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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64 views

Will atoms evaporate given enough time?

Thought experiment: someday in the distant future, space will be expanding faster than the speed of light. Imagine that trillions of years in the future, you have a single hydrogen atom. Will that ...
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Why is $m_{\ell}$ called the magnetic quantum number? What is its association with magnets?

I am going over my quantum lecture notes and I can't seem to link the quantum number $m_{\ell}$ with any magnetic property. It just seems to specify the shape of an orbital with a particular principal ...
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Random matrix theory and heavy nuclei

The question is a simple one: Can the same methods that are used for heavy nuclei (by treating the Hamiltonian as a random matrix) be applied to light nuclei, say hydrogen? I realize this is akin to ...
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Transitions within magnetic sub levels: evaporative cooling to Bose Einstein Condensation

Consider a Ioffe-Pritchard trap geometry. Evaporative cooling works by decreasing the trap depth to remove atoms which are more energetic than average; this leads to cooling. This is done by using ...
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1answer
32 views

Relation between Boltzmann's constant $k$ and Avogadro's number?

In an online lecture series on statistical mechanics, Leonard Susskind made a passing comment about how Boltzmann's constant is related to Avogadro number, hence why they are the same order of ...
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Question on Kleinman-Bylander pseudopotentials

When Kleinman-Bylander pseudopotentials are used the Hamiltonian operator is given by $$\hat{H} = -\frac{1}{2}\nabla^2+V_{\textrm{local}}+\delta \hat{V}_{\textrm{NL}}$$ where $$\hat{V}_{\textrm{NL}} = ...
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50 views

Griffiths Quantum Mechanics - How can magnetic quantum number $m$ possibly be negative?

I apologize if this is already somewhere on this site, I searched with relevant keywords but could find nothing. This is from David Griffiths' Introduction to QM. In section 4.1.2 (Angular Equation),...
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How to find to which hydrogen spectrum does electron belong [closed]

Suppose electron jumps from 4th excited state to first. To which series these lines corresponds. ( Lyman , balmer , paschen , brackett , pfund)
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130 views

Is it a typo in David Tong's derivation of spin-orbit interaction?

A few lines below equation 7.8 D. Tong writes The final fact is the Lorentz transformation of the electric field: as electron moving with velocity $\vec{v}$ in an electric field E will experience a ...
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1answer
21 views

Labeling the eigenstates of the many electron Hamiltonian

I'm taking a course on atomic and molecular physics and there is a chapter about finding suitable quantum numbers that label the eigenstates of a given Hamiltonian. The lecture notes say that it ...
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Why is the energy eigenstate of hydrogen atoms $\lvert n\ell ms \rangle$?

When solving the Hydrogen Atom using the Schrödinger's equation, we find the wave function represented in the position bases, and it turns out that the wave function has parameters $n$, $\ell$, $m$, ...
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Why can we only trap certain atoms?

This is a bit open ended, (and probably poorly asked,) but I've noticed that most experimental trapping only works for alkali metals. I know with my limited understanding of how a MOT works, that ...
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Electrons can't orbit at any old radius [closed]

Electrons can't orbit at any old radius from the atom's nucleus, but are rather restricted to only specific orbits at a fixed set of distances. This is called orbital quantization. Why this ...
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Trajectory of electrons (treated classically) in the C-frame

This is a classical treatment of two electrons moving in vacuum. In a frame of reference attached to either electron, I found by solving the 2-body problem, that the other electron would move in a ...
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1answer
77 views

Hydrogen atom from the perspective of the old quantum theory

I am trying to understand the old quantum theory's description of the Hydrogen atom. So far, I have read a physics stack exchange post about Sommerfeld's approach to quantization (Deriving the Old ...
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60 views

Morse interatomic potential

I am working with Morse interatomic potential, I searched through the Internet but I could not find any Morse parameters for Zirconium element. Is there any table, handbook or something like these ...
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34 views

How to prove that atoms exist? More precisely - how come electrons and protons do not fall into each other? [duplicate]

Basically the question that I'm asking. Sure - There are few interactions that take the expected effect - electromagnetic, gravitational, strong and weak interactions. But how can we prove it, exactly?...
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24 views

Why does not a free electron fall into the nucleus during elastic scattering?

When a free electron finds a hole in the medium, they can re-combine and annihilate each other. So far so good. A free electron can also scatter from positive atomic center (say it elastic scattering ...
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48 views

Conservation of Angular Momentum of an Electron

In applying conservation of angular momentum for an electron we use the relation $mvr=\frac {nh}{2 \pi}$ however the angular momentum has terms of velocity and distance from the line of action. ...
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1answer
39 views

Symmetry on Bohr's Hydrogen Atom

I was studying the applications of the Schröedinger wave function in the Bohr's atom. For what I understood, the $\psi$ should only depend on r and not on $\theta$ and $\phi$. Does that mean that $\...
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2answers
82 views

Is it possible to create an atom, proton, neutron and electron?

I know that it is not possible, however, this thoughs keeps me awake and make me thinks a lot. If it was possible how will we create it the atom, proton, electron and the neutron??
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1answer
32 views

How is the concept of binding energy linked to ionization energy?

I understand that the reason when you plot ionization energy against atomic number, you get peaks at the noble gases, is because they have full valence shells. When I was trying to think this through,...
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1answer
47 views

Feynman-Hellman theorem problem in Griffiths - somewhat inaccurate?

Problem 6.33 in Griffiths (typing out only the relevant parts) is stated as follows: The Feynman-Hellman theorem can be used to determine the expectation values of $1/r$ and $1/r^2$ for hydrogen. ...
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1answer
22 views

Why fluorescence lifetime goes down while dopant concentrations goes up?

I noticed, that is laser crystals the low levels of doping are used and that if higher levels did, the lifetime of excited level will be shorter. Why? The atoms of dopant are the same. Why do they ...
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1answer
38 views

How does a one-sided glass work on atomic level? [duplicate]

What does the description of the phenomenon at atomic level look like? I assume that atoms absorb and emit a wave with a changed amplitude. What is responsible for dividing the amplitude level and ...
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3answers
773 views

Conservation of momentum in photon-atom collision

Is this explanation correct: When a photon with the appropriate energy hits an atom, the electron will make a transition from the ground state to a excited state. This will make the potential energy ...
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1answer
38 views

Selection rules for hydrogen atom transitions

I'm reading the book Atomic Physics by Christopher J. Foot and I'm stuck at section 2.2.1 (selection rules). To arrive at the selection rules for $\pi$-transition, the integral of the angular part of ...
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Not sure about Bohr's decision to take $f(\tau)=c\tau$ as determining the atom's energy states in his 1913 paper

From his 1913 paper, the assumption that the electron's angular momentum in atomic orbits must be a multiple of $\hbar$ is equivalent to saying the energy at each stationary state is $W={\tau h\omega}/...
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92 views

Probability of emitting a photon proportional to population in final state: problem with normalization?

In section 4-4 the Feynman Lectures reads: The probability that an atom will emit a photon into a particular final state is increased by the factor $(n+1)$ if there are already $n$ photons in that ...
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1answer
22 views

Analogy of a hydrogen atom in an $n$-type semiconductor

My professor told me that when an intrinsic semiconductor (ex-Silicon) is doped with a penta-valent atom (ex-Phosphorus) then the extra electron is quite far away from the nucleus of Phosphorus.I ...
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1answer
28 views

Color of radium's glow?

Does the radium salt (or metal for instance) glow only because the emitted alpha particles bombard the nitrogen atoms in the air? Still, how does that lead to a glow anyway? What's the color of the ...
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1answer
82 views

Mathematical formalism to show that an atom casts a small shadow in the photon field that illuminate it

This questions regards the relationship between photon absorption and the spatial mode of light. In the question I have some physical intuition which I think I understand and which is born out by ...
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6answers
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Why did the Bohr Model Successfully calculate some of the energy levels in hydrogen?

The Bohr model is incomplete and has drawbacks. But one thing is a mystery to me. Why did it so successfully calculate the Rydberg series with quite good number of correct digits? Having such a good ...
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1answer
50 views

Expansion of the Bohr-Sommerfeld Model to any atomic/molecular system

I know that the Bohr model of the atom was modified by Sommerfeld to include elliptical orbits, and that the resulting Bohr-Sommerfeld theory has long been put aside in favor of quantum mechanics. ...
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3answers
104 views

Energy levels of hydrogen as $n$ goes to infinity

As you increase the energy level of a hydrogen atom $n \rightarrow \infty$ I have learned that the energy of that energy level changes according to $$ E_n =- \frac{13.6 {\rm eV}}{n^2},$$ and that ...
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0answers
48 views

Trying to find $E_n=-E_1/n^2$

I'm reviewing some questions in an old math methods book after a long gap in math and physics for practice, and I think I'm missing something with this question since I always end up with an extra $\...
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2answers
960 views

Why don't atoms emit more than one photon during an energy level transition?

If you look at the emission spectrum of an atom, there are sharp lines corresponding to the different energy level transitions. That's because the single photon emitted during each transition carries ...
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1answer
40 views

Why are $p$ orbitals independent from this symmetry rule?

I am very new to quantum mechanics and I have a question about $p$ orbitals. I am studying Beiser's Modern Physics and according to that in the Bohr Model the wave the probability density of ...
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0answers
26 views

Ground state term symbol, why is $L = |M_L|$, if $L$ must be a maximum?

I'm trying to understand how to predict ground state term symbol of atoms. After finding the biggest S, why the biggest $L$ will be $L = |M_L|$, where $M_L = \sum m_l$? I know this rule works to ...
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2answers
91 views

Should the ground state electron density of an atom go to zero at the origin?

I have heard from my professor that the particle density of electrons (in the ground state) of an atom should vanish near the nucleus. Hydrogen is an obvious counter-example. So I am trying to work ...
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0answers
77 views

Why does lithium have a total electronic spin of 1/2?

The book I'm reading analyses atoms by only looking at the last eletrons, and saying that their wave function must be anti-symmetric. I understand the case of Helium, the spin function must be anti ...
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6 views

Action of alpha rays on zinc sulphide screen [duplicate]

Why does the zinc sulphide screen shows luminescence when α particles strike on it
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1answer
69 views

Formula for the sequence of hydrogen orbital quantum numbers [closed]

My previous question had a poor reception because somebody thought my question was not about physics. Therefore, I repost the question in a less mathematically precise way, such that it is about ...
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1answer
44 views

Why does heating an atom make it emit certain wavelengths?

We're going over quantum basics in chemistry right now and I'm very confused. Electrons can only accept in discreet quanta to move up an energy level, right? And they reflect other forms of light ...
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1answer
41 views

Interpretation of the photon scattering rate?

The photon scattering rate $\Gamma$ describes the rate at which photons scatter off an atom$^1$. In a two-level system, the ansatz for the photon scattering rate often is given by \begin{equation} \...
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1answer
77 views

Does the hydrogen anion have bound excited states?

I'm having some trouble puzzling out the literature regarding the existence of bound excited states in the hydrogen anion, H$^-$. Wikipedia claims that no such states exist, and that the subject is ...
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2answers
78 views

What would happen to an atom with massless electrons? [closed]

I've started to write a Realistic Sci-Fi novel for general fun, but I need to get some info on the Higgs Boson first. See, there is a weapon in the novel, some device that would remove the higgs field ...
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3answers
153 views

Why are double negative ions (Hydrogen) unstable?

This is not a duplicate. I have read these questions: Can hydrogen have 3 electrons? where Buzz says: The double hydrogen anion H−− does not exist as a stable species. (It occurs as a resonance, ...
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3answers
864 views

Electric field due to a hydrogen atom

Electric field due to two opposite charges According to the answers in the previous questions, if you separate the two charges from each other, they will produce a non-zero electric field ...
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65 views

Is Newton's third law held in special relativity regarding Coulomb's force?

Assume a charged mass $(m,+q)$ is revolved around another charged mass $(M,+q)$ at a distance $r$ so that $M>>m$, yet the gravitational effects are negligible. (Such as an electron orbiting a ...