Plasmonic Lasers and Spasers Analysis

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary function of silica in the context of plasmonic lasers?

Providing the optical gain for the laser

Creating spatial confinement for e-h pairs

Enhancing the laser beam wavelength

Blocking the core surface without interfering in redox reactions (correct)

What role do the organic dye molecules play in the laser structure developed by Noginov and colleagues?

They convert laser light to surface plasmon waves.

They stabilize the gold core.

They provide the laser's optical gain. (correct)

They enhance the width of the laser beam.

What is the emitted wavelength of the laser developed by Oulton and co-workers?

450 nm

800 nm

531 nm

489 nm (correct)

In the context of a spaser, what happens after the electron-hole pairs are created?

They relax to excitonic levels. (A) Signup and view all the answers

What is a characteristic of surface plasmon modes in comparison to optical wavelengths?

They are localized in dimensions much smaller than optical wavelengths. (B) Signup and view all the answers

What phenomenon drives the coherent emission of surface-plasmon waves in the gold core?

Transfer of energy from pumped photons to electrons (C) Signup and view all the answers

What material is used as the insulating gap in Oulton and co-workers' laser?

Magnesium fluoride (A) Signup and view all the answers

Which of the following is NOT a feature associated with the spaser mechanism?

Production of high-energy X-rays (C) Signup and view all the answers

What is a key advantage of the sol-gel process compared to other methods?

It provides low processing temperatures. (B) Signup and view all the answers

Which process allows for the production of materials with high chemical homogeneity?

Sol-Gel Process (A) Signup and view all the answers

In spray pyrolysis, what is the first step in the procedure?

Dissolution of the inorganic precursors. (A) Signup and view all the answers

Which material is NOT typically associated with the liquid infiltration process?

Fe/Mg (B) Signup and view all the answers

What causes the inhomogeneous phase-segregated materials in polymer precursor processing?

Agglomeration of ultra-fine particles (C) Signup and view all the answers

What is a notable characteristic of the sol-gel process in terms of product quality?

Less shrinkage and fewer voids than mixing methods. (B) Signup and view all the answers

What is the main purpose of using a carrier gas in the spray pyrolysis process?

To facilitate vaporization of droplets. (B) Signup and view all the answers

What is a key feature of Lanthanide Core/Shell Nanoparticles related to bio sensing?

High quantum yield (QY) of upconversion (D) Signup and view all the answers

Which of the following is a limitation of the polymer precursor process?

Can lead to agglomeration of particles. (D) Signup and view all the answers

What defines a nanocomposite?

A material consisting of two or more components, one of which is nanosized (A) Signup and view all the answers

Which effect occurs when electrons are confined to a small domain in nanomaterials?

Quantum confinement effect (C) Signup and view all the answers

What is one of the characteristics of nanocomposites?

They often consist of nanosized particles embedded in various matrices (D) Signup and view all the answers

What causes unusual properties in nanomaterials according to the small size effect?

Small particles interact differently with energy compared to larger ones (B) Signup and view all the answers

Which phases can be present in a nanocomposite?

Two phases including inorganic-inorganic, inorganic-organic, or organic-organic (C) Signup and view all the answers

Which property is enhanced due to the small size of particles in nanocomposites?

Increased gas absorption (C) Signup and view all the answers

What are the dimensional characteristics of the components in nanocomposites?

Between 1 and 100 nm for at least one component (C) Signup and view all the answers

What is the initial step in the Rapid Solidification Process (RSP)?

Melting the metal components together (A) Signup and view all the answers

Which process involves the condensation of metal nanoparticles through supersaturation of vapor?

Chemical vapor deposition (CVD) (C) Signup and view all the answers

Which material is synthesized using the Colloidal Method?

Ag/Au (B) Signup and view all the answers

During the Sol-gel process, which two solutions are prepared?

HAuCl4 and NaBH4 in mesoporous silica (B) Signup and view all the answers

What is a key advantage of using ultrasonics in the Rapid Solidification Process?

It enhances wettability between matrix and reinforcements (A) Signup and view all the answers

Which method is NOT part of the Chemical vapor deposition (CVD) process?

Preparation of micelle solutions (A) Signup and view all the answers

What role do high energy ball milling techniques play in producing nanocomposites?

They mill powders to obtain nanosized alloys (A) Signup and view all the answers

What is the last step of the Chemical Processes using the Colloidal Method?

Consolidation of the dry material (A) Signup and view all the answers

What is a key benefit of using ceramic matrix nanocomposites?

Good wear resistance and high thermal stability (D) Signup and view all the answers

Which characteristic is associated with metal matrix nanocomposites?

High strength in shear/compression processes (B) Signup and view all the answers

What phenomenon occurs due to the presence of nanoparticles in larger particles?

Formation of sub-grain structures (C) Signup and view all the answers

What does the term 'blue shift' in light-emitting diodes refer to?

An increase in energy levels and modified optoelectronic properties (A) Signup and view all the answers

What is a disadvantage of polymer matrix nanocomposites?

High gas permeability to oxygen and water vapor (C) Signup and view all the answers

Which of the following best describes the assembly characteristics of nanoparticles?

They can easily aggregate and assemble in liquid or gaseous media (C) Signup and view all the answers

What advantage do polymers provide when used in nanocomposites?

Improved biodegradability and mechanical strength (C) Signup and view all the answers

Which factor contributes to the higher gas absorption of nanomaterials?

Small particle size leading to a large specific area (D) Signup and view all the answers

What is a significant advantage of melt intercalation?

Environmentally benign (A) Signup and view all the answers

Which of the following limitations is associated with the in situ polymerization method?

Difficult control of intra gallery polymerization (D) Signup and view all the answers

What procedure is included in the process of mixing when forming nanocomposites?

Dispersion of inorganic particles (C) Signup and view all the answers

Which nanocomposite synthesis method is characterized by the use of low or no polarity polymers?

In situ intercalation (D) Signup and view all the answers

What process involves the embedding of organic groups through chemical bonds?

Sol-Gel process (D) Signup and view all the answers

Which option correctly describes an advantage of the template method?

Enables large scale production (A) Signup and view all the answers

What limitation is commonly associated with melt intercalation?

Limited applications to polyolefins (C) Signup and view all the answers

What is a key aspect of the procedure involved in in situ polymerization?

Processing with ultrasonics for dispersion (B) Signup and view all the answers

Study Notes

Nanotechnology

Nanotechnology is the creation of materials with dimensions measured in nanometers, an intermediate size between isolated molecules and bulk materials.
This unique size range changes the physical and chemical properties compared to atoms, molecules, and bulk materials.

Physical Properties of Nanoparticles

Optical Properties: Nanoparticles exhibit properties related to absorption, emission, and band gap.
Electric Properties: Conductivity and resistivity are significantly affected by size.
Magnetic Properties: Properties like magnetic field, magnetic intensity, susceptibility, retentivity, and coercivity are modified.
Thermal Properties: Thermal conductivity, melting point, and heat capacity are affected.
Mechanical Properties: Hardness, yield strength, tensile strength, ductility, and toughness are often altered.

Classification of Nanostructures

The classification of nanostructures depends on the number of dimensions falling within the nanometer range.
Bulk: Three-dimensional structures.
Quantum Well: Two-dimensional structures, confined in one direction.
Quantum Wire: One-dimensional structures, confined in two directions.
Quantum Dot: Zero-dimensional structures, confined in three directions.

Physical Properties of Nanomaterials

Size, shape (spheres, rods, platelets, etc.), composition, crystal structure (FCC, BCC, etc.), surface ligands/capping agents, and dispersion medium all influence the physical properties of nanoparticles.

Size (Nanoparticles)

Nanoparticles exhibit unique properties due to a high surface area to volume ratio.
A 100nm spherical particle has a calculated volume of 5.24 x 10⁻²² m³ and a surface area of 3.141 x 10⁻¹⁴ m².
As the surface area to volume ratio increases, the percentage of atoms at the surface increases, and surface forces become more dominant, changing material properties compared to bulk.

Surface Area to Volume Ratio

A higher surface area to volume ratio in nanoparticles leads to a greater amount of substance contacting the surrounding material.
This effect enhances catalytic activity, as a larger proportion of the material is exposed for potential reactions.
This ratio increases significantly below a 100nm particle diameter (as shown in the provided graph).

Surface Area : Volume Ratio

Nanoparticles have a significantly larger surface area to volume ratio than macroscopic particles ( >10⁷:1).
As the ratio increases, the percentage of surface atoms and surface forces become more substantial, altering material properties from those exhibited by bulk material.

Melting Point as a Function of Particle Size (Nanoparticles)

Nanoparticles generally have a lower melting point compared to their bulk counterparts.
This decrease in melting point is strongly correlated with particle size, affecting gold nanoparticles in the nanoscale region (as demonstrated by the graph).

Melting Point versus Shape

Nanoparticles can sinter (join together) at lower temperatures than expected.
Rod-shaped nanoparticles can melt and form spherical droplets if heated above a certain temperature.
Thin films are particularly susceptible to pinhole formation and de-wetting/island formation with increasing temperature.

Unique Characteristics of Nanomaterials

A substantial surface to volume ratio;
High percentage of atoms/molecules on the surface;
Surface forces are crucial;
Metal nanoparticles exhibit unique light-scattering properties and plasmon resonance;
Semiconductor nanoparticles may display confined energy states within their structure (quantum dots);
Unique chemical & physical properties; and- size similarity to many biological structures.

Optical Properties

Reduced material dimensions lead to pronounced effects on optical properties, often categorized into groups:
- Increased energy level spacing in confined systems (semiconductors)
- Surface plasmon resonance in metals.

Energy Gap of Materials

The energy gap in semiconductor materials separates the conduction and valence bands, defining their conductivity type (conductor, semiconductor, insulator).
The gap size is influenced by material properties.

Confinement Length

In semiconductors, confinement occurs if any dimension (a) is smaller than the Bohr radius.
In metals, if a dimension (a) is less than the electron's mean free path. Confinement length relates to specific dimensions of materials and their behavior.

Type of Confinement

Strong: a < a_B
Intermediate: a ~ a_B
Weak: a > a_B

Metal Nanoparticles

Different shapes and sizes of metal nanoparticles (e.g., 20nm, 100nm, 500nm) are shown in the images.

Surface Plasmon Absorption

The interaction of light with a metal nanoparticle's free electrons causes surface plasmon oscillations with a specific frequency.
These oscillations influence the optical properties of metal nanoparticles.

Optical Properties (Surface Plasmons)

Plasmons are the coherent excitation of free electrons in a metal.
The resonance frequency depends on particle size, shape, and material type, related to plasmon energy by Planck's constant.
Optical properties of metal nanoparticles are primarily driven by surface plasmon interaction with incident photons.
Gold and silver nanoparticles show plasmon frequencies within the visible range; thus, light wavelengths matching this frequency get absorbed.

Rayleigh and Mie Scattering

Rayleigh scattering: Dominant for particles much smaller than the wavelengths of light, associated with the scattering of blue light in the sky.
Mie scattering: Important when particles are comparable in size to the wavelengths, involved in scattering phenomena like haze.

Elastic Scattering

Elastic scattering: No energy change during scattering; three types of elastic scattering exist: Rayleigh scattering, Mie scattering, and nonselective scattering.

Scattering

Radiation scattering from a particle depends on size, shape, index of refraction, wavelength of radiation, and view geometry.

Rayleigh Scattering (Further Detail)

Rayleigh scattering, the scattering coefficient (σλ), which is influenced by the number of particles per square centimeter (N), the volume (V), refractive indices of the particles (μ) and medium (μ₀), and the wavelength (λ) of the radiation, is significant in remote sensing.

Mie Scattering (Further Detail)

Mie scattering, the scattering coefficient (σλ), depends on the number of particles within intervals of radius (a) and da, the scattering coefficient K(α, μ) as a function of radius and refractive index, influences multispectral imagery under hazy conditions.

Scattering Types

Rayleigh scattering: Particles much smaller than the wavelength; scattering is uniformly in all directions, and is wavelength dependent; commonly associated with the sky appearing blue.
Mie scattering: Particles comparable in size to the wavelength; scattering is nonuniform, dependent on the size of the particle.

Electromagnetic Modes

Transverse mode: electromagnetic field pattern perpendicular to the propagation direction, with the electric and magnetic fields oscillating perpendicular to the direction
Longitudinal mode: electromagnetic field pattern parallel to the propagation direction.

Mie Theory

Gustav Mie developed the mathematical description of spectral dependence for scattering by a spherical nanoparticle.
The theory accounts for the interaction of electromagnetic waves with a homogeneous medium differing in refractive index from the surrounding medium.
It is the foundation for determining particle sizes by scattering electromagnetic radiation.

Mie Theory (Further Detail)

Mie theory describes scattering and absorption of electromagnetic radiation by a sphere to understand colors of colloidal gold.
The approach expands the internal and scattered fields into vector harmonics to solve the wave equation, matching boundary conditions at the particle interface.

Size and Shape Dependence of Surface Plasmon Absorption

Size and shape significantly influence surface plasmon absorption. Graphs illustrate spectral locations, strengths (of the absorption), and numbers of plasmon resonances.

Semiconductor Nanoparticles

This section focuses on the theoretical calculations of energy levels in semiconductor conduction and valence bands.

Confinement Length (Semiconductors)

The equation for the Bohr radius is given.

Type of Confinement (Semiconductors)

Strong: a < a_B; Intermediate: a ~ a_B; Weak: a > a_B

Effect of Nanometer Scale

Confinement length directly affects energy systems and structures, changing physical and chemical properties.

Density of States

The density of states is described in relation to the model of a free-electron gas, in 3D, 2D, and 1D systems.

Two-Dimensional Systems (Quantum Wells)

The quantum well equation describing electron states is presented.

One-Dimensional Systems (Quantum Wires)

Equations for the density of states for quantum wires are shown.

Zero-Dimensional Systems (Quantum Dots)

The expressions for energy levels (E_e,h) are featured.
Quantum dots equations are featured in the presented information.

Energy Levels of a Semiconductor Quantum Dot

The equation for the energy levels (E_e,h) of a semiconductor quantum dot in relation to its size is presented in the provided text.

Optical Properties of Quantum Dots

The optical properties are size-tunable in nanostructures.

Effect of Quantum Confinement

The energy gap increases due to the reduction in nanoparticle size

QD's (Quantum Dots)

Quantum yield. Photoluminescence is influenced by size.

Core-Shell Nanoparticles

Different shaped core-shell nanoparticles are shown: spherical, hexagonal, multiple small core materials, nano matryushka, and movable core within hollow shell.
Properties are size and shape-dependent, influencing catalytic activity, selectivity, electrical/optical properties, SERS sensitivity, and plasmon resonance and melting point.
Descriptions of various types of core-shell nanoparticles (inorganic/inorganic, lanthanide-core) exist.
Types of core-shell nanoparticles (I and II) exist, with differing potential properties and photoluminescence behavior.

CdTe/CdSe core shell

Synthesis methods for CdTe/CdSe core shell are described.

Inorganic/Inorganic Lanthanide Core/Shell Nanoparticles

These nanoparticles exhibit upconversion and are promising for bio-sensing.
Equations for energy level calculations are included.

Upconversion Architecture

The advantages of back-reflectors in increasing device efficiency by at least a factor of two were mentioned.

Quiz

Questions related to schematics of synthesis and properties of various types of nanomaterials (e.g., core/shell, metal-based, polymer-based) are described.

Thermal Properties of Nanomaterials

A section on the influence of size and shape on the thermal properties of nanomaterials exists, including thermal conductivity. The influence of grain size/boundaries on thermal conduction is highlighted.

Physical Properties Change: Melting Point of a Substance

The definition of the melting point as the temperature when atoms/ions/molecules overcome intermolecular forces is shown.
Surface atoms require less energy due to contact with fewer atoms, impacting melting phenomena.

Melting Points

Lower melting points for nanostructures smaller than 100nm are noted.
Surface energy increase with decreasing size.

Melting Point Property

Melting-point depression is the decrease in melting point as material size decreases.

Physical Properties Example: Melting Point

The discussion contrasts the atomic arrangements at macroscopic and nanoscale levels to show their impact on the melting point effect.

Mechanical Properties of Nanomaterials

Stress and strain are fundamental descriptors to understand how materials respond under mechanical loading.
Concepts of strength, elasticity, plasticity, strain, stress, and material loading are discussed in relation to nanomaterials.

Strength

Strength is the ability of a material to withstand destruction from external loads.
Ultimate strength refers to the maximum stress a material can withstand before it breaks.

Elasticity

Elasticity describes the tendency of a material to return to its original shape after deformation when the cause of the deformation (stress or load) is removed.

Plasticity

Plasticity is the ability of a material to undergo permanent deformation without fracture.
Plastic deformation is only possible above the elastic limit..

Ductility

Ductility is the ability of a material to deform plastically (stretch) before fracturing.
Properties like percent elongation and reduction in area are used to measure ductility.

Hardness

Hardness measures a material's resistance to scratching, abrasion, cutting, indentation, or penetration.

Nanomaterials

Nanocrystalline materials exhibit properties related to grain size (nanoscale), impacting mechanical properties like hardness, yield strength, elastic modulus, and toughness. The properties of nanomaterials are dependent on their size and shape.

Nanocomposite

Nanocomposites are materials composed of two or more components with at least one component at the nanometer scale (1-100 nm). They contain inorganic/organic, inorganic/inorganic, and organic/organic phases.

Features of Nanocomposites

Physical sensitivity: Size effect and quantum confinement have major impacts.
Chemical reactivity: Increased gas absorption and non-stoichiometric compound formation are relevant.
Regrowth: Materials recrystallize more easily.
Rotation and Orientation: Crystallographic modifications from processing are notable.
Assembly: Easy aggregation in liquid/gaseous media results from their nanoscale size.

Classification of Nanocomposites

Ceramic matrix nanocomposites (CMC) have unique properties like high thermal resistance, chemical inertness, wear resistance, and corrosion resistance.
Metals and polymers also form nanocomposites with distinctive properties.

Processing Methods for Ceramic Nanocomposites

The descriptions of common methods of processing nanocomposites, including powder processing, polymer precursor processing, and sol-gel processing, are present in the provided information.

Applications of CMC's

Applications such as cutting tools, aerospace, jet engines, turbine blades, and hot fluid channels are cited.

Processing Methods for Metal-Based Nanocomposites

Several methods exist for producing metal-based nanocomposites, which often involve the melting of the related components and the manipulation of their consolidation or bonding procedures. These approaches are described in the provided text information.

Advantages and Limitations of Processing Methods of Metal Based Nanocomposites

The advantages and limitations of spray pyrolysis, liquid infiltration, rapid solidification processing, high energy ball milling, and chemical vapor deposition are separately presented in the data.

Processing Methods for Polymer-Based Nanocomposites

Intercalation Methods from Solution, In-situ Polymerization, Melt Intercalation, Template Synthesis, and Chemical Processes (Sol-Gel/Colloidal) are part of this section.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz explores key concepts related to plasmonic lasers and spasers, focusing on the roles of various materials and processes in their functioning. It covers topics such as the use of silica, organic dye molecules, and the mechanisms of coherent emission in these advanced optical devices.