What is Excited: Definition and 171 Discussions

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). 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 raised to an excited state. The temperature of a group of particles is indicative of the level of excitation (with the notable exception of systems that exhibit negative temperature).
The lifetime 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 return to a lower energy level is often loosely described as decay and is the inverse of excitation.
Long-lived excited states are often called metastable. Long-lived nuclear isomers and singlet oxygen are two examples of this.

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  1. H

    I Confused about slater determinant for excited states

    Hi all, I have a question about Slater Determinant for excited states. Let's say we want to construct approximate (2 level) wavefunction of He in some certain state. Since we have two electrons in two level system with spin in consideration, we can construct total of 4 different wavefunctions...
  2. samjohnny

    Electron Configuration of Excited State

    Homework Statement An exercise examining the tin atom (Sn). Tin has a ground state electron configuration of ##[Kr]4d^{10}5s^25p^2##. a) Write down the electronic configuration of the first excited state. b) Illustrate with a vector diagram the allowed total angular momentum ##J## values for...
  3. R

    Relating excited state molecular emission to chemical reaction

    .. reaction. This may seem a nonsensicle question but I'll go ahead anyway. Say if I have a process that has an emission spectra dominated by excited state molecular emission, can I relate this in any way to the amount / number of chemical reactions occurring? Thanks for any help
  4. D

    Excited States of The Deuteron

    All textbooks and material that I've read on the topic state that the deuteron being a weakly bound system, has no excited state. They also go on to state that the deuteron exists as a mixture of ##^3 S_1## and ##^3D_1## states. So, are these states degenerate in energy? That is, are both of...
  5. Coffee_

    BEC question about number of excited particles

    Assuming no interactions, and the energy levels ##\epsilon_j## for a single particle state, the occupation number for this state for a system of particles is given by: à ##n_j=\frac{1}{exp(\frac{\epsilon_j-µ}{kT}) - 1}## (1) (Here comes argument 1) We conclude that the maximal value that µ...
  6. Q

    Base excited stacked mass spring damper systems

    Homework Statement I'm trying to derive the equations of motion and state space as well as the transfer function for a system which has two mass spring damper systems stacked on top of each other. The system is base excited. I attached a pic of the system Homework Equations - Sum of the...
  7. Samurai44

    Zero Potential Level: Excited State or Not?

    Greetings , Is the zero potential level ( not the ground state) considered as an excited state ? and why the ground state isn't an excited state ?
  8. VoteSaxon

    Fraction of thermally excited atoms

    Homework Statement There is an electronic transition between the first energy state and the ground state of a neon atom, emitting a wavelength of 746nm. The question asks for the energy of the transition and an estimate of the fraction of atoms in a sample that is thermally excited at 300K...
  9. J

    Is the Net Charge of a Hydrogen Atom the Same in Excited State vs Ground State?

    if in a hydrogen atom the electron is in a excited state, is the net charge the same vs ground state? what is the difference between charge and energy here? thx
  10. S

    Faraday generator self excited

    Good day, some time ago i asked a similar question but i didnt get a definitive answer. I will try to write as simple as possible, A faraday disc (generator) a constant rpm torque source that spins the generator , now i put some load on the brushes attached to the disc and a capacitor in...
  11. G

    Excited state line width and thermodynamics

    I would appreciate very much if you could help me with a puzzling question that seems a paradox to me. Every excited state of an atom (every line of the characteristic spectrum) has a “width”: the higher the width, the shorter the lifetime of the state, and when the atom de-excitates we get...
  12. ShayanJ

    Spin-3/2 particle and degeneracy in excited state

    Homework Statement Consider a particle with mass m in the following 1D potential: V(x)=\left\{ \begin{array}{lr} mgx \ \ \ x>0 \\ \infty \ \ \ \ \ \ \ x\leq 0 \end{array} \right. What is its minimum energy calculated using the uncertainty relation? Homework Equations \Delta x \Delta p...
  13. U

    Two particle collision - One in excited state

    Homework Statement (a)Find energy of photon emitted (b)Show that relative velocities after de-excitation are reversed (c)Find an expression for CM frame energy and find momentum of either particle in CM frame (d)Consider now, for a nuclear process and describe the initial and final conditions...
  14. Z

    Could Excited Baryon decay into omega meson and baryon?

    Excited baryon could decay into photon and ground state baryon,but could it decay into omega meson and ground state baryon?Could you introduce me some articles about it,experimental or theoretical?
  15. gracy

    Understanding Benzene: Visible Light and Excited Electrons

    know benzene is colourless...but i can't seem to get my head around it at the moment! As benzene has delocalised electrons, it should require less energy to excite the electrons. And Visible light is a lower frequency to UV? So according to the equation: E=hv Benzene should be coloured as it...
  16. B

    Fraction of electrons excited above fermi level

    For the fermi dirac distribution function for temperatures higher than 0 K, how do we approximate the number of electrons available for conduction?
  17. M

    Forming an Excimer - Explaining the Process for Xenon

    Hello, first post! Can anyone explain to me how an excimer is formed? Considering Xenon. I've gathered that an excited state Xe*, ground state Xe, and a 3rd body M react resulting in an Xe* excimer + M(carrying away excess energy). I'm struggling to find how the ground state Xe can have any...
  18. Z

    Carriers in Ag. Are these excited conduction electrons?

    Homework Statement I am attempting to solve a question which asks the carriers in Ag. Homework EquationsThe Attempt at a Solution Is the use of the word 'Carriers' simply another way of saying excited conduction electrons? Thank you.
  19. P

    Finite square well, excited states

    Homework Statement Consider a particle of mass m in the ground state of a potential well of width 2 a and depth. the particle was in the ground state of the potential well with V0 < Vcritical, which means the well is a narrow one. At t = 0 the bottom of the potential well is shifted down to Vo'...
  20. T

    Wave Function from ground to excited

    I now understand how the wavefunction graphs look from the hyperphysics: http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/hosc5.html. However, what I fail to understand, is how the wavefunction equation was derived for the 1st excited state, from: ground_wavelength0 = (a/pi)1/4 e(-ax2/2)...
  21. H

    How electrons are excited in direct transitions?

    When a photon is radiated to a direct gap semiconductor and an electron is excited from valence band minimum to conduction band maximum, the applied force on the electron is zero (because k isn't changed) but the electron acquires energy. What is the source of the energy obtained by the electron...
  22. C

    Atomic Model of Hadrons mass of excited particles

    So in a lecture I'm reading up on we are given questions to answer during the lectures with no answers, and for this particular lecture the answer has been omitted and it is in none of our textbooks. But basically it says that a proton and a sigma plus, both have the same quark composition...
  23. G

    Transition between excited states

    Homework Statement An atom in an excited state has a lifetime of 1.2 x 10 -8 sec; in a second excited state the lifetime is 2.3 x 10 -8 sec. What is the uncertainty in energy for the photon emitted when an electron makes a transition between these two levels? Homework Equations...
  24. K

    Do protons have excited states?

    Do protons and neutrons have excited states? This page shows some simulated shapes of protons. http://discovermagazine.com/2003/aug/breakprotons Do the different shapes have to do with different energy states of the proton?
  25. K

    What is the relationship between wavelength and excited shells in atoms?

    is the wavelength equal to the distance between the excited state shell and the rest state shell?
  26. T

    Can AC Excitation Remove Offset Error in a Wheatstone Bridge Torque Meter?

    I have a torque meter using a full-bridge Wheatstone bridge (all legs are strain gauges). The bridge has some non-zero, unknown offset (it's old). I would like to strip this offset out prior to signal amplification. My theory is, under DC conditions, the offset exists, which mucks up the...
  27. R

    Find the spectrum of the 2nd excited states.

    Homework Statement A state at the 2nd exited level is of the form: ##|\epsilon>=(\epsilon_{\mu\nu}\alpha^\mu_{-1}\alpha^\nu_{-1}+\epsilon_{\mu}\alpha^\nu_{-2})|0;p>## Find the spectrum of the 2nd excited states, the value of the mass squared, the condition for the state to be physical, and the...
  28. R

    Photon emission by an excited hydrogen atom

    Typically (in popular literature) the process of photon emission by an excited atom is considered as an instant event. But actually it is quite likely that it is a continuous process. Such processes are usually described by evolutionary differential equations (ODEs or PDEs). Assume that we...
  29. B

    Difference between J/Psi and its excited states

    The J/Psi is a state of charmonium with J=1, S=1, L=0. So J^{PC} = 1^{--}. It can be excited to states J^\prime \textrm{ and } J^{\prime\prime}, but these don't change any of these numbers. So what is changing?
  30. A

    Principal Quantum Number of the Excited Oxygen atom.

    Normally, Oxygen has 8 electrons in its neutral form that is 1s2 2s2 2p4. In this case, its principal quantum number (n) is two. But what happens if it got excited and its electronic configuration becomes 1s2 2s2 2p3 3s1? In this case, Is the principal quantum number (n) of oxygen two or...
  31. K

    Probability of a particle in a box in the first excited state.

    Homework Statement A particle is in the first excited state of a box of length L. Find the probability of finding the particle in the interval ∆x = 0.007L at x = 0.55L. Homework Equations P = ∫ ψ*ψdx from .543L to .557L The Attempt at a Solution Normalizing ψ gives ψ=√(2/L)sin(nπx/L)...
  32. W

    Equilibrium bond lengths for excited molecules

    When making the Morse Potential graphs of diatomic molecules going through a transition, the excited state sometimes has a different equilibrium bond length. A visual example is here: http://en.wikipedia.org/wiki/File:Franck-Condon-diagram.png I was wondering how the average bond length of...
  33. J

    Phase of photon from excited atom

    Imagine that an excited hydrogen atom in the symmetric 2s state emits a photon. We use a birefringent crystal to split the photon into vertical and horizontal components. Is the phase relation between these components random or is it the same for every photon emitted by a similarly excited...
  34. F

    Angular momentum of excited electron in hydrogen

    I am sure there must be a better way to do this, but I just used the method I thought would work. Essentially, I just want to find n and put that in p=nh2π, but my method to find n will give me a complex answer, which is clearly not what I am looking for. If someone could either tell me what...
  35. R

    Calculate the energy spread of the Fe-57 first excited state

    Homework Statement Calculate the energy spread of the 57Fe first excited state, which has energy 14.4 keV and lifetime 141 ns. Homework Equations \Gamma\tau=\hbarThe Attempt at a Solution No idea what this is really asking me. is it really just \Gamma=\frac{\hbar}{\tau} assuming it's not...
  36. V

    I'm confused about this excited electron configuration

    I have already turned in my homework for chemistry however I'm still confused about this question: Which electron configuration is in an excited state? a.1s2 2s2 2px2 b.1s2 2s1 2px1 2py1 2pz1 My teacher told me that the only choice b was excited because choice a was in violation of Hund's...
  37. G

    Excited states and selection rules

    If you have a meson in the states ## ^3S_1## and ## ^1S_0 ## this means that ##J^P = 1^+ ## and ## 0^+## doesn't it? But if you have excited states ## ^1P_1 ## this is ##J^P=1^- ## but isn't ## ^3P_1 ## supposed to be ##J^P = 1^- ##? Does this matter? ##^3P_0##, ##^3P_1## and ##^3P_2## for...
  38. NanaToru

    Pacific Rim has monsters and giant robots who else is excited?

    I'm really looking forward to it, especially with Rinko Kikuchi and Idris Elba in the movie. but giant monsters fighting giant robots (Or mech suits, if we are getting technical) sounds awesome.
  39. E

    Energy uncertainty of an atom in an excited state

    Homework Statement A Na atom is in an excited state for a mean time of 1.6 \times 10^{-8}s. Then it jumps to the ground state emitting a photon with 2.105 eV of energy. Find the energy uncertainty of that excited state. Homework Equations The Attempt at a Solution I don't even...
  40. C

    Obtaining Higher Angular Frequencies in QHO Excited States

    Maybe the answer to this should be obvious, but if the quantum harmonic oscillator has a natural angular frequency \omega_0, why do the excited states vibrate with higher and higher angular frequencies? How do we obtain these frequencies? Thanks!
  41. M

    Find the Initial and Final states of an excited Hydrogen Atom

    Homework Statement A hydrogen atom in an excited state absorbs a photon of wavelength 434 nm. What were the initial and final states of the hydrogen atom? Homework Equations 1/λ=1/91.127 * (1/nf2-1/ni2) The Attempt at a Solution Tried to use the equation, but keeping the initial...
  42. F

    Signal excited by square wave

    Homework Statement 11. What kind of frequency components can be observed in the output if a linear system is excited by a symmetric square wave? 12. What kind of frequency components can be observed in the output if a non-linear system is excited by a symmetric square wave? Homework...
  43. E

    Determining the life time of a excited state.

    Homework Statement The smallest uncertainty in the frequency of emitted light when excited atoms return to ground state for molecules is estimated to be 8 MHz. Use this information to estimate the lifetime of the excited states. I would like to know if I'm thinking correct. Homework...
  44. V

    What happens after an electron is excited by a photon?

    I understand the concept of an electron being raised from it's ground state by a photon with the correct wavelength, but then what? I ask because if the electron remained in it's excited state then surely shining a bright light on a material for long enough would 'saturate' it's electrons and...
  45. Spinnor

    A jump rope in the ground state gets excited.

    Say two girls spin a jump rope, of length ∏ meters, so that the only nodes are where the girls hold the rope, ψ= sin(x)exp(iω_1t) (actually there are no nodes at the girls hands as where they hold the rope goes in a smallish circle). Now instruct the girls how to shake the rope so as to most...
  46. atomqwerty

    Hydrogen excited with polarized light?

    Hello, First of all, i know I should use the template for this, and I apologize for that, but the thing is I don't even know how to begin to solve the next problem, and it's very important for me and for my tomorrow's afternoon exam. It's quite qualitative, and I'm sure most of you will know...
  47. P

    Spring-mass system in an excited box

    Homework Statement Well, I have this spring (stiffness k and free length l_{0}) mass ( m ) system in a box which has a width w such that l_{0}>w (i.e. the spring is compressed). The box is excited (given a prescribed position) by: u(t)=b\cdot sin({\omega}\cdot t). Determine the range of...
  48. D

    Bohr model question - transition between first excited state and ground state

    Homework Statement In a hydrogenlike ion with atomic number Z, the energies of the allowed states are given by E(n) = (-13.6eV) (Z^2/n^2) What is the wavelength asociated with the transition between first excited state and ground state of hydrogen-like helium? (He+) Homework...
  49. S

    Estimate the lifetime of the excited state that produced this line.

    Homework Statement An atomic spectrum contains a line with a wavelength centered at 460 nm. Careful measurements show the line is really spread out between 459 and 461 nm. Estimate the lifetime of the excited state that produced this line. Homework Equations Change in Frequency =...
  50. F

    Calculating Wavelength and Energy of Excited Hydrogen Atom | Help Guide

    help please, for question: a hydrogen atom, initially in ground state, absorbs a photon, and is excited to its second excited state. What were the wavelength and the energy of the photon by the atom. Did i do it right. 1/λ = (1.097*10^7)(1/n1^2 - 1/n2^2) 1/λ = (1.097*10^7)(1/1^2 -...
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