
63.9K
01:07Scanning Electron Microscopy
5.2K
A scanning electron microscope (SEM) is used to study the surface features of a sample by using an electron beam that scans the sample surface in a two-dimensional manner. Typically, areas between ~1 centimeter to 5 micrometers in width can be imaged. SEM can be used to image bacteria, viruses, tissues as well as larger samples like insects. Conventional SEM gives a magnification ranging from 20X to 30,000X and spatial resolution of 50 to 100 nanometers.
Fundamental Principles
Accelerated...
Fundamental Principles
Accelerated...
5.2K
01:09Electron Behavior
11.2K
Electrons are negatively charged subatomic particles attracted to and orbit around the positively-charged nucleus of an atom. They reside in spaces associated with energy levels called shells and are further organized into subshells and orbitals within each shell.
Electrons Orbit the Nucleus
Electrons are found in specific locations outside of the nucleus. The shell in which an electron resides indicates the general energy level of the electron: those closer to the nucleus have less energy,...
Electrons Orbit the Nucleus
Electrons are found in specific locations outside of the nucleus. The shell in which an electron resides indicates the general energy level of the electron: those closer to the nucleus have less energy,...
11.2K