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.
when an electron is excited to the conduction band is it move further from the nucleus?
Are free electrons in the conduction band further from valence electrons?
I saw this picture that seems problematic to me. what do you think?
Hello, so for this question I know how to solve it but I still have a few questions. First when the question means it's rated at 20 HP and 600 V, it's referring to the source voltage and Pin correct? Also in order to solve this question, the rotation loss Prot was neglected. This was because at...
I'm solving problem number 5 from https://ocw.mit.edu/courses/8-05-quantum-physics-ii-fall-2013/resources/mit8_05f13_ps2/.
(a) Here I got:
$$
\beta = \frac{\hbar^{\frac{1}{3}}}{(\alpha m)^\frac{1}{6}}
$$
and:
$$
E = \left ( \frac{\alpha \hbar^4}{m^2} \right )^\frac{1}{3}e
$$
(b) Using Scilab I...
Hi,
I am have trouble finding whether or not the topic is possible.
It concerns an electronic dipole.
I am well familiar with the general rules: https://en.wikipedia.org/wiki/Selection_rule
Is it possible for transitions to occur from e.g. ^4P_1/2 and ^4P_2/3, which are both in n=3?
If they...
Hello, I work with a spectrometer that does ionizations through laser 2+1 photons resonant ionization (a high power narrow bandwidth laser is tuned to a precise wavelenght so that it allows reaching an excited energy level of a particular element with the sum of two photons absorbed...
I'm trying to figure out why emission nebulae glow.
I read various sites such as a NASA website explaining why they shine;
'The massive stars embedded within the nebula give off enormous amounts of ultraviolet radiation, ionizing the gas and causing it to shine.'
The Britanica article on...
For part b)
Gamma is the cavity loss coefficient, L is the length of the rod, R1,2 are the reflectivities. I am not sure how to find the number of ions in the excited state since I don't know the number of ions in the ground state.
Five electrons are in a two-dimensional square potential energy well with sides of length L. The potential energy is infinite at the sides and zero inside. The single-particle energies are given by (h^2/8mL^2) (nx^2+ ny^2) where nx and ny are integers. The energy of the first excited state of...
Hello! Assume we have a simple harmonic oscillator potential, in 3D (say created by some electric fields, such as a Paul trap) and inside it we have a 2 level system in the excited state (say an ion in which we care only about 2 levels, for example the lowest 2). The translational energy of the...
Hi I'm doing a uni project and need help with a Self Excited AC Single Phase Generator. I'm using an AC Single Phase Induction Motor to act as the generator. Its turned by a DC Motor
The AC motor is 1350 RPM and the DC motor is 2500 RPM
Its not producing any electricity (just a few volts) for...
I know how to solve this problem when the energy at ground state is zero but I don't know how to deal with 1st excited state energy as zero.
According to me since the potential energy is zero therefore the kinetic energy must be 13.6eV according to conservation of energy.
I also know that the...
Here is a question I have been given
I have started by setting up the formula and rearranging for n_2
Only problem is that I do not know the quantum number for ground state? What value do I sub in for n_1?
Any help would be appreciated! Thanks
Hello! I am reading about excited levels in nuclei (I am mainly following Wong's nuclear physics book) and I am a bit confused about the nature of the excited states. In the one particle picture (mainly shell model) the excitation appears as static i.e. one nucleon moves from a certain orbital...
Hello! How are the parity and spin of excited states of nuclei measured experimentally. I imagine that the energy can be easily measured by exciting the nucleus (by colliding it with a nucleon or electron for example) and then measuring the emitted photons. But how can one infer the spin and...
Hi there, popping by here to check my answer because another online platform has already answered it but my answer appears to be wrong. I can't seem to understand why though :/
Since I can find the energy at a state to be ##E_{n}=\dfrac {-13.6z^{2}}{n^{2}}eV##
At ground state where n=1...
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I have a momentum-shifting operator ##e^{i\Delta p x/\hbar}## acting on the ground state ##\ket{0}## of the QHO, and I want to compute the overlap of this state with the n##^{th}## excited QHO state ##\ket{n}##. Given...
When electrons get excited they are unstable, therefore they want to go back to ground state. One way they do so is by creating photons (e.g. mirrors), but I've also read that they can create electricity (another electron?). Photoelectric is how it's called, right? If so, how can we choose...
Mainly I want to know the following thing: electrons when excited they tend to want to go back to ground state, right? One way is by photons, but how does that work? Accelerating charges creates EM waves, but in this case there was no acceleration, right? Or is the term accelerating only a way...
Tonight I'm taking my wife and parents to Brian Cox's World Tour "ADVENTURES IN SPACE & TIME" with sidekick Robin Ince. All his European stops sold out and so far all of his US stops have been close to selling out. I've been impressed because he's not quite the household name Neil deGrasse Tyson...
this is from a website on why gamma rays are released what i don't understand is, why is the mass defect lead to a gamma radiation to be formed. If the nucleus is excited and dexcites the change in energy levels would cause a photon to be released. yet here it says the mass defect is the source...
I am learning for my exam in particle physics. One topic is statistical physics. There I ran into this question:
Consider an atom at the surface of the Sun, where the temperature is 6000 K. The
atom can exist in only 2 states. The ground state is an s state and the excited state at
1.25 eV is a...
Most of the books I've seen they say that the first excited state of Helium (with two electrons, one in orbital 1s and other in 2s) can have the two electrons with parallel spin (orthohelium) or anti-parallel spin (parahelium).
If ##\operatorname{X_{↑}}{\left (n \right )}## represent the state...
Homework Statement
So in my problem, there's a given of 3 non interacting fermions in a harmonic well potential. I already got the wavefunction but i have problems in obtaining the ground state energy and its 1st excited state energy for 3 fermions (assuming they are non interacting and...
Hey guys, I am looking for a database on gamma emission from the first few excited states of known isotopes for a piece of software we are putting together. Any format is fine.
Thanks!
The figure below is from a textbook. It is explaining what excited states are using carbon as an example. I don't necessarily agree that the the state labeled as "example excited state 1" is really an excited state. Since the electrons in the 2p orbitals are unpaired, and in the absence of a...
Holographic Relations for OPE Blocks in Excited States
https://arxiv.org/pdf/1809.09107.pdf
Jesse C. Cresswell†1 , Ian T. Jardine†2 , and Amanda W. Peet†§3 †Department of Physics, University of Toronto, Toronto, ON M5S 1A7, Canada §Department of Mathematics, University of Toronto, Toronto, ON...
i would like to find the detailed calculation in the case of a two slits experiment with an excited atom.
i only found the formulas when it decays near the slits.
have you links?
thanks
The Atom of Helium is doubly excited in 2p2 1D
Can someone explain to me how these energy symbols work? I have a problem with what the 1D means specifically. I know 2p2 means two electrons in the 2p state. The 1 in 1D could be referring to electron being in a singleton, but I don't understand...
Homework Statement
The total spin of an Mg atom is zero and remains zero after absorption or emission of a photon. To which states can one of the electrons in the outer shell get by absorption of a single photon: 4s, 5s, 3p, 4p, 3d, 4d?2. The attempt at a solution
I am not sure which of the...
Homework Statement
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Estimate the lifetime of the excited state of an atom whose natural emission line width is 3.00 × 10−4 eV.
Homework Equations
$$ \Delta E \Delta t = \frac{1}{2} \times \frac{h}{2\pi} $$
$$ \Delta E \Delta t = \frac{h}{2\pi} $$The Attempt at a Solution
I think all I...
Homework Statement
Considering the molecule of ##C_2^+## in an excited state with valence configuration ##2\sigma_g^2## ##2\sigma_u^2## ##1\pi_u^2## ##3\sigma_g^1##. Finding all the possible term symbol.
Homework Equations
Term symbol ##^{2S+1}\Lambda##
##L=0 \rightarrow \Sigma##
##L=1...
Mesons and baryons have both a ground state and excited states involving the same valence quarks but a higher mass (which can in principle be calculated from QCD).
Fundamental fermions and bosons, however, do not appear to display this behavior. They have a ground state, and while there are...
Hi,
It has been a long time since I studied synchronous machines and I am trying to understand the mechanism of how the armature excitation can result in the generator being lagging or leading. So please correct me if I say something like it's axiomatic but its really erroneous.
Now, according...
I learned that the probability of radioactive decay for an atom is always the same. However, is the decay of and excited atom or electron non linear(decay probability varies with time)?
My question is the following one:
If i have the first excited state of helium, the possibilities for the two electrons are : 1s+,2s+ , 1s+2s-, 1s-,2s- and 1s-,2s+ , where + and - denotes spin up and down. If I use the slater's determinant to generate antisymmetric states, I get :
$$|u1> =...
I think I got this right, I just want a second opinion to know if my concepts are correct
1. Homework Statement
20Na decays to an excited state of 20Ne through the emission of positrons of maximum kinetic energy 5.55 MeV. The excited state decays by ##\alpha## emission to the ground state of...
I am currently studying a Foundation Program, which includes chemistry.
-I can easily understand the distinguishable characteristics between ground and excited state via writing the electron configuration.
-But how can an tom changes from ground to excited state ? And can an atom changes from...
Homework Statement
A 180V separately excited DC motor has an armature resistance of 1.2ohm. When the note runs at 1200rpm,t he armature current is 10A.
1) Assuming that motor torque is constant at all speeds,d determine the mechanical torque and power developed in the motor.
2)Find the speed of...
Homework Statement
Transitions between n=109 to n=108 have been observed in highly excited helium atoms and in this case the Bohr model is a valid approximation. Why is this?
Homework Equations
N/A
The Attempt at a Solution
I'm having some problems with this question and it probably comes...
Homework Statement
The spin-orbit interaction in sodium results in fine structure with energy shifts given by:
##\Delta E_j = \frac{C}{2}[j(j+1)-l(l+1)-s(s+1)]##
If ##l##, ##s## and ##j## describe the single outer electron in sodium. Show that if this electron is excited to a state where l>0...
I am looking at a paper that takes about thermally excited holes in relation to photocatalytic destruction, another paper with the same substance (TiO2) talks about decomposition of polycarbonates with the same method (thermally excited holes). I'm a little rusty on this topic. Please could...
Homework Statement Consider the following example from a previous exam. We are to predict the spin and parity for F(A=17,Z=9), Florine, in the ground state and the first two excited states using the shell model.
Ground state:
Neutrons: (1s 1/2)^2 (1p 3/2)^4 (1p 1/2)^2
Protons: (1s 1/2)^2...
Hi all!
I have the following spectrum for a signal force:
and this is a zoom in the range of interest:
Can I state that this force is capable of exciting the natural frequency of the structure ( in the range 5-30Hz) or the force amplitude in this range is too low compared to the peak...
Homework Statement
A glass prism is used to launch an evanescent wave along a glass-air interface. What is the minimum incident angle to excite the evanescent wave?
Homework EquationsThe Attempt at a Solution
I don't understand what the question is asking for. I have read and reread the...
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...
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...