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, unless otherwise stated, for the purposes of this discussion it should be assumed that the term atom includes ions.

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Do-It-Yourself physics experiment [closed]

Is there any simple experiment in physics of the first half of the 20th century I could do at home? I tried to make a cloud chamber, but it didn't work at all... A spectrometer from a CD disk is ...
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State Evolution in Cavity QED

Part 1 $\newcommand{\ket}[1]{|#1\rangle}$ If a general state of a 2-level atom can be represented by: $$\ket{\psi} = \cos(\frac{\Omega t}{2} + \phi)\ket{g} + \sin(\frac{\Omega t}{2} + \phi)\ket{e} $$ ...
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26 votes
5 answers
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Does gravitation really exist at the particle level?

As I understand, we usually talk about gravity at a macro scale, with "objects" and their "centre(s) of mass". However, since gravity is a property of mass generally (at least ...
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Collision of $\rm H$ atoms [closed]

The question is: Two $\rm H$ atoms in the ground state collide inelastically. The maximum amount by which their combined kinetic energy is reduced by__________ well in this question I solved it ...
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1 vote
2 answers
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Why lead plate was used in Rutherford's gold foil experiment?

I have read that lead plate is used to concentrate the beam of alpha particles which are being directed towards the gold foil as it is a heavy metal. But there are other heavy metals like manganese, ...
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Photon polarization with respect to quantization axis

I really struggle to understand $\pi$, $\sigma^{\pm}$ transitions. I am aware that I need a quantization axis to define my angular momentum levels $m_z = \pm\hbar m$. I am also aware that $\Delta m = ...
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2 votes
1 answer
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Is muonic hydrogen atom or exotic hydrogen atom more stable

According to Bohr's model of hydrogen atom, the energy of the electron is given by: $$E=\large-\frac{me⁴}{8εh²n²}$$ So if we replaced the electron with a muon whose mass is ~200me, will that new atom ...
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About why electrons in atom don't radiate(considering wave nature also) [duplicate]

It's said in textbooks that electrons won't radiate and fall into nucleus because matter wave of it's form a standing wave but could somebody explain why being a standing wave it doesn't radiate, even ...
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Which neutral atom-based quantum sensor is hardest to build/operate?

I am currently going through the presentation, "Sensing with neutral atoms", by Grant Biedermann. I understand that, according to the talk, there are a large number of different sensing ...
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Can someone please explain energy of electrons in Bohr's model?

Energy of and electron is $$E = \text{kinetic energy} + \text{negative of potential energy}. \tag{eq-1}$$ But energy of electron in the $n$th orbital is also $$E = -\frac{13.6}{ n^2} \tag{eq-2}$$ ...
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How is the internal energy changed if an atom is charged?

I read this statement from an exam: A neutral carbon atom gains 4 electrons, this atom has a higher internal energy after the addition than before. I am not sure whether it is correct, in particular, ...
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How does $s$ subshell not have a node in the center despite the nucleus being there?

In most images of $1s$ subshell I see that there's no node shown at the center, and even the formula $n-\ell-1$ gives 0 as the answer. But, isn't the nucleus experimentally proven to be at the center? ...
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1 answer
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How does parity work for the electric field and electric dipole and electric quadrapole transitions?

It is known that the electric field is a (polar) vector and is odd under parity. Likewise, when an atom undergoes a dipole transition its parity must flip because the dipole electric field acts like ...
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Splitting of $sp$-System due to LS coupling

How do I explain the splitting of $sp$-system due to LS interaction? I think it is due to the magnetic field created due to the orbital motion of the electron, and that magnetic field splits the ...
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3 votes
2 answers
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What is the mechanism of transparency of EM?

What happens in transparent materials? Do their molecules oscillate with the same frequency as the EM wave and then reemit in the same direction? Or the light goes through meshes in the bulk?
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What is the single active electron approximation?

I keep stumbling upon this approximation while reading papers on atomic physics, but I couldn't find a proper description of what it is in any textbook or pedagogical paper. The closest I could find ...
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In relation to the correspondence principle, what happens when the orbital magnetic quantum number $m_\ell$ is very large?

If for each value of the orbital quantum number $\ell$ there are $2\ell+1$ possible associated magnetic quantum numbers $m_\ell$, and they are interpreted as the only allowed orientations that the $...
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In Helium, why does more tightly bound mean the electrons are further apart?

In helium, the triplets ($S=1$) are lower in energy (more negative) than the singlets $S=0$. One reason given by my lecturer is that in a triplet the spins of the two electrons are the same, then by ...
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Are atoms still unstable in 4 spatial dimensions when the physical size of nuclei is accounted for?

Per this answer, depending on a dimensionless parameter hydrogen atoms in 4 spatial dimensions can be either unbound (i.e., nonexistent), stably bound dependent on boundary conditions, or unstable ...
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2 votes
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Spin-Orbit perturbation theory

I'm trying to use pertubation theory to calculate the energy shift due to spin-orbit interaction between the electron and proton in the hydrogen atom. I'm stuck on how to proceed as this hamiltonian ...
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1 answer
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Charge in atoms in bond

Let us think of a covalent bond between two atoms $A$ and $B$. Since in covalent bond,sharing of electrons take place, valence eletrons of one atom behave as the electrons of the other atom. So since $...
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How much faster does induced fission in a typical reactor occur than spontaneous fission in nature?

I know that the half-life of Uranium-235 is about 704 million years, but... That includes alpha and beta radiation as well as spontaneous fission, though... Also, I presume the 'spontaneous fission' ...
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Are the shapes of atomic orbitals direct consequence of the Schrödinger equation?

I am trying to understand whether the shapes of the orbitals are inevitable given the standard model. They would probably change if we change the fine tuning of the fundamental physical constants, ...
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Energy Separations in Term Scheme of Helium

I have been given the following term scheme for Helium: The bottom level corresponds to the ground state $1s^2$ term symbol while the 4 above it are the term symbols of the $1s^12p^1$ excited state. ...
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Magnetic moment of current loop

From what I have learnt, the magnetic moment of a current carrying loop is $$\pmb{\mu} = NI \mathbf{A}.$$ But what is written in this book Modern atomic and nuclear physics by Fuzia Yang, I am not ...
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4 votes
1 answer
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Why do photons: "have to give all their energy or none at all", in photon-electron excitation interactions? [duplicate]

Consider the following A-level physics question: The transitions between energy levels shown in Fig. 1 can occur when electrons in the atom are excited. This can happen when a photon interacts with ...
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Rutherford Model of Atomic nucleus [duplicate]

I was studying the Rutherford Model of Atomic Nucleus. One of its drawbacks was it ignored the fact that electrons in circular motion are constantly radiating energy and will eventually collide with ...
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-1 votes
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Why is it when an atom gains a proton it is said to become an 'atom' of a different element?

My confusion lies in that the number of protons in the nucleus will increase but is the number of electrons assumed to automatically follow suit such that the result is a neutral atom with equal ...
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How can an $n=25$ Rydberg state exist in a solid? What does the wave function look like?

Phys.org's April 15, 2022 Ancient Namibian stone could hold key to future quantum computers begins: A special form of light made using an ancient Namibian gemstone could be the key to new light-based ...
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3 votes
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Canceling the remaining time-dependence in a "cyclic" Hamiltonian for which rotating frame transformation (RFT) fails?

Question: Is there a transformation or simple approximation to use to cancel the time-dependence in a Hamiltonian of form $$ H_{G} = \sum_{(m,n)\in E,\ m<n}\Omega_{mn} e^{-i\Delta_{mn} t} |m\rangle\...
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Selection rules for electronic transitions when noble gas atoms collide

The selection rules of atoms that are alone are useful for determining whether there can be certain radiative transitions, or which transitions are more likely than others. For example, for small ...
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Is the $(1s)(2s)$, $S=1$ excited Helium state metastable?

I am reviewing properties of atoms, and I am trying to understand the concept of forbidden transitions better. My understanding is mostly at the level of Griffiths quantum mechanics. My motivation is ...
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Moseley's law for $K_\beta$

In a certain problem, it started out by giving a graph between $\nu$ and $Z$ .The graph resembled $y=k(x-1)^2$(the constant is unknown ,that is we only know the vertex value,not the slopes). At the ...
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Energy transfer and electromagntism

How is kinetic energy from one moving macroscopic object to a stationary object is transferred at a particle level? Is all energy transfer that exists an effect of electromagntism at the particle ...
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6 votes
1 answer
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Large difference between the atomic sizes of uranium and thorium

According to Villars and Daams [Journal of Alloys and Compounds, 197 (1993) 177] the atomic volume of U is $2.073\times10^{-2}\,\mathrm{nm^3}$, whereas that of Th is much larger, $3.295\times 10^{-2}\,...
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Electronic bands and Aufbau principle

In atomic theory there is Aufbau principle stating (Wikipedia) The rule states that for a given electron configuration, the lowest energy term is the one with the greatest value of spin multiplicity. ...
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Change in photon production rates due to finite temperature / a QED plasma?

I have the following question: In a QED plasma, the photon technically gains a "mass" due to a change in its dispersion relations. I was wondering, if the photon also acts as massive during ...
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2 answers
101 views

How were the electrons, protons counted in an atom?

The title says it all! In high school I remember it being taught as a religion, I had to believe the count (hydrogen has 1 proton, carbon has 6 etc...) , but how can I be sure I was told the truth?
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3 votes
1 answer
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What would happen if an atomic bomb exploded on a nuclear power plant?

Would the effect be different than if the nuclear power plant were bombeb with traditional explosives? Would the atomic bomb neutralise any potential radioactive effect of the obliteration of the ...
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Can the lifetimes of excited states be calculated (specifically for $4^3D_{5/2}$)?

How do I find the lifetime of the excited state $4^3D_{5/2}$ for $Rb^{87}$? I know the lifetime of $5^2P_{3/2}$ (which is 26.24 ns), and according to this link, the spontaneous emission rate is ...
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1 answer
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What is the non-relativistic differential equation for the helium atom?

I understand that the Schrodinger Equation for the hydrogen atom is $$E\Psi=-\frac{\hbar^2}{2m}\nabla^2\Psi+V\Psi$$ with $$-\frac{\hbar^2}{2m}\nabla^2\Psi+V\Psi$$ being the Hamiltonian and I ...
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2 votes
0 answers
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How does the concept of activation energy work for interatomic collisions?

Say we have a Lennard-Jones -esque potential for colliding atoms. Say this potential admits a bound state at a lower energy than the kinetic energy of the colliding atoms. So forming this molecule ...
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How do the cusp conditions for helium atom translate from $(r_1, r_2, r_{12}) \to (r_1, r_2, \Theta)$?

While trying to make a Helium atom ground-state solver, I encountered the Cusp conditions initially derived by Kato et al. and then generalised by C. C. J. Roothaan and A. W. Weiss $$\lim_{r_{i} \to 0}...
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2 votes
1 answer
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A question regarding excitation of electrons in atomic orbitals

In Bohr's model of an atom, the formula used to find the energy between the 2 orbits and wavelength of emitted photon was valid only for single electron species like hydrogen.In the case of a multi-...
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What did the "cloud of positive charge" consist of in the Plum Pudding atomic model? [closed]

Did this cloud have mass? Was it just an electric field or was it a particle, or something else? If it was an electric field, how was it created and how did it maintain its form? From my understanding,...
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2 votes
3 answers
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I’m studying black body radiation and I can’t understand how it produced due to the vibrations of atoms

So,in my physics school book it’s written that atoms don’t radiate as long as they are stable ”in the ground state” I can’t understand how I mean isn’t all the bodies radiate as long as they have a ...
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1 answer
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Transition rate for electrons between two energy level

I am considering spontaneous emission between two energy eigenstates, $e \to g$, at finite temperature. I would imagine that the rate of transition depends on the occupancy of the initial and final ...
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1 answer
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What makes carbon atomic structures stand out from other elements in terms of their properties?

Since lots of materials with some remarkable properties are some form of carbon structures: Incredible strength of graphene is often explained by it having a hexagonal atomic lattice. Hardness of a ...
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Does the $3s$ orbital contain the $2s$ orbital?

The following image is in my introductory chemistry textbook: It seems to imply that the $3s$ orbital “contains” the $2s$ and 1s orbital. That is, a $3s$ electron could find itself in a region of ...
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2 answers
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Hamiltonian of wavefunction of $2s$ and $2p$ orbitals

I have recently developed an interest in the analysis of a certain problem in atomic chemistry regarding the energies of $4s$ and $3d$ orbitals, and I observed that even though the wavefunction of $2s$...
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