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Questions tagged [atomic-physics]

Atomic physics is the field of physics that studies atoms as an isolated system of electrons and an atomic nucleus. It is primarily concerned with the arrangement of electrons around the nucleus and the processes by which these arrangements change. This includes ions as well as neutral atoms and, ...

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Given the wavefunction of an electron in hydrogen, what possible energies can it obtain and what are the probabilities of those energies?

we are given, $$\psi(\textbf{r})=A\left[R_{2,1}(r)Y_{1,-1}(\theta,\phi)+iR_{2,1}(r)Y_{1,0}(\theta,\phi)+2R_{2,1}(r)Y_{1,1}(\theta,\phi)\right]$$ we can rewrite this as: $$\left|\psi(\textbf{r})\right&...
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How does mirror reflect light (according to quantum mechanics)? [duplicate]

We all know that light is reflected from mirror but my question is that what happens at Quantum level when the process of reflection is happening? does the photon first get absorbed and then re-...
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What causes the transition $J=0\to J^\prime=0$ absolutely forbidden?

For many-electron atoms, the dipole selection rules are $\Delta M_J=0,\pm 1$ and $\Delta J=0,\pm 1$ with the transition $J=0\to J^\prime=0$ absolutely forbidden. This remains true even for quadrupole ...
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Why there is no even order in high-order harmonics generation of noble gas?

As we all know, there is no even-order peaks in HHG of noble gas. I understand this phenomenon by the knowledge here: there will be odd and even peaks in the frequency domain when we do fourier ...
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Intuition behind Pauli’s Principle

While reading about electronic structure of multi-electron atoms, Pauli’s Principle comes out to be a very important feature. But it feels very vague as little explanation is given about it. I mean ...
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How does Brownian motion prove the existence of atoms?

I have heard many people say that the existence of atoms is proven by Brownian motion. Now, I understand how an atomic theory would suggest the existence of Brownian motion. However, who is to say ...
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27 views

Softwares/packages on light-matter interaction [closed]

I'm interested in computational physics (and a total newbie). Are there any softwares and/or packages (like quantum espresso, abinit, or lammps etc.) that can simulate what happens to the properties ...
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Switching off AC current supplied to RF coil on atoms instantly

Imagine if you have an ensemble of cold atoms aligned parallel to a large field along z direction. Then, I apply a magnetic field of the form $A\cos(\omega_{rf} t)$ transverse to the spin (created by ...
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Energy of not absorbed photon

If a photon was incident towards an atom colliding with its electron without being absorbed by it because it has less or more energy from the required, then what will happen to the Photon next? Will ...
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VASP: What level of theory is used to consider the spin-orbit coupling (SOC) term. Is it an averaged spin-orbit (S-O) treatment?

I am using the VASP code and I have a few questions on the implementation of spin-orbit coupling. What level of theory is used to consider the SOC term, and is it an averaged S-O treatment? The ...
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Does chemical bonding decrease the entropy of the universe?

I have read in many credible texts ( including "a brief history of time" ) that nature always increases entropy, that is, the entropy in the universe increases. But I learnt that atoms and molecules ...
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How can Coulomb's Law work in derivation of atomic radius? [duplicate]

Coulomb's Law for the force between two charges do not work for moving charges. For a single electronic atom, the electron moves around the nucleus. But in deriving the formula for finding an atom's ...
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Rutherford gold experiment

When an alpha particle is nearing the gold atoms nucleus, it is slowing down due to electrostatic repulsion, right? But then why is the acceleration or velocity not a minimum at that point (the ...
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1answer
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Dose attenuation decrease frequency

What cause the transveres decay in nmr? From wiki I have an understanding that it has somthing to do with decoherence which is caused by spin of one atom effecting anouther. That my basic understand,...
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3answers
112 views

What is the meaning of natural line broadening?

I have recently found one exercise in an exercise book: During the transition from the first excited state of a hydrogen atom into the ground state, photons with a wavelength of 121.5 nm are ...
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0answers
33 views

Faraday, Avogadro's Number and Atomic Mass/Size

I'm currently rereading "An Introduction to Quantum Physics" by A.P. French, and confused myself. The text reads along the lines of (paraphrased): Making the assumption that e is equal both to ...
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36 views

Problem in derivation of Rydberg Equation

In deriving the Rydberg Equation I found that $\delta E=E_2-E_1=hf$ where $E_1$ is the energy the orbit in which the electron was and $E_2$ is the energy of the orbit in which the electron is ...
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368 views

Zero uncertainity in components of angular momentum in Hydrogen atom

It is given that L and Lz,Lx,Ly commute.(L is total angular momentum, Lx is angular momentum along x axis). So, I can simultaneously know the value of let's say L and Lz. But, if I perform huge no of ...
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How are Quantum Mechanical energy levels related to atom shells?

I'm currently taking Quantum Mechanics in school and I came across a table displaying the following in the given order: $E_n (\text{energy levels}), g_n (\text{eigen functions})$ $n \ l, [m]$ $E_1, ...
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1answer
51 views

Ground state of Beryllium (${\rm Be}$)

Why is the ground state of Beryllium (${\rm Be}$) with electronic configuration $[{\rm He}]2s^2$ is $^1S_0$ and not $^3S_1$? The state $^3S_1$ has higher spin multiplicity.
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NMR sweeping magnetic field

I am currently doing a experiment in the lab which is using a continuous wave NMR, by sweeping the magnetic field, and I am having trouble understanding how the theory works for this type of ...
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Do empty orbitals have energy?

Suppose we have the Na (Sodium) atom. It has half-filled the 3s orbital and unfilled 3p orbital. Does the empty 3p orbital have energy? also does the energy of 3p change if an electron occupy it?
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What happens to the absorbed colour on an object? [duplicate]

If white coloured light falls on an object, colours of certain wavelengths is absorbed and colour of certain wavelength is reflected. We see the object's colour as the reflected colour. Then what ...
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How to find all the possible spectral term for an atom configuration using LS coupling in the case of two unfilled subshells?

I'm not sure how to find all the possible spectral terms for an atom configuration where there are two shells not completely filled or empty. Here the LS coupling is described for 2 electrons in 2 ...
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How are line spectra explained after rejecting/improving Bohr's theory?

I learned that Bohr explained line spectra by postulating that electrons can only be at certain discrete distances from the nucleus. Later, this theory was refuted/improved by de Broglie and ...
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55 views

Collision of a photon with a quasi-free particle

What is a quasi-free proton? How does the wavelength of a photon change when it collides with a quasi-free particle, e.g. a quasi-free proton?
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How can we prove the tensor-product basis $\{|j_1,m_1⟩|j_2,m_2⟩\}$ is linearly independent? [closed]

My reference is Walter Johnson's Book Lectures on Atomic Physics (2006). Given our coupled $J$'s in the equation bellow: $$m|j,m\rangle = \sum_{m1,m2}(m1 + m2)C(j_1,j_2,j;m_1,m_2,m)|j_1,m_1\rangle|...
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3answers
114 views

What does the principal quantum number really mean? [closed]

What do principal quantum numbers actually represent? The modern structure represent that electrons do not revolve around the nucleus. It says there are no shells or orbits for electron rather there ...
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1answer
47 views

“For every line in absorption spectra, the corresponding emission line is present, but the reverse is not true”

I was studying atomic physics and read the line for every line in absorption spectra, the corresponding emission line is present, but the reverse is not true and I am not able to understand it ...
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Stueckelberg angle (rapid adiabatic passage)?

In my advanced Atomic Physics lecture the Stueckelberg angle was given by: $\theta = \arctan(-\frac{\Omega}{\Delta(t)})$ and $0 \leq \theta \leq \frac{\pi}{2}$ where $\Omega$ is the Rabi-frequency ...
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Limitations of Optical Bloch equations and the physics?

This might be too general a question. I'm looking at an OBE simulation on simple atomic evolutions while interacting with lasers. The problem is that I often take too much time to understand a result. ...
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1answer
50 views

Bohr's atoms model

Why might Bohr have been especially curious about the possible values of the angular momenta of electrons in quantum mechanics? What looks special about them?
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In what cases (precisely) are Hund's rules valid?

I can't find on any good source (such as a textbook) a precise specification about the cases when Hund's rules (especially Hund's third rule) for an electronic configuration of atom are valid (the ...
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42 views

Would it be possible that a deterministic be able to provide explanation to all the phenomena in the universe? [duplicate]

I'm not a physicist but am extremely enthusiastic about physics. My school of thought is more like Einstein and Newton (just mentioning these two since they are pretty famous) meaning that I believe ...
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1answer
34 views

What exactly happens in inelastic collisions between electrons and nucleus (Frank-Hertz experiment)?

In the Frank-Hertz experiment, electrons (inelastic ) hit atoms and excite their energy levels. What happens to the electron after it has hit (what I believe is) the nucleus? I imagine that if the ...
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Can we see emission lines in stars?

I read that stars show both absorption and emission lines. While how we see absorption lines is clear to me, I don't understand how (and when) we see the emission lines. Based on what I read in ...
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1answer
36 views

How to calculate the spin of an atom [duplicate]

If given an atom say ${^{108}_{47}Ag}$, what is the systematic way to determine its spin so that one knows whether it is a boson or a fermion?
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1answer
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Origin of hyperfine structure Hamiltonian

Our course follows a fairly similar approach to here when introducing the hyperfine Hamiltonian $\Delta H_{HFS} = A_J \vec{I}\cdot \vec{J}$ where $\vec{I}$ and $\vec{J}$ are the (total) angular ...
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Can we show that the ground state of the He atom is a spin singlet rather than triplet?

The ground state of Helium atom is a state in which the space part of the wavefunction is symmetric and the spin part is antisymmetric under the exchange of the electrons. Therefore, the ground state ...
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Literature for electronic structure theory

I could need some help regarding what path i should pursuite. I have some experince from electronic structre theory and the methods used in the field; DFT and the post HF methods I would like to work ...
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2answers
41 views

Orbital parity of simple bound states in atomic and particle physics

The parity operator commutes with the Hydrogen atom Hamiltonian. The energy eigenfunctions are parity eigenstates with orbital parity $(-1)^\ell$ which follows from the fact that $Y_{\ell m}(\theta,\...
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2answers
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Assignment of $m_\ell$ values to $p_x, p_y$ and $p_z$ states

For the orbital angular momentum quantum number $\ell=1$, there are three possible $m_\ell$ values, namely, $-1,0$ and $+1$. Which $m_\ell$ value is associated with which of the three p spates, namely,...
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1answer
42 views

Zero magnetic quantum number in Classical physics

I was reading a book on Atomic Physics where it was stated that "In space quantisation of an electron the state with magnetic quantum number $(m)=0$ was always excluded on the ground that ...
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0answers
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Atom in Radiation Reservoir (Cohen-Tannoudji formalism)

My task is to generalize the description in Cohen-Tannoudji's "Atom-Photon Interaction", p.284 from dipole only case onto forbidden transitions getting analogues of E.11 and E.13. Attempt: Took ...
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How to decouple the isotropic interaction Hamiltonian (nonzero trace) in NMR?

In NMR, one use dynamical coherent control to decouple the effective dipole-dipole interaction. Here, a spin system is subject to a strong magnetic field so that the local coupling is truncated and ...
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Why should the spherically asymmetric part of the effective potential be small in the central field approximation?

In the central field approximation, each electron is supposed to move in an effective or average potential contributed by its attractive interaction with the nucleus and repulsive interaction with the ...
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How does the Schrödinger model of the hydrogen atom take into account radiation friction?

When one first encounters quantum mechanics, he learns about Bohr's model of the hydrogen atom and one of his biggest problems - electrons were accelerating and not emitting EM radiation (which is ...
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1answer
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Release of energy during electron jumps [duplicate]

We took up the topic of particle nature of light recently.As the light is quantised when an electron jumps from higher to lower orbit it releases energy but as the energy is quantised it will release ...
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1answer
54 views

Total Orbital Angular Momentum and its relation to $M_L$ & Symmetry

I am currently working through the physics governing how electrons arrange themselves within an atom into orbitals, and I have two related questions. Note that all the atoms I talk about are ...
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State with highest energy of Carbon atom

A possible excited state of the $C$-Atom is one with a $3s$ electron: $(1s)^2(2s)^2(2p)^1(3s)^1$. One can find out that there are the 4 possibilities $^1P_1, ^3P_2,^3P_1,^3P_0$. Why is the $^1P_1$ ...