FACTOID # 18: Alaska spends more money per capita on elementary and secondary education than any other state.
 
 Home   Encyclopedia   Statistics   States A-Z   Flags   Maps   FAQ   About 
   
 
WHAT'S NEW
 

SEARCH ALL

FACTS & STATISTICS    Advanced view

Search encyclopedia, statistics and forums:

 

 

(* = Graphable)

 

 


Encyclopedia > Excited state
After absorbing energy, an electron may jump from the ground state to a higher energy excited state.

Excitation is an elevation in energy level above an arbitrary baseline energy state. In physics there is a specific technical definition for energy level which is often associated with an atom being excited to an excited state. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... A quantum mechanical system can only be in certain states, so that only certain energy levels are possible. ...


In quantum mechanics an excited state of a system (such as an atom, molecule or nucleus) is any quantum state of the system that has a higher energy than the ground state (that is, more energy than the absolute minimum). The temperature of a group of particles is indicative of the level of excitation. Fig. ... Properties In chemistry and physics, an atom (Greek ἄτομος or átomos meaning indivisible) is the smallest particle still characterizing a chemical element. ... In science, a molecule is a group of atoms in a definite arrangement held together by chemical bonds. ... The nucleus of an atom is the very small dense region, of positive charge, in its centre consisting of nucleons (protons and neutrons). ... A quantum state is any possible state in which a quantum mechanical system can be. ... In physics, the ground state of a quantum mechanical system is its lowest-energy state. ... This article includes a list of works cited or a list of external links, but its sources remain unclear because it lacks in-text citations. ...


The lifetime (see resonance) of a system in an excited state is usually short: spontaneous or induced emission of a quantum of energy (such as a photon or a phonon) usually occurs shortly after the system is promoted to the excited state, returning the system to a state with lower energy (a less excited state or the ground state). This article is about resonance in physics. ... Spontaneous emission is the process by which a molecule in an excited state drops to the ground state, resulting in the creation of a photon. ... In optics, stimulated emission is the process by which, when perturbed by a photon, matter may lose energy resulting in the creation of another photon. ... In modern physics the photon is the elementary particle responsible for electromagnetic phenomena. ... Normal modes of vibration progression through a crystal. ...

Contents

Atomic excitation

A simple example of this concept comes by considering the hydrogen atom. Depiction of a hydrogen atom showing the diameter as about twice the Bohr model radius. ...


The ground state of the hydrogen atom corresponds to having the atom's single electron in the lowest possible orbits (that is, the spherically symmetric "1s" wavefunction, which has the lowest possible quantum numbers). By giving the atom additional energy (for example, by the absorption of a photon of an appropriate energy), the electron is able to move into an excited state (one with one or more quantum numbers greater than the minimum possible). If the photon has too much energy, the electron will cease to be bound to the atom, and the atom will become ionised. e- redirects here. ... In chemistry, an atomic orbital is the region in which an electron may be found around a single atom. ... This article discusses the concept of a wavefunction as it relates to quantum mechanics. ... Quantum numbers describe values of conserved quantity in the dynamics of the quantum system. ... In modern physics the photon is the elementary particle responsible for electromagnetic phenomena. ... In physics, a bound state is a composite of two or more building blocks (particles or bodies) that behaves as a single object. ... An electrostatic potential map of the nitrate ion (NO3−). Areas coloured red are lower in energy than areas colored yellow An ion is an atom or group of atoms which have lost or gained one or more electrons, making them negatively or positively charged. ...


Once the electron is in its excited state, we deem the hydrogen atom to be in its excited state. The atom may return to a lower excited state, or the ground state, by emitting a photon with a characteristic energy. Emission of photons from atoms in various excited states leads to an electromagnetic spectrum showing a series of characteristic emission lines (including, in the case of the hydrogen atom, the Lyman series, the Balmer series, the Paschen series, the Brackett series.) Legend γ = Gamma rays HX = Hard X-rays SX = Soft X-Rays EUV = Extreme ultraviolet NUV = Near ultraviolet Visible light NIR = Near infrared MIR = Moderate infrared FIR = Far infrared Radio waves EHF = Extremely high frequency (Microwaves) SHF = Super high frequency (Microwaves) UHF = Ultra high frequency VHF = Very high frequency HF = High... A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from an excess or deficiency of photons in a narrow frequency range, compared with the nearby frequencies. ... The Lyman series is the series of transitions and resulting emission lines of the hydrogen atom as an electron goes from n ≥ 2 to n = 1 (where n is the principal quantum number referring to the energy level of the electron). ... Two of the balmer lines (α and β) are clearly visible in this emission spectrum of a deuterium lamp. ... The Paschen series is the series of transitions and resulting emission lines of the hydrogen atom as an electron goes from n ≥ 4 to n = 3 (where n refers to the energy level of the electron). ... The Brackett series is a series of absorption or emission lines that are due to electron transitions between the fourth and higher energy levels of the hydrogen atom. ...


Perturbed gas excitation

A collection of molecules forming a gas can be considered in an excited state if one or more molecules are elevated to kinetic energy levels such that the resulting velocity distribution departs from the equilibrium Maxwell-Boltzmann distribution. This phenomenon has been studied in the case of a two-dimensional gas in some detail, analyzing the time taken to relax to equilibrium. It has been suggested that the section Physical applications of the Maxwell-Boltzmann distribution from the article Maxwell-Boltzmann distribution be merged into this article or section. ... A two-dimensional gas is a collection of N objects which are constrained to move in a planar or other two-dimensional space in a gaseous state. ...


See also

The Rydberg formula (Rydberg-Ritz formula) is used in atomic physics for determining the full spectrum of light emission from hydrogen, later extended to be useful with any element by use of the Rydberg-Ritz combination principle. ... A quantum state is any possible state in which a quantum mechanical system can be. ... In quantum mechanics, a stationary state is an eigenstate of a Hamiltonian, or in other words, a state of definite energy. ...

External links

  • Picture of a hydrogen atom changing from ground state to an excited state
  • NASA background information on ground and excited states
 This quantum mechanics-related article is a stub. You can help Wikipedia by expanding it.

  Results from FactBites:
 
Excited state - Wikipedia, the free encyclopedia (292 words)
In quantum mechanics, an excited state of a system (such as an atom, molecule or nucleus) is any quantum state of the system that has a higher energy than the ground state (that is, more energy than the absolute minimum).
The ground state of the hydrogen atom corresponds to having the atom's single electron in the lowest possible orbit (that is, the spherically symmetric "1s" wavefunction, which has the lowest possible quantum numbers).
The atom may return to a lower excited state, or the ground state, by emitting a photon with a characteristic energy.
NationMaster.com - Encyclopedia: Excited state (1012 words)
Spontaneous emission is the process by which a molecule in an excited state drops to the ground state, resulting in the creation of a photon.
State densities can be calculated by adding together the densities arising from various microstates, weighted by their contribution to the overall state.
The linear combinations of microstates in the state functions are given in the output, as shown in Figure 6.10.
  More results at FactBites »

 
 

COMMENTARY     


Share your thoughts, questions and commentary here
Your name
Your comments

Want to know more?
Search encyclopedia, statistics and forums:

 


Press Releases |  Feeds | Contact
The Wikipedia article included on this page is licensed under the GFDL.
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms, 1022, m