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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, ...

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Finding Stable Most Stable configuration for Thomson Atom of 2 Electrons

I have been having trouble solving a problem related to Thomson's model of the atom. Basically, if I assume the atom to be a sphere (of radius R) of uniformly distributed positive charge, and if I am ...
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Molecular spectra

In the case of molecular spectra, we say electron transition from one rotational(or vibrational) energy state of 'molecule' to another state. So, my question is where does this transition takes place ...
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2D diffraction pattern: Benzene (hexagon)

I am currently looking at 2D diffraction pattern. For starters I read: https://www.doitpoms.ac.uk/tlplib/diffraction/diffraction3.php When I have N=6 atomic scatteres in 1D just in a line, it will ...
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Electron movement in 3d Bohr model

During a thought experiment, I observed that I was not able to figure the Bohr model in 3d. In every picture I saw up to today, the electrons orbit the nucleus on a fixed circle-like path. But while ...
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How can an ion ever capture an electron if an electron requires a precise momentum to match a subsequent orbital?

Suppose an electron approaches a proton with greater energy than the hydrogen ground state. Will the electron scatter? If so, how could an electron ever be captured given it would require exactly the ...
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How in Cesium 137 spectroscopy Barium X-rays being detected?

Iv been looking at gamma ray spectroscopy of late for a project that I am currently researching and going to be doing in the lab, but what I cannot seem to figure is how the barium x-rays are being ...
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41 views

What effect causes energy difference between $2 \:^1 S$ and $2\: ^1 P$ electron state in a helium atom

I'm wondering where the energy difference between the two electron states $2 \:^1 S$ and $2\: ^1 P$ comes from in a helium atom. I thought it is the fine structure, but the fact that $S = 0$ is ...
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Confusion regarding the orbital angular momentum of mesons in an excited state

I came across the statement that Mesons can have a spin of a whole number (e.g. 1 or 2) instead of the regular 0, as a result of the orbital angular momentum they have in their excited states, with ...
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Does an electron's drop from $2s$ to $1s$ produce the exact same type of photon in different atoms and molecules? [closed]

Does an electron's drop from $2s$ to $1s$ produce the exact same type of photon in different atoms and molecules? Also, does a change from a higher principal quantum number to a lower one always ...
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Is relativistic quantum mechanics really a dead subject? [closed]

While reading about fine structure corrections to atomic physics I realized that Relativistic Quantum Mechanics cannot be abandoned as a dead subject. The fine structure corrections come from Dirac ...
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How do electrons gain energy in the Cathode Tube?

The following is an image from Wikipedia: Aston dark space: Electrons leave the cathode with an energy of about 1 eV, which is not enough to ionize or excite atoms, leaving a thin dark layer next to ...
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Electric Discharge in Cathode Tube

The below figure is a typical V/I plot of a glow discharge Explanation: A – B During the background ionization stage of the process the electric field applied along the axis of the discharge tube ...
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Electron falling into proton approaches infinite kinetic energy why?

Foreword I believe this question to be different from the usual "Why don't electrons fall into the nucleus" because this A: asks about the details of explanations for why electrons don't fall into ...
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Doesn't the Bohr's atomic model violate Maxwell's theory of electromagnetism? [duplicate]

According to Bohr's atomic model, the electrons do not radiate energy when they revolve in the predefined orbits. But according to Maxwell's theory of electromagnetism, an accelerated charge produces ...
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57 views

Why does the nuclear charge remain the same in Moseley's law?

So Today I was taught about the Moseley's law and its relation with Bohr's formula : $$\frac{hc}{\lambda} = R \left(\frac{(Z-\sigma)^2}{n^2}-\frac{(Z-\sigma)^2}{m^2}\right)$$ My understanding is ...
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Different energy levels of an atom vs. electron shells

I am confused about the following point: When studying graphs such as the one below, which depicts the different energy levels of an atom (Mercury in this case), I always thought that the different ...
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Why is the transition from the $3s$ state to $3p$ state in nitrogen observable in the emission spectrum but not in absorption?

Why can one observe an electronic transition of the $3s$ state to the $3p$ state in the emission spectrum of the nitrogen atom, but not in its absorption spectrum? I know that the selection rules ...
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136 views

Why does an electron not emit energy when it is in a stationary state?

The Bohr's postulate states that an electron does not emit energy when it is in a stationary state. My question is, is it only a postulate or does it have proof? Also on what basis did Bohr come to ...
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What happens when an electron in a coherent superposition interacts with a coherent laser beam?

Suppose we have an electron which may occupy three electronic states states $|1⟩, |2⟩,|3⟩$ with energies $E_{1}, E_{2}, E_{3}$. It happens to be the case that $E_{3} - E_{2} \ggg E_{2} - E_{1}$, so ...
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Atom-field interaction for two level system: decomposition of the dipole moment on $|0\rangle$ and $|1\rangle$

On page 145 of Exploring the quantum, atom cavities and photons by Serge Haroche and Jean-Michel Raimond, we have a two level system (an atom) interacting with a classical field. From what I ...
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If an apple is magnified to the size of the earth, then the atoms in the apple are approximately the size of the original apple

Quoting from the Feynman Lectures on Physics - Vol I: The atoms are 1 or $2 \times 10^{−8}\ \rm cm$ in radius. Now $10^{−8}\ \rm cm$ is called an angstrom (just as another name), so we say they are ...
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What would measuring the position of an electron in an electronic superposition look like?

In view of the Copenhagen interpretation, the state: $$\Psi = \frac{1}{\sqrt{2}}|0⟩ + \frac{1}{\sqrt{2}}|1⟩$$ is interpreted as "when the system is measured, you have a 50% chance of finding the ...
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J J Thomson experiment for electron discovery [closed]

Thomson noted that his values for the charge to mass ratio for the electron were about 2000 times larger than those for the lightest known ion, that of hydrogen. Could he distinguish from his data ...
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Electric field energy contribution of proton to its inertia

Quoting from the book Introduction to elementary particles by Griffiths. Here two refers to proton and neutron. Heisenberg’ proposed that we regard them as two “states” of a single particle, the ...
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Formula for number of atomic orbitals for a given $n$

In my studies, it is stated that an atomic orbital is usually described in terms of three quantum numbers: $n$, the principal quantum number, $l$, the orbital quantum number and $m$, the magnetic ...
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76 views

Force between nucleus and electron [duplicate]

Let's say we have a hydrogen atom in electric field. If the field is strong enough, electron will be separated from nucleus. How to determine the value of $E$ at which it happens? To my understanding,...
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2answers
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Why are there no transitions between orthohelium and parahelium?

I know the transition rule $\Delta S = 0$. But where does that rule come from? Is it just very unlikely that an absorbed/emitted $\gamma$ will carry the energy necessary for a spin flip? Or is there ...
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49 views

Does Thompson's atom model have a solid positive material, or a positive “cloud”?

I understand that the explanation of why Rutherford's experiments disproved Thompson's model is that they expected all the alpha particles to go through the space between atoms with minimum deflection....
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Selection Rules for RF and microwave transition

Consider we want coupling between two hyperfine levels both in the ground state of 87Rb atom. Is the dipole transition rules still valid if we use RF or microwave?
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Why atom has the straight discrete energy levels? [duplicate]

Interaction between a nucleus and electrons is in gravity(not considering) and electrostatics. Due to electrostatics nucleus attracts electrons. The force that describes this process is $$F=k\dfrac{...
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Finding quantum numbers by given atomic orbital

Given is an image of atomic orbitals for $n=2$ ($n$ being the principal quantum number): The task is to assign the other quantum numbers $l$ and $m$ for each individual one. How do I do that? I ...
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Is a boron atom isotropic in the absence of a field? If so, how can one write its electronic state?

Is a boron atom isotropic in the absence of a field? If so, how can one write its electronic state? An atom in the absence of any field should obey a spherical symmetry (unless there's spontaneous ...
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Why is the energy of $2s_{1/2}$ greater than the energy of $2p_{1/2}$ after the Lamb shift is taken into account?

The Wikepedia article here defines Lamb shift as a difference in energy between two energy levels $2s_{1/2}$ and $2p_{1/2}$ (in term symbol notation) of the hydrogen atom which was not predicted by ...
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How does the pulse phase influence NMR/NQR excitation?

I'm studying nuclear quadrupole resonance (similar to NMR) and I am trying to understand the notation of the excitation sequences used in NQR spectroscopy. For example, the SLSE sequence is generally ...
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1answer
53 views

Annihilation of matter and antimatter of different kind

What happens when antimatter of an atom interacts with matter of another atom? For example, if I collide antihydrogen and helium. I always heard that collision or interaction of antimatter and matter ...
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Atomic bonding forces -

I was watching IBM's short film called How to move an atom and it got me thinking the following: What element would one use as a surface in order to get the lowest ...
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87 views

Is it possible to use force to reduce the empty space in an atom?

Atoms are mostly empty space (at least from what I've heard) so is it technically possible to shrink the space between the electrons and the nucleus of an atom?
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Why the free electrons in space can not be excited by photons? [duplicate]

Any electron (in the shell) at any orbit of around of an atom can be stimulated by photon (of course as depending on the energy level of photon). So that, it can change its orbit and come back ...
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What is the difference between charge for specific charge in an ion vs not an ion? [duplicate]

The method for working out the specific charge requires charge to be calculated. To calculate a charge when not an ion, if I'm correct you multiply proton number by charge of proton. How do I change ...
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38 views

Electron gas and the infinite potential well

I want to fully understand the electron gas but I am sometimes confused about its behaviour, due tho its models. So the materials like metals got its ionts periodically arranged in the crystal ...
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1answer
30 views

Determining excitated state of an electron of an $\rm H$ atom

Suppose we have an electron of $\rm{H}$ atom( suppose it is at 4th shell). But it can't remain in the excited state for a long time. So it can jump to 1st ,2nd or the 3rd orbital. What is the factor ...
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Is there something similar to time step increments for simulating a system of multiple particles in quantum mechanics?

In Newtonian Physics it is possible to simulate a system of multiple electrically charged bodies, that all exert an electric force on each other, using time step increments. For instance given the ...
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Physical meaning of quantized energy of electron (or n=1,2,3…) in Bohr's model

To solve objections on Rutherford's model, one of which is energy deficit, Bohr postulated that the energy of the electron is quantized and $n=1,2,3...$ . But what does this postulate mean physically? ...
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Why are there dark lines in an absorption line spectrum from the Sun? [duplicate]

Consider this image and quotations from Basics of Radio Astronomy for the Green Bank Telescope: When a continuous spectrum is viewed through some cool gas, dark spectral lines (called absorption ...
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121 views

Two E-fields and two energy levels create infinite frequencies?

In this paper it says that for a two-level system excited by two fields: $$ V_{ab} = -\mu_{ba} E_1 e^{i \omega_1 t}+ E_3 e^{-i \omega_3 t}$$ "In steady state the off-diagonal density-matrix ...
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About the (retro)causality of an anti-atom

It is commonly said that one can view anti-matter as 'matter going back in time'. I'm trying to figure out how far this analogy goes. For an atom, it is well-known how that atom excites absorbing a ...
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Collapse operators in multi-level atomic systems?

I'm trying to understand the case of multiple ground states and excited states. Due to selection rules, usually we say there should be 3 collapse operators, namely C_+1, C_-1, C_pi, corresponding to ...
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What do the dashed lines represent in this figure from the discussion of the Zeeman effect in Griffiths?

Consider the figure below (figure 6.12 from Griffiths, Introduction to Quantum Mechanics, p 249 in the 1995 edition), which shows the Zeeman effect on the $n=2$ eigenvalues of hydrogen. The figure ...
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Why do electrons abide by Hund's rule?

Is the reason why Hund's rule exists, that when electrons are in different orbitals (such as 2px, 2py, or 2pz), they are most stable (lowest energy)? If the purpose is stability/lowest energy, ...