additionally determined by particle size distribution and differences in morphology within the ensemble.
Quantum mechanical tunneling: A phenomenon in which the
wavefunction of a particle extends through a finite energy barrier,
such that the particle has a finite probability of being found in
regions where it could not be found under classical mechanics.
Tunneling allows particles to pass between quantum confined
regions.
Quantum mechanics: A system of physical laws developed since the
early twentieth century in which observable physical properties of
a system such as energy and momentum are limited to discrete
values. Quantum mechanics is necessary for describing many
nanoscale systems due to their small size limiting the number of
available quantum states.
Quantum number: A value that defines which eigenstate a quantum
mechanical system is in. Quantum mechanical systems may have
one or more quantum mechanical numbers depending on their
boundary conditions.
Raman scattering: A scattering process in which the light increases or
decreases in energy, often due to a change in vibrational energy of
the scattering molecule. Raman scattering is measured using
Raman spectroscopy, a vibrational spectroscopy technique.
Rate law: A mathematical relationship between the concentrations of
species in a reaction and the rate of the reaction. The constant of
proportionality is called the rate constant.
Rayleigh scattering: A process in which photons interact with a molecule or material without being absorbed or transferring any
energy and then continue in a random direction. The degree of
scattering is related to the wavelength of light being scattered and
the electric polarizability of the particles doing the scattering.
Reduced mass: A mathematical method for representing the mass of a
multibody system (e.g., two atoms in a diatomic molecule) as a
single mass.
Refractive index: The ratio of the speed of light in vacuum versus the
speed of light in vacuum, related to the dielectric constant at high
frequencies (e.g., visible light). If generalized as a complex number
Glossary
453
Quantum mechanical tunneling: A phenomenon in which the
wavefunction of a particle extends through a finite energy barrier,
such that the particle has a finite probability of being found in
regions where it could not be found under classical mechanics.
Tunneling allows particles to pass between quantum confined
regions.
Quantum mechanics: A system of physical laws developed since the
early twentieth century in which observable physical properties of
a system such as energy and momentum are limited to discrete
values. Quantum mechanics is necessary for describing many
nanoscale systems due to their small size limiting the number of
available quantum states.
Quantum number: A value that defines which eigenstate a quantum
mechanical system is in. Quantum mechanical systems may have
one or more quantum mechanical numbers depending on their
boundary conditions.
Raman scattering: A scattering process in which the light increases or
decreases in energy, often due to a change in vibrational energy of
the scattering molecule. Raman scattering is measured using
Raman spectroscopy, a vibrational spectroscopy technique.
Rate law: A mathematical relationship between the concentrations of
species in a reaction and the rate of the reaction. The constant of
proportionality is called the rate constant.
Rayleigh scattering: A process in which photons interact with a molecule or material without being absorbed or transferring any
energy and then continue in a random direction. The degree of
scattering is related to the wavelength of light being scattered and
the electric polarizability of the particles doing the scattering.
Reduced mass: A mathematical method for representing the mass of a
multibody system (e.g., two atoms in a diatomic molecule) as a
single mass.
Refractive index: The ratio of the speed of light in vacuum versus the
speed of light in vacuum, related to the dielectric constant at high
frequencies (e.g., visible light). If generalized as a complex number
Glossary
453