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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If there are huge gaps between atoms relatively to their size, why can we touch things? [duplicate]

Most of the volume of an object actually consists of empty space rather than molecules. So why don’t solid objects move through each other?
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How is two-level optical transition in a spin 1 system affected by the third level?

Suppose you have a spin-1 system. Let us resonantly drive the transition between any 2 levels (say 0 1 transition). How would the the presence of the third level (-1) state affect this transition? We ...
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Help understanding the origin of scattering phase shift

I'm having a conceptual problem. The time-independent Schrodinger equation for a continuum state $\psi_{k, l}(r)$ is given by $$ 0 = \left( - \frac{\nabla^2}{2} + v(r) - \frac{k^2}{2} \right) \psi_{k,...
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Magnetic moment of carbon

I read recently the magnetic moment of carbon is zero. I am surprised how is this possible because the electronic configuration of it is $1s^2 2s^2 2p^2$. So we have two unpaired electrons here. I'll ...
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Electronic quantum jump time = transition time = lifetime?

Naively I assumed that an electron would sit in an excited state (in the shell of an atom) having some stochastic lifetime, so nothing changes and suddenly the electron would jump back into the ground ...
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Pressure broadening in absorption spectra

I was reading about pressure broadening for atomic spectra. What I can't understand is why it is important in absorption spectra if the collisions affect only the lifetime of the excited states. It ...
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Do photons and gravitons emitted in quadrupole atomic transitions have the same momentum?

A transition of an electron from orbital $3\text d$ to $4\text s$ produces photons and in small chances gravitons ($\Delta l= \pm2$) through quadrupole transitions. In 2 atoms, if one does this ...
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How to understand the hydrogen energy level and its wave function?

I have difficulty to understand this Hydrogen atom's energy level and its wave function. My difficulty is regarding the hydrogen atom itself, not the energy level and the wave function their selves, ...
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When is a free electron caught by the ion? [closed]

Some questions about ion and a free electron heading towards it and building (or not) of atom. Must the free electron pass through the electron cloud area of the subsequent quantum level in order to ...
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Two electrons in the ground state

I've been introduced to multiple particle systems in quantum mechanics, and in the case of the $2$-electron system, I'm facing this massive confusion. In the ground state of a $2$-electron system, you ...
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X-Rays and UV Penetration Dichotomy Relative to Visible Light (Shorter Wavelength but opposite penetration)

My understanding was that relative to visible light, ultraviolet tends to be more strongly absorbed by materials because the higher energy photons are likely to be able to interact with the material. ...
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Why do X-ray telescopes have to be in space?

I have read this question: For x-rays the (HUP limit) Δx becomes smaller than the distances between the lattice distances of atoms and molecules, and the photon will interact only if it meets them on ...
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Can an electron jump to a higher orbit with an energy that is only a little less than the theoretical requirment? [duplicate]

I understand that electrons can possess only discrete amounts of energy so if an electron in an atom has to jump from a lower orbit to a higher orbit it will require a discrete amount of energy to the ...
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Does all the atoms have same mass with respect to their molar mass ? Is there any factor that increases its inertia? [closed]

Does all the atoms have same mass (with respect to their molar mass). For example: 1 mole of Uranium 234 has a gram molecular mass of 234 grams, But is there any factors that increases its mass ?. ...
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Total number of states for a two electron system

Let's say, I have the following electronic configuration, $1s2s$, and I'm trying to find all the possible states. By looking at the configuration, it is obvious, that in the $|l_1,m_{l_1},m_{s_1},l_2,...
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Triplet states and Fine Structure

If we have a system, with total spin angular momentum given by $S$, then we have spin multiplicity equal to, $2S+1$. This spin multiplicity basically tells us the different spin states, this system ...
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Atomic levels energy

While reading about $LS$ coupling, and the fine structure of atomic energy levels, of various electron-electron configurations, I came across two different representations. For example, if we consider ...
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Degeneracy of Atomic energy levels

I've started reading about the atomic spectra and came across LS coupling and so on. However, I have a doubt regarding the entire thing. Let us say, we have 2 electrons, say $4p-4d$ state, and we are ...
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Does changing energy level of electron in an atom has time duration? [duplicate]

In quantum mechanics electron in an atom is described by the wave function of probability. When the electron changes level the wave function changes to another. Is the changing electron level when it ...
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Calculating the magnetic field of the Proton in Spin-orbit Coupling in Hydrogen Atom

I was reading in the Book: Introduction to Quantum Mechanics by David J. Griffiths. In chapter Time-independent Perturbation Theory, Section: Spin -Orbit Coupling. I understood that the spin–orbit ...
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Is it possible to calculate the fine structure constant?

Can this constant be derived mathematically or is derived entirely from experimental data?
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Is the relativistic Dirac equation the most accurate way to calculate energy levels?

I am curious about the current state of the art of calculating energy levels for atoms? Is there a better way to do this now?
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1answer
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Has the atomic radius been experimentally verified?

In the answer to a previous question it was asserted the Bohr radius was upheld by the Schrodinger wave function to be the most probable size for the atomic radius of 1s hydrogen. Has the radius of a ...
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During promotion of electron in $3p$ orbital before hybridisation, why does it get promoted to $3d$ orbital and not $4s$?

During the hybridization of certain elements such as phosphorus during the formation of $\rm PCl_5$, the atom first gets changed to the excited state. In the case of $\rm PCl_5$, the paired electron ...
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Why is proton emission mode in nuclear decay so rare?

I was reading Atomic Structure and Spectral Lines by Arnold Sommerfeld for historical purposes. This book is a classic from the 1920s. He writes If, in accordance with the sense of Prout’s hypothesis,...
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Why is the law of reflection true?

When a bunch of photons strike a surface then they get absorbed by the electrons on that surface which then starts oscillating and thus re - emit some photons but they do it in the same plane as that ...
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1answer
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What is the emission spectra of electrons under the Zeeman/Stark effect?

As the Zeeman effect/Stark effect lead to a change in the energy levels of orbital electrons in relation to their spin, similar to hyperfine transitions, I was wondering what the emission spectra of ...
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Can electron confinement systems display hyperfine transitions?

Just as Quantum dots can display the energy transitions characteristics of electron in a conventional hydrogenic atom to give emission tunability, can it and other similar electron confinement system ...
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The color of an object, the atom releasing the photon back

I have a question about why the color of an object is as it is. This is something I am wondering about after watching episode 5 of the tv-series Cosmos from 2014. From what I understand a blue object ...
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1answer
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How is atomic time defined in Hartree units?

As in Planck units, I believe Hartree units have a fundament unit of time, Atomic Time, something like $2.4188843265857(47)×10^{−17}$ s. My question is what exactly is it that happens in this time? ...
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What is the lowermost energy a photon can be emitted by hyperfine transitions?

The 21 centimeter Hydrogen line comes from the hyperfine transition from its one electron, which leads to a photon with the energy of $2.24\times10^{-25}$ joules being emitted. Can lower energy levels ...
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1answer
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Location of Orbital inside atom

So, I was am having a hard time understanding the location of an orbital inside an atom. I read that: Within each subshell, there are orbitals. This gives the final location of where electrons reside ...
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Do two atomic nuclei interact with each other? [closed]

I am exploring physics through youtube documentaries and wikipedia mostly. I do not understand though if two atomic nuclei ( two atoms with a nucleus) interact with each other. I can think of two ways ...
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Why do electrons in an atom occupy a well defined energy state? [duplicate]

I was trying to answer a very simple question: how does QM resolve the classical physics paradox of the electrons falling inside the atomic nucleus by emitting EM-radiation. Well, in short, the answer ...
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1answer
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How are the wavelengths calculated to hold and combine atoms in optical trapping?

I am reading this article of scientists who combined individual atoms using optical tweezers. One optical tweezer used a 700 nm-wavelength light to hold the sodium atom while the other optical ...
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How to correctly use rotating frames in Schrodinger equation for Jaynes-Cummings Hamiltonian?

Jaynes-Cummings Hamiltonian describes the system of an atom interacting with light. $$\hat{H}=\hbar\omega_{light}\left(\hat{n}+\frac{1}{2}\right)+\hbar\dfrac{\omega_{atom}}{2}\left(|e\rangle \langle e|...
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The most precise analytic solution of the hydrogen energy levels [closed]

Consider the problem where we want to calculate the energy levels of an electron in a hydrogen atom and we want to find the most precise analytic (i.e. a closed-form solution) solution that matches ...
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Why is there no atom-atom interaction term in the Jaynes-Cummings Hamiltonian?

The Jaynes-Cummings Hamiltonian for a single mode interacting with multiple atoms is $$H/\hbar = \sum_{j=1}^N \omega_{\text{atom},j}\sigma_{+,j}\sigma_{-,j} + \omega_{\text{field}} a^\dagger a + g/\...
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$LS$ vs $JJ$ coupling hamiltonian

While studying $LS$ coupling, I came across the fact that it is only applicable for lighter atoms, and the perturbation term in the hamiltonian is given as: $H_2 = A_{ij} \vec{L}.\vec{S}$, where $A_{...
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1answer
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Confusion regarding addition of spin and $LS$ coupling

I've recently studied the addition of angular momenta in quantum mechanics, and faced a massive confusion during the addition of spin, in a two-electron system. When adding the two spin-1/2 electrons, ...
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Which type of material would I have to study to get a deep understanding of the ionization phenomenon?

I've been collecting basic information about the phenomenon of ionization. I know what it is and its sources and types (as well as the type of particles that can cause it). However, it is my goal to ...
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Experimental electron configurations of copper and chromium and Aufbau principle

I was reading the Aufbau principle article on Wikipedia Aufbau principle after seeing so many student questions on Chem SE asking about writing electron configurations. Every general chemistry student ...
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Electron configurations beyond hydrogen

In 1990, the Journal of Chemical Education (American Chemical Society) published a little bit controversial article titled "The nature of the chemical bond—1990: There are no such things as ...
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Coulomb potential singularity

When reading Gravity and Strings book by T. Ortín, I have come up with the following paragraph: "if we solve Maxwell’s equations in vacuum imposing spherical symmetry and staticity, we find the ...
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1answer
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Is there a highest possible atomic number?

I know that atoms with higher atomic numbers tend to become more and more unstable and decay quicker the higher the atomic number goes. Is there a limit to this where the time it takes for the atom to ...
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2answers
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Where does the kinetic energy of recoil in hydrogen come from?

I came across a rather simple question asking the recoil speed of hydrogen atom when it releases photon while electron goes from n=2 to n=1. The photon emitted will have energy released during the ...
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Thermodynamically speaking, in the absence of proton decay will matter decay into Iron-56 or Nickel-62?

I understand there are already questions with similar premises but neither of them actually have the answer to the question I have. Thus I'd like to split my question into two more specific sub-...
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Does the total orbital angular momentum $L^{2}$ commute with the atomic Hamiltonian?

I would like to know if the total orbital angular momentum $\mathbf{L}^{2}$ commutes with the Hamiltonian of a many-electron atom when we consider the interactions between the electrons. $$H = -\frac{...
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Dirac equation vs relativistic Hamiltonian

The fine structure can be derived by considering the relativistic Hamiltonian and also adding corrections for magnetic fields, etc. For hydrogen these effects are small, which makes it easy to obtain ...
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First excited state of $\rm He$ atom

The ground state of the Helium atom corresponds to $1s^2$ that in spectroscopic notation can be written as ${}^1S_0$. I'm trying to find the first excited state. It's clear that one electron should be ...

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