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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2answers
204 views

What exactly is the “energy” of an orbital?

In chemistry, I have come across the term " energy of orbital" several times but I am unable to understand it from a physics point of view. 1) is the energy of an orbital the electric ...
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What do atomic orbitals represent in quantum mechanics?

I am learning the basics of quantum mechanics and am familiar with the Schrödinger equation and its solution, but I was confused about what the familiar atomic orbital shapes represent? Do they ...
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AC Stark shift clarification

I think I am a bit confused about the AC Stark shift effect. Assuming we have a 2 level system with energy difference $\omega_0$ and we apply a laser of frequency $\omega$ and Rabi frequency $\Omega$. ...
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70 views

Why does perturbation theory work for helium atoms?

I saw the following argument for calculating the energy levels of a helium atom. First, ignore the Coulomb interaction term between two electrons. For this simplified model, we have the same solutions ...
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How are atoms split into subatomic particles? [closed]

How are atoms split into subatomic particles such as neutrons, protons or electrons? And I mean in the practical sense, not just theoretically
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6answers
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What actually is white light?

I was studying spectra and suddenly a question popped up relating to the absorption spectra. When we say that the electron absorbs certain wavelengths(photons) so we are implying that white light is a ...
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46 views

Why $d,f$ electrons are more localized than $s,p$ electrons?

I’m reading Assa Auerbach’s Interacting electrons and quantum magnetism. In 1.3, it says In contrast, transition metals and mixed valence rare earth compounds contribute $d$ and $f$ electrons to the ...
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1answer
51 views

Origin of Spin-Orbit Interaction

The spin-orbit interaction in a hydrogen atom is often explained as arising from an interaction energy $U=-\mathbf{m}\cdot\mathbf{B}$ where $\mathbf{m}$ is a magnetic moment due to the electron’s spin ...
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1answer
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Do LCAO wavefunctions form a basis for states of diatomic molecules?

I've been trying to gain understanding for diatomic molecules by visualizing the electron wavefunctions of their ground and excited states. As, for this purpose, quantitatively correct energies, ...
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Xray atomic Binding Energy in Isotopes?

Does Xray atomic level energy value change in isotopes? Is the electron binding energy the same for same element isotopes? Do you know a reference?
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Cohen-Tannoudji Complement C1: kinetic energy derivation

In Complement CI of Cohen-Tannoudji's Quantum Mechanics, the Heisenberg uncertainty relation is used to derive the ground-state energy and approximate orbital radius in a Bohr model of the hydrogen ...
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What do you think of the idea of measuring macroscopic Special Relativistic-kinematic time dilation by placing atomic clocks onto moving dollies?

We first attempt to synchronize two stationary clocks placed apart, and we assume we succeed using the Einstein synchronization convention. Then, we run a third clock along a dolly at a constant speed....
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Theoretically maximum atomic number and its stability?

Is there a theoretical maximum to the atomic number? Is it possible to reach $Z = 150$ or $Z = 200$? I am not really asking about our experimental, but theoretical limitations that possibly prevent us ...
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1answer
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Is it possible that the energy of the energy eigenstates $|LSJM_J\rangle$ depend on $M_L$ and/or $M_S$?

If a many-electron Hamiltonian $H$ commutes with ${\vec L}^2, {\vec S}^2, {\vec J}^2$, and $J_z$ but not $L_z$ and $S_z$, the energy eigenstates are designated by $|LSJM_J\rangle$. Since there is no ...
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1answer
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Confused about Ramsey technique

Assume we have a 2 level system with the frequency between the 2 levels $\omega_0$ and ignore the lifetime of the upper state. In order to measure the transition frequency using Ramsey technique, you ...
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4answers
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Real life examples comparable to number of electrons in $1\rm C$

In order to teach 7th-grade students of the enormity of the number of electrons in 1 coulomb of charge $$1\ {\rm C} =6.25 \times 10^{18}~ {\rm electrons}$$ I wish to compare this number to a real-...
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1answer
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Why ionization is more probable in hydrogen atom than excitation to the $n = 3$ level?

The Wikipedia article about the H$\alpha$ spectral line states "it takes nearly as much energy to excite the hydrogen atom's electron from $n = 1$ to $n = 3$ (12.1 eV, via the Rydberg formula) ...
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1answer
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Is an electron an ideal magnetic dipole?

Spin (for example of an electron) is described as an intrinsic form of angular moment, and we often say the electron has therefore magnetic moment, due to this angular moment. Well, I suppose when we ...
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1answer
17 views

Velocity changes at human level and scaling it to atomic level

I am doing an experiment where I need to know the final velocity of the blue ball after the collision. With this knowledge, I can scale this experiment down to the atomic level and have a general ...
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0answers
21 views

Population of sublevels after Zeeman effect appearance

I have following question. We have a single atom and an ability to excite its electron from ground state, the system is closed. Assume, at instant time, I populate whatever level $ ^ NP_1 $ which has ...
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15 views

Distribution of relative number of fission fragments versus mass number for uranium

For a fission of U-235 the fission fragments have a plot roughly shown below: Is there any basic logic( undergraduate level ) with which we can anticipate this curve? Imho the fission yield curve ...
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1answer
35 views

Hooke's law and atomic scale

Hooke's law is derived in this answer by Taylor expanding an energy potential with arbitrary functional form. This is dependent on the displacements involved being "small". By considering ...
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1answer
51 views

What happens when an object has the same de Broglie wavelength as the size of an object?

This is confusing me so much, we learned in class that to study the structure of nucleons, a lot of energy is required and this is to give a smaller de Broglie wavelength which is for some reason a ...
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1answer
29 views

Excite hydrogen with lower frequency photon [duplicate]

Suppose we have a photons with energies less that the one to excite the hydrogen atom. If the hydrogen atom is scattered by these photon it gains energy. Can we excite the hydrogen atom by this ...
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4answers
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Can two atoms collide inelastically?

Suppose I have an atom A (of mass $m$) moving randomly with some velocity $v$ in free space. Now suppose there is one more similar atom B but moving with a different velocity (smaller than $v$) on the ...
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1answer
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Electric potential between electron and proton is given as a function of $r$, how to find the variation of $r_n$ wrt $n$ [closed]

The electric potential between a proton and an electron is given by $V=V_0\log _e\left( \frac{r}{{{r}_{0}}} \right)$, where $r_0$ is a constant. Assuming Bohr’s model to be applicable, find variation ...
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1answer
80 views

Magnetism and atoms

I have a little question about magnetic fields. Suppose we have an uniform magnetic field $\vec{B}$ and a metal wire immersed in $\vec{B}$ crossed by a stationary corrent $i$ . I know, for the Second ...
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27 views

What exactly is an Electromagnetic oscillator? What is its relation with photon?

I have come across the statement that "The physicist Lord Rayleigh thought of the electromagnetic field as a collection of oscillators of all possible frequencies." and also "Planck .....
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0answers
50 views

Excitation of $n$ inhomogenous two-level atom with different detunings? Bloch sphere

I am learning about the bloch sphere and how it is used to to in two level systems. I have done some research already but I am slightly confused. Suppose you have an $n$ number of inhomogenous atoms ...
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4answers
95 views

Why can't we make our own fundamental particles? [closed]

Why can't we make our own fundamental particles ?Is it because we haven't figured out what the most rudimentary particle is made up of?
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2answers
31 views

Atomic orbital, spin quantum number

From wikipedia page about Atomic orbital: Each such orbital can be occupied by a maximum of two electrons, each with its own spin quantum number s. I though that all electrons had same spin quantum ...
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0answers
24 views

What is a thermal source and its spectral-thermal modes?

I know what a thermal state is. But I am wondering how we can determine that a source is thermal or not? E.g. is the light coming out from an LED, thermal? On the other hand, what are spectral-thermal ...
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2answers
77 views

Can I apply first law of thermodynamics on atoms?

I am sorry if this question is dumb but can we apply the first law of thermodynamics directly on atoms? I've say an ion and I'm adding an electron to it, can I write anything like $$d U=d Q-d W$$ to ...
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Ionisation energy of hydrogen: Why are kinetic and potential energy connected by $2 T = -V$ in the derivation? [duplicate]

The following is a translation from the German Wikipedia: The ionisation energy or binding energy B is the sum of potential energy V and kinetic energy T of the electron. $B = V+T$. Since the ...
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3answers
58 views

EM radiation inside atoms

If atom is composed largely of "empty" space what happens INSIDE the atom when immersed in EM radiation? Does the EM wave propagate INSIDE the atom? For example, gas atoms in space, a radio ...
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15 views

Back of the envelope calculation for energy released by fission bomb based on binding energy?

I read that the strong force is twenty frigging pounds between every two tiny protons. So by multiplying this, say, 10kgs by the number of atoms that undergo fission, do we get roughly the energy ...
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1answer
59 views

How much does the radioactive core of a nuclear bomb shrink due to compression by conventional explosives before it goes critical?

I saw a claim online that the conventional explosions used to detonate a nuclear bomb "significantly" compress the radioactive core, but I can't find any numbers indicating by how much the ...
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3answers
82 views

What would the world look like if muons were stable?

Since they are a sort of 'heavy electrons' also 'muonic atoms' could form. These have ben also produced in the laboratory. However, they are unstable. But I was wondering what consequences it would ...
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2answers
29 views

A confusing question on absorption spectrum

Every solution of this question on the internet seems to indicate the answer is option (3). Their reasoning is that, since X is the ground level and absorption of light occurs in the ground level (...
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0answers
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What is the continuum function in $R$-matrix basis?

In the book $R$-Matrix Theory of Atomic Collisions it is defined the $R$-matrix basis \begin{aligned} \psi_{k}^{\Gamma}\left(\mathbf{X}_{N+1}\right)=& \mathcal{A} \sum_{i=1}^{n} \sum_{j=1}^{n_{c}}...
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2answers
63 views

How does relativistic contraction look like at a microscopic level?

Consider a rod with length $L_0$ in its rest frame (call is $\mathcal S'$). Suppose this is the distance between the ends of the rod in the $\hat x$ direction. As well known from special relativity, ...
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0answers
25 views

Why the energy of a state increases with increasing azimuthal quantum number $\ell$?

I am reading Griffiths' introduction to quantum mechanics. But I am confused about the relation between the state energy and azimuthal quantum number $\ell$, which is discussed in Chapter 5.2.2 where ...
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1answer
23 views

Why is Stopping Potential Independent of Frequency of Photoelectron?

All the books and internet articles I have read so far claimed that the stopping potential and the maximum kinetic energy attained by a photoelectron is independent of the intensity with which the ...
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2answers
182 views

How do electrons move from one energy level to another?

EDIT 1: Many people are recommending that the question Do electrons really perform instantaneous quantum leaps? is very similar to mine. However, that question is very specific to quantum leaps. I am ...
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4answers
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Physicists adding 3 decimals to the fine structure constant is a big accomplishment. Why?

Yesterday, a team of physicists from France announced a breakthrough in nailing down a "magic number" by adding three decimals to the the fine-structure constant (news article; technical ...
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1answer
67 views

Conceptual question about the transition dipole moment and its components

I'm looking at the following transition: $1s\to2p$. For this transition, my textbook says: We have to consider three degenerate $m$-components $m=0,\pm1$. We put the quantization axis in the $z$-...
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When can two electrons be excited in an atom?

In the National Institute of Standards and Technology's database, there is a table of the spectral lines produced by each atom in the periodic table https://physics.nist.gov/PhysRefData/Handbook/...
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4answers
1k views

Is the energy of an orbital dependent on temperature?

In the Schrodinger Equation's solution for electron orbital energy levels of the hydrogen atom there is no temperature dependency. $$ E_n = - \frac{m_{\text{e}} \, e^4}{8 \, \epsilon_0^2 \, h^2 \, n^2}...
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3answers
68 views

What are the axes in the structure of an atom?

When learning about the structure of atoms, I learnt that there are orbitals oriented along certain axes. What does it mean to be oriented along the axes? What is the reference? Also, when learning ...
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What are the cross-sections for neutral-impact excitation?

One way for bound electrons in an atom (e.g. neutral helium) to transition to a higher energy level is via electron-impact excitation (i.e. collisions with free electrons). Accordingly, one can ...

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