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

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Is the direction of the Coulomb force at short distances indeterministic?

Suppose we have two electrons that apply a Coulomb force on each other. At large distances, we can consider the two electrons as point charges and the direction of the Coulomb force would be on the ...
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Branch of Physics that Examines Atoms Relationships

Is there a specific branch of physics that can examine and calculate the strengths of atomic or molecular bonds and predict how they are going to break, putting into consideration the surrounding ...
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When a diatomic ion dissociates, how does the electron density on each atom change?

Let's say, we have a fluorine molecule (F2), and we take 3 electrons from it, so now its bond starts to stretch, and at last the bond breaks and the two atoms are farther and farther away from one ...
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Zeeman effect - accidental degeneracy for high fields?

For a low level field, the energy splittings are given by $$\Delta E(L, S, J, m_J) = \mu_B m_j g_L B_z$$ where $g_L$ is a g-factor. This predicts a separation into $(2J+1)$ levels, so completely ...
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Why, precisely, do three elements in a row (iron, cobalt, nickel) show ferromagnetism, but not the elements below them on the table?

The same is true for Neodymium, Promethium and Samarium, right? But like the first three, they are consecutive, not above and below each other. Somehow only elements in those two ferromagnetic 'hot-...
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How does the collision between two atoms work?

Considering the quantum mechanical model for an atom, what exactly happens when two atoms (say, two Ca2+ ions in a Brownian motion) collide with each other? As I know, this collision is not like a ...
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what is the cause of the first atom moving in moving?

I'm a computer student and I know nothing about physics and physics.stackexchange, so if I did something wrong, tell me to correct it (for example tagging). and ...
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An alpha particle with kinetic energy K=0.50 MeV is deflected through an angle of θ=90∘ [closed]

by the coulomb field of a stationary Hg nucleus. The least curvature radius of its trajectory and the minimum approach distance between the particle and the nucleus are respectively:A)0.56 pm and 0.23 ...
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Orbital angular momentum quantum numbers - subtracted?

Reading Griffiths' Quantum Mechanics. We have the electronic confirmation of Carbon as $$(1s)^2 (2s)^2 (2p)^2$$ in the ground state. He says There are two electrons with orbital angular ...
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How to use Dyall basis sets for radial wave functions?

I have found the dyall basis set coefficients on the homepage http://dirac.chem.sdu.dk/basisarchives/dyall/ Does anyone in the forum has experience for using for example the "5p" basis set? I only ...
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Basic labeling of the hyperfine structure of $^{133}$Cs

I am practicing some questions in preparation for an upcoming exam and the following has me stumped: The D2 line of $^{133}$Cs involves transitions between the ground state $6S_{1/2}$ and the ...
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What are reasonable sets of theoretical values for mass and uncertainties of quantum particles

So I have equations of $\Delta x(t)$ that involve the uncertainties of the positions of two masses at $t = 0$, uncertainties in momenta, and the masses of the particles. The equation is complex enough ...
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Is making nuclear bomb using natural uranium possible?

I know that the critical size of natural uranium metal with graphite moderator is about 27 tons "oak ridge graphite reactor". for comparison highly enriched uranium have only 17 kg critical size with ...
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Temperature dependence of emission spectra?

Since an emission spectra represents electrons moving back down to different energy levels and releasing a photon with the energy difference, wouldn't the emission spectra of a star be temperature ...
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Actual width of surface charge layer in conductors

In routine calculations we consider the width tending to zero and instead let volume charge density become a one-dimensional (radial) delta function. Thinking classically in lieu of quantum reality, ...
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When a valence electron is excited, how fast does it move from ground state to excited state?

Imagine an atom with a valence electron becomes excited and the electron moves to a higher orbital, is this transition between ground state and excited state at speed of light? If so, since it is not ...
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Empty space inside of atoms [duplicate]

Since most of the space between the nucleus and electron is empty space is that space in a vacuum? I’ve not seen any info on this online or in textbooks does anyone have anything on this?
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If measurement of state of a photon yields some result R1 out of some mixed states then R1 is likely be the result just after the measurement?

In a popular introductory QM textbook, I came across this experiment which measures the state of polarization of the photon (light) by passing it to some experimental setup. Suppose the incident ...
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What does the Heisenberg principle actually mean? [duplicate]

As far as I can understand, the Heisenberg principle limits the possibility of calculating the exact position and momentum of electrons, as the light we use to observe it changes it's velocity. But ...
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How did Goudsmit and Uhlenbeck figure out the electron has spin $\frac{\hbar}{2}$?

Most stuff I read online says that to explain the Anomalous Zeeman Effect they had to assume the electron's gyromagnetic ratio is $\frac{-e}{m}$ instead of the classical $\frac{-e}{2m}$. But, since ...
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Vibrational states in anti-bonding orbitals

In all texts online, first the Born-oppenheimer approximation is used to split the wavefunction of a diatomic molecule (homonuclear considered only here) to that of a nuclear relative motion, and a ...
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Does helium have any accidental degeneracies?

Does helium have any accidental degeneracies, i.e. are there reducible eigenspaces of $$-\Delta_1 - \Delta_2 - \frac{2}{r_1} - \frac{2}{r_2} + \frac{1}{r_{12}}~?$$
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Lee and Yang's 1956 Paper

I've been reading Lee and Yang's paper that looks into the possible of parity violation. You can find it here: A Question on Parity Conservation in Weak Interactions. And they say This phenomenon ...
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How to work out spontaneous decay rate for E2, M2, E3 and M3 transitions?

The types of transitions allowed in a hydrogenic atoms are listed here. They range from the known electric dipole (E1) and magnetic dipole (M1) transitions, to electric quadrupole (E2) etc... I want ...
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Rutherford's and Bohr's model of atom [duplicate]

Rutherford's model of atom was ruled out because it failed in explaining stability of an atom. Since any particle that is accelerating continuously emit radiation. And in case of an atom eventually ...
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Angular momentum and Zeeman effect

Supposing an Alkali atom positioned in magnetic field in $z$-axis. I understand linearly polarized laser propagating in $z$-axis can induce $\sigma$ transmission. But I could not figure out how laser ...
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Plasma inside deuterium spectrum tube?

Hullo, In a deuterium spectrum tube there is a thin capillary in the middle (see picture) that glows purplish sort of. Now, I wonder what this glowing part actually consist of? Is it a completely ...
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Self-interaction in spin-orbit coupling?

In spin orbit coupling, in an atom motion of electrons about nucleus generates magnetic field and we consider this field to interact with magnetic moment of electron. It sound strange as in ...
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281 views

$2s\rightarrow 1s$ transition in hydrogen

I would like to understand how the parity-violated interaction between electron and proton can provide the photon with circular polarization in the $2s\rightarrow 1s$ transition with single photon ...
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1answer
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Necessary photon energy for electronic excitation

What happens if a photon incident on an atom has greater energy than the difference of energies between successive energy levels corresponding to electronic excitation(say between ground state and ...
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Semi-classical Hydrogen Atom Angular Momentum under Magnetic Field

Suppose we have a semiclassical hydrogen atom in its ground state at the x-y plane with the proton being at the origin. Let there be a magnetic field $\vec{B}=B\hat{z}$. By deriving the orbital ...
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1answer
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Thomson's Plum Pudding and Rutherford's scattering [duplicate]

Why did Rutherford's scattering experiment disprove the plum pudding? Assuming a gold-atom to be a large homogeneous ball and hitting it with small homogenuous $\alpha$-balls should lead to the ...
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Why does the read-out efficiency increase when coupling an atomic ensemble to an optical cavity?

I went through a paper where it mentioned that the read-out efficiency of a quantum memory would be increased by coupling the atomic ensemble with an optical cavity. I think rydberg atoms were used to ...
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Relation between quantum numbers $j$ and $\ell$

I'm given the following problem: "Consider an atom with orbital angular momentum $l$. What are the possible values of the total angular momentum quantum number $j$? Treat the case of $\ell = 0$ ...
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How to calculate the transition energy between $^2P$ to $^2S$ and $^2D$ to $^2S$ for sodium?

It's been known how to calculate the Zeeman effect. However how to calculate the transition energy between $^2P$ to $^2S$ and $^2D$ to $^2S$ for sodium($Z=11$)? ($^2P$ here meant term symbol ignored ...
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Probabilities in non-stationary states

I'm confusing myself. Let's represent some state in the eigenbasis for Hydrogen: $$|\psi\rangle = \sum_{n,l,m}|n,l,m\rangle\langle n,l,m|\psi\rangle.$$ Now denote the initial state by $\psi(t=0)\...
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Selection rules with the Wigner-Eckart Theorem

Working in the $|\alpha, j,m_j\rangle$ basis (denoting all irrelevant quantum numbers by $\alpha$), the Wigner-Eckart theorem tells us that the elements of a rank $k$ spherical tensor $T_q^{(k)}$ can ...
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Why does a stable orbit of $H$ atom contain an integer number of de Broglie wavelengths? [duplicate]

I was trying to understand why a stable orbit of a hydrogen atom has to satisfy that the orbit length must be a multiple of de Broglie wavelength. I have seen some related questions like This. But ...
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Why does electron $(-)$ keep rotating round the nucleus $(+)$ even they are attracted? [duplicate]

I'm a secondary school pupil, my physics textbook discussed atomic physics without deep details because we are young boys, to explain electron motion we first learn about rotational motion. The main ...
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LS coupling vs jj coupling as extreme cases - related to the relevant vector sum model

The difference between light and very heavy atoms reflects itself in these two schemes. My question is why one scheme for the vector sum is necessarily the right & suitable sum model for one case, ...
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Is the $2p\rightarrow2s$ transition possible?

Selection rules in one electron atoms are: $\Delta n=$ any $\Delta l=\pm1$ $\Delta m_l=0,\pm1$ $\Delta s=0$ Parity must change Under strong spin orbit interaction: $\Delta j=0,\pm 1$, but $j=0\...
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Spectroscopic notation for $As$

I’m wondering if I’m approaching hund’s Rules for Arsenic correctly (Ar): (Ar)$(3d)^{10}(4s)^{2}(4p)^{3}$ I started with HR1: Maximize the spin. I have 6 orbitals so I can put one electron in the ...
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Rabi flopping via density matrices?

Is it possible mathematically to derive Rabi flopping in a two-level atom with the machinery of density matrices? If so, how would one go about it? In particular, let the Hamiltonian of the system be ...
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Solving density matrix in a two-level atom

I'm working through some parts of Stephen C. Rand's Lectures on Light: Nonlinear and Quantum Optics, specifically sections in which he works with density matrices. In several places he makes ...
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J-levels in jj-multiplet structure for 2 electrons with l=2

In E. M. Pärschke and R. Ray, Spin-orbit interaction in Sr2IrO4 :jj vs LS coupling schemes, available here, on page 2 the following diagram is pictured: According to my understanding, $j_1$ and $...
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Magnetic force and work done [duplicate]

If magnetic force do no work at all then how do magnets attract or repel each other?
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Why do nodes exist in wavefuncions of electrons? [duplicate]

Nodes are points in space around a nucleus where the probability of finding an electron is zero. However, is there a reason for the existence of Nodes? I'm looking for an intuitive explanation if ...
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Are all collisions involving photons and electrons elastic?

In my textbook it asks me to calculate the energy gained by an electron that scatters an incoming x ray through a given angle. Using the Compton scattering equation you can work out the change in ...
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How is Bragg's Law related to the Phenomenon of Diffraction?

As far as I understand, bragg reflections is a geometric result which says that parallel x ray beams that are incident on atomic planes will constructively interfere at specific angles. Where does ...
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Reflection of a mirror concerning angle and wavelength

Mirror has a silver coating which helps it reflect all colors of light. From my classical understanding, silver atoms reflect light by absorbing it and then emitting it at the same angle to the normal....