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, ...

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How long does an electron stay on a given orbital?

Was wondering what the average time is for an electron on any given orbital, or how often they change energy levels. Thanks in advance.
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54 views

Why does most galaxies resemble a 2 dimensional plane? [duplicate]

Older galaxies mostly tend the revolve forming a disk. Why are the stars not revolving around the center of the galaxy like a sphere instead similar to electron in an atom?
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1answer
35 views

How to find the magnetic field due to a revolving electron of hydrogen atom in first orbit

So, I was thinking about the Bohr model of atom and I started to wonder how we could find the magnetic field due to a revolving electron (produced at the location of proton) of hydrogen atom in first ...
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2answers
31 views

What is the energy transformation in the fission reaction?

According to one of my physics textbooks, when U-235 absorbs a neutron it becomes unstable and soon fissions into two separate atoms. The forces driving these two atoms apart are electrostatic forces ...
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2answers
75 views

The counter-intuitive time scales in atomic physics and nuclear physics

Compare atomic physics and nuclear physics. The interaction in the latter is much stronger than that in the former. However, the typical spontaneous emission time scale in atomic physics is on the ...
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44 views

Derivation of Critical Mass of U-235

I am having trouble following an explanation of the critical mass of U-235 from my book (for high school physics). First off, every chain reaction of U-235 releases on average $\nu = 2.42$ neutrons. ...
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36 views

What is so special about atomic nodes and why do they exist? [duplicate]

Using Schrodinger’s wave equation we see that there are certain nodes, i.e radial nodes where the probability of finding the electron is minimum. These nodes are sometimes very close to the nucleus ...
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2answers
58 views

Energy released due to electrons transition

I came across this question in one of my physics books: Choose the correct answer: According to Bohr's model of the Hydrogen atom, the transition of an electron from n=2 to n=1 leads to release of ...
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0answers
62 views

Stark effect in Polonium and Plutonium

I found the following question given as an exercise in one lecture notes: What are differences between Stark effect in Polonium and Plutonium ? What are differences between Stark effect in light ...
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5 views

Why are these H cross sections given as a function of energy per amu?

The Atomic and Plasma-Material Interaction Data for Fusion Vol. 4 (1993) by the IAEA lists empirical fits for ionization and excitation of hydrogen by collisions with $\mathrm{H}^{+}$. The fits are ...
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1answer
26 views

selection rules and singlet state

In an introduction I read the following sentences: "In excited singlet states, the electron in the excited orbital is paired (by opposite spin) to the second electron in the ground-state orbital. ...
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2answers
71 views

An unknow atom has the shown energy levels

In an excersice i found, a supposed atom called fictitious (Fi) has the following energy levels: Then i´m asked: A) The energies of the emitted photons after a gas of Fi is bombarded with ...
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1answer
79 views

Is this incredible microscope technology real? [closed]

I recall reading about the relatively old invention of a microscope-like device; apparently able to zoom much further (and with greater clarity) than more "advanced" modern technology. I don't recall ...
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0answers
11 views

What is exactly the difference between an active and passive frequency standard?

In the case of passive atomic frequency standard, we take an atomic reference which has a resonant frequency response centered at certain particular frequency. Then we take a local oscillator and tune ...
0
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1answer
25 views

Can a magnetic field speed molecules up?

I heard somewhere that If you add a magnetic field to atoms in a closed space you would speed them up. Similarly to heating them up. Is this true is so what the atom consists of for this to work?
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2answers
61 views

Is there a way to make atom move faster without heating them?

The more heat you add the faster the atom will move. This is something that is common knowledge. My question is it possible to make the atoms in let's say a gas move faster without adding heat of a ...
0
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1answer
49 views

Can/will a proton escape the nucleus when a force is applied? [closed]

Protons are contained within the nucleus of an atom. Protons carry a positive charge. With an electric field, we can exert a force on the proton. Is it possible for the proton to escape the nucleus? ...
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1answer
32 views

Does the one-electron cyclotron confirm the classical model?

Reading this short article one gets the impression that, after all, the classical description of the atom is not superseded: In the past, researchers have successfully used several different ...
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0answers
39 views

First order time-independent perturbation theory: How to practically calculate the perturbed wave-function

This is one of the problems that draws the line between academically learning something, and having to use it. While I learned the formulas relevant to this, I just want to make sure I'm using them ...
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2answers
41 views

Where is the periodic nature in the Cs atomic clock? [closed]

In case of pendulum clock,lets say one swing ticks one second..but what is the analogy in case of CAESIUM atomic clock? Is 9,192,631,770 ticks is equivalent to one tick in pendulum clock? And how we ...
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0answers
26 views

How to count such a huge number of oscillation in atomic clock? [duplicate]

A second is defined as time taken for 9,192,631,770 oscillations of caesium hyperfine levels. But it's not exactly that the electron moves up and down between these two levels. So it must be related ...
4
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4answers
153 views

How do light waves get their size?

An atom or (small) molecule has the size of about 100pm. Elektromagnetic waves range from about 0.1nm up to 1 km. The most common way waves (like light) are caused by 'jumping' electrons to another ...
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1answer
38 views

Drive term for a Jaynes-Cummings like hamiltonian

When reading articles on CQED or atomic physics, I often encounter the Jaynes-Cummings Hamiltonian, which in the simplistic form I will write down as: $$H = \hbar \omega_c a^\dagger a + \hbar \frac{\...
3
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3answers
107 views

Why does a “typical” hydrogen atom have no neutron?

There are quite a few sources (mostly high-school physics textbooks) that I've read which don't give the disclaimer that the hydrogen atom they are using in a diagram is an isotope (as in having ...
6
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2answers
69 views

Is there any atom which is dia-electric?

Take an atom. Suppose we impose some magnetic field on it. For some atoms, the energy increases---this is a phenomenon of diamagnetism. The question is, how about an electric field? Can the energy ...
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2answers
55 views

Atom Particles Relationships

I am an agriculture student, and we study tons of chemistry, and despite I took the exams I still have a good doubt on atoms. Through my studies I would say electrons are very tiny containers of ...
3
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1answer
31 views

Reaching equilibrium in a blackbody and light-matter interaction

Suppose we have a metallic cavity maintained at a fixed temperature. Suppose we start with any distribution of radiation that is not in equilibrium with the container. Gradually, when the equilibrium ...
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10 views

How long is the surface migration length of adatoms deposited by thermal evaporation in vacuum?

The deposition of metals through thermal evaporation involves the process of adatoms migrating on the substrate before its kinetic energy decreases to a certain point or before encountering a cluster. ...
30
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3answers
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Is there any truth to interpreting definition of a second as corresponding to oscillations?

As far as I understand the definition of a second, the Cs-133 atom has two hyperfine ground states (which I don't really understand what they are but it's not really important), with a specific energy ...
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4answers
1k views

Why does an electron shell further away from nucleus has higher energy level?

Using electrical potential energy $V=\frac{1}{4\pi \varepsilon_0} \frac{Q_1 Q_2}{r}$ , a particle further away from nucleus has lower magnitude of energy. Using Coulomb's law, a particle further away ...
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0answers
46 views

What is the cause of discrete or quantized energy levels in an atom? [duplicate]

I understand how it is that electrons move from one energy state to another, however I've not been able to find anywhere that describes why an atom has any particular states. Why should an atom of ...
2
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1answer
85 views

Why do electrons not fully fill up all the orbitals sequentially?

Why do electrons not fully fill up all the orbitals sequentially? By this I mean: why don't the electrons fully take up the previous orbit first and then move onto the next orbit? Take calcium for ...
3
votes
1answer
42 views

Spread of the energy levels and sharp energy eigenvalues of the Schrodinger equation of the H-atom

Solving the Schroedinger equation for the H-atom (or any other system, say a particle in a box, or harmonic oscillator or anything), we obtain the energy eigenvalues are sharp with no spread. However, ...
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1answer
31 views

Why is the interaction energy of the electrons in an atom positive?

Consider a simple Hamiltonian for the Helium atom (where $e'^2 = e^2/4\pi \epsilon_0)$: $H=\frac{P_1^2}{2\mu}+\frac{P_2^2}{2\mu}-\frac{Ze'^2}{R_1}-\frac{Ze'^2}{R_2}+\frac{e'^2}{|\vec{R}_1-\vec{R}_2|}$...
1
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1answer
34 views

Energy of photon after emission

Exercise: A hydrogen atom is at its first excited state. When it de-excites it emits a photon. What is the energy of the photon and the kinetic energy of the atom? Question: Is it correct to ...
0
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2answers
125 views

Compton Effect Explanation

Can someone brief me about Compton effect and why does this happen? I searched everywhere read a CERN article too but couldn't understand it.
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2answers
82 views

The calculation of the entropy of a single atom

I used to think that the entropy of a single atom could not be calculated, for in my mind only the entropy of a system containing many atoms could be calculated. But my professor told me the entropy ...
0
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1answer
39 views

Electron velocity in hydrogen

I was speculating over the feasibility of myon catalysed fusion. Somehow I drifted away from that a little, and I was wondering if one can find a quantum-mechanical expression for the velocity of an ...
0
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2answers
73 views

How does electron makes transition from one state to another?

i am not asking why it makes. i am curious about how it makes the transition. Does it go from one state to another via straight line or it makes smaller and smaller orbits till it reaches the next ...
0
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0answers
23 views

Higher $L$ lower energy?

For multi-electron atoms, what is the physical reason behind the fact that a higher total orbital angular momentum, $L$ gives a smaller total energy, $E$?
3
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1answer
66 views

Relativistic correction to Hydrogen atom - Perturbation theory

Given the relativistic correction $$ H_1' = - \frac{p^4}{8m^3 c^2} $$ to the Hamiltonian (i.e. a perturbation), what does it mean when $[H_1', \mathbf{L}] = 0$? The book I'm reading says this implies ...
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2answers
107 views

Density Matrix representation of excited atoms

I'd like to get an answer to this question from someone who knows his density matrix theory. I want to compare two different systems and ask how their density matrix representation looks. First look ...
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0answers
21 views

Clarification: non-relativistic fine structure of a one-electron atom

The fine structure energy shift (in the non-relativistic limit) for a single-electron atom due to spin-orbit coupling is given by $$\Delta E_l\propto\frac{j(j+1)-l(l+1)-s(s+1)}{2l(l+\frac{1}{2})(l+1)}$...
1
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1answer
22 views

The energy of de-excitation

I am 10th class student and what i dont get is when electron dexcites it produces energy but what is main phenomenon which produces energy is it the motion of electron or something like disturbing ...
0
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1answer
44 views

What determines the color of photon that is emitted from an exited atom?

I understand the principle of how light is emitted from an atom. What I don't know is why neon atom is red and copper is green when exited? Is is the distance between the electron to protons or the ...
1
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2answers
59 views

Can AMO physics be applicable for space travel? [closed]

I know it sounds very stupid question. I am a Ph.D student currently working on the AMO physics (Quantum Optics). I recently saw articles about the Spacex, and I thought it is really amazing, and ...
3
votes
1answer
59 views

Why do some elements burn different colors? [duplicate]

I have a torch lighter and it makes a green color when the flame passes over the metal in the center. What on the molecular level would a flame change color although there is no difference in ...
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30 views

Which Hydrogen Emission Lines Appear First?

When a blackbody is heated, it radiates photons. At low temperatures, there isn't much radiation at high-energy end of the spectrum but as the temperature raises, high-energy radiation becomes ...