Quantum confinement :
Quantum dots are extremely small semiconductors , they can be imagined as particles in a ‘box’ (quantum dot) . As the size of the ‘box’ decreases the electrons will be condensed leading to quantum confinement . In this state the particle will have a specific energy level and is said to be quantized . A particles specific energy level is inversely proportionate to it’s wavelength . The quantum confinement of a particle leads to a blue shift , i.e. A decrease in wavelength . In visible light, this shifts the color from the red end of the spectrum to the blue end .
In short this means that a nanocrystal can be tuned to absorb a specific EM frequency & further emit a specific frequency , dependent on its size & structure .
In addition nanocrystals can be ‘tuned’ in real time by applying an external electromagnetic wave , meaning that the crystal is able to absorb & emit differing EM wavelengths . This is known as the Quantum-confined Stark effect , such crystals are termed tunable nanomaterials . Tunable nanomaterials were first developed for the aerospace & defence industries .
Furthemore , nanocrystals can be layered , thus enabling the synchronous absorption & emmission of a broad spectrum of different EM wavelengths .
Quantum dots are currently forging a new frontier in computing & AI .
Metal Oxide Nanocrystals :
Metal oxide nanocrystals display a wide variety of complex structures and exhibit complex optical , electronic and magnetic properties , this is dependent on the structure & composition of the crystal . Rare earth metal oxides are commonly used , this is due to the unique optical & magnetic properties of rare earth metals . Apart from opium , Taliban fighters & U.S. troops , Afghanistan has one of the largest deposits of rare earth metals .
- Nanocrystals can be formed in a variety of shapes including dot, sphere, cube, rod & hexagon .
- Nanocrystals can be designed to bind to specific cell receptors in the human body .
- Magnetic nanocrystals can be formed which are activated with an applied electromagnetic wavelength .
- Magnetic nanoparticles can be synthesized using several methods including chemical reactions , thermal decomposition & microwave / laser application .
- Metal oxide nanocrystals can be formed which absord & emit specific frequencies from the electromagnetic spectrum .
- Certain rare earth oxide nanocrystals display strong magneto-optic properties . Also known as Faraday rotation this phenomenon describes the interaction of light & magnetic fields . Faraday rotation can be used to enhance & measure weak electrical currents in molecules & optical fibres . Applications include biological imaging & biological sensing .
- Quantum dot nanocrystals are also used in brain mapping applications & neuro science .
- Nano crystals can be cultured from an initial nuclei containing the crystal atoms using a process called nucleation .
- Nanocrystals can be transported to the host via a carbon nanotube or nanofibres which house a payload containing the initial nuclei material .
- Nanocrystals can be formed synthetically using a variety of methods to control the size & structure .
- A common method for controlling the growth of nanocrystals is to use ligands also known as surfactants (surface active agents) . These organic compounds inhibit the growth of the nanocrystal and are also known as capping agents .
- Chemical stabilizers can also be used to halt crystal expansion .
- Surfactants can also be used to shape the crystal , encouraging or inhibiting growth across a certain plane .
- Nanocrystals can also be combined to form larger lattice type structures .
Quantum Dot Nanocrystals :
- Hybrid nanomaterials design synthesis and biomedical applications
- Quantum Dots (PDF)
- Nano: Quantum dots & Carbon Nanomaterials & Magnetic Nanomaterials
- Quantum confinement effect – an overview (PDF)
- Application of Quantum Dots in Biological Imaging
- Qdot Nanocrystals
- Team demonstrates quantum dots that assemble themselves
- Graphene-DNA biosensor selective, simple to create
Also related :
Monodisperse Metal Oxide Nanocrystals :
- Size and Shape Controlled Synthesis of Monodisperse Metal Oxide and Mixed Oxide Nanocrystals
- Magnetic nanoparticles: synthesis, functionalization, and applications in bioimaging
- A cheap and facile route to synthesize monodisperse magnetic nanocrystals and their application as MRI agents
- Magnetic Fluorescent Delivery Vehicle Using Uniform Mesoporous Silica Spheres Embedded with Monodisperse Magnetic and Semiconductor Nanocrystals
- Synthesis, characterization and magnetic properties of Hexagonal CuCr2Se4 nanoparticles
- Magnetic Nanoparticles
- Magnetic nanoparticles (Wikipedia)
Further related :
Phase Conjugation :
- Selective erasure for multiplexed holograms in photorefractive crystal using phase conjugate mirror
- Optical phase conjugation
- An Intuitive Explanation of Phase Conjugation
- Tuning Phase Stability of Complex Oxide Nanocrystals via Conjugation
- Conjugation of DNA to Silanized Colloidal Semiconductor Nanocrystalline Quantum Dots
- Optical Phase Conjugation and Its Applications in Biology
- Electromagnetic equivalent model for phase conjugate mirror based on the utilization of left-handed material (PDF)