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 do I remove the negative sign from this derivation?

A homework problem required me to show that the first equation below can be written in the form of the second equation. It was all fairly simple except for the negative sign. I'm not sure how this is ...
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45 views

Cold Solid Matter at the End of a Black Hole's Acceleration Disk?

Is it possible that black holes magnetic field are rapidly cooling matter using a type of magneto caloric effect and cold fusion creating new matter only possible with a black hole's gravity? A type ...
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45 views

Bohr radius question [on hold]

I'm doing a homework problem where it asks to calculate the diameter of a hydrogen atom with $n=600$. I used the equation $r=\frac{n^2a_0}{Z}$ where $a_0=0.529e^{-10}m$. Solving for $r$ yields: ...
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25 views

Calculate the Bohr radius of a muonic atom [on hold]

I want to better understand this problem and how to calculate the Bohr radius. The equation I found in my book is $r_n=\frac{n^2 \hbar^2}{mkZe^2}=\frac{n^2a_0}{Z}$. However, I found a problem online ...
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1answer
22 views

Wavelength for imaging an ultracold atom?

I was reading Stamper-Kurn's article Experimental Methods in Ultracold Atomic Physics (link). In the imaging section (page 13), he mentions: Cold atoms are conventionally probed by optical ...
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36 views

If increasing applying energy to an atom excites electrons, why does electrical conductivity decrease as temperature increases?

Applying energy to an atom makes the electrons jump up to higher energy levels. This is known as excitation. Electrons on higher energy levels are easier to remove from an atom than those on lower ...
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35 views

Magnetic field of one electron

I want to reproduce a calculation of the magnetic field at the atomic nuclei produced by one electron in hydrogen: Maxwell gives us: $\vec \nabla \times \vec B = \mu_0 \vec j$ Doing the surface ...
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4answers
599 views

Why do electrons jump between orbitals? [duplicate]

When an electron is excited to higher energy levels, it will jump back to the same level from which it was excited. Why does it develop "sentiment" with that level?
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22 views

Why is Bohr's explanation called Bohr's model and not Bohr's theory?

I have seen an answer which tells the difference between model (specific) and a theory (general). And it makes sense 'coz Bohr explained it for the hydrogen atom only. But did he not make a set of ...
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1answer
38 views

Potential energy of a spherically symmetric charge density in a spherically symmetric electrostatic potential

I'm interested in calculating the potential energy of a spherically symmetric charge density in a spherically symmetric electrostatic potential. More specific, I'm currently trying to calculate the ...
2
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1answer
41 views

Absorption of photon as particle by an electron

As the photon gets absorbed by the electron and goes to higher energy state, does the photon remains in the electron itself in some form (radiation energy), thereby increasing the mass of electron?
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2answers
25 views

Intensity - wavelength graph for X-ray

This is an intensisity vs. wavelength graph of X-ray emmision. The cut-off wavelength is the minimum wavelength of the X-ray emitted. But doesn't minimum wavelength correspond to maximum energy? ...
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38 views

Is there any well-defined, measurable atomic size?

Is there any well-defined, measurable size at the atomic scale? I was under the impression that the van der Waals radius was a good way of describing the size of an atom, but it turns out to be a ...
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2answers
43 views

Bohr's model and positronium

I was trying to get an order of magnitude estimate for the radii and energies of positronium using the Bohr's model. I did find a few places where they have used the reduced mass to replace the ...
2
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0answers
26 views

How precisely do we know the van der Waals radius of hydrogen?

I've found several sources that say the van der Waals radius of hydrogen is $120 pm$. How precisely do we know this number? What order of magnitude is the error on this measurement?
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0answers
54 views

Estimating temperature with Boltzmann relation with split emission lines

I'm trying to estimate the temperature of a plasma through the use of hydrogen lines, $H_{\alpha}$ and $H_{\beta}$ using the Boltzmann relation: $$ \frac{ n_{2} }{ n_{1} } = \frac{ g_{2} }{ g_{1} ...
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1answer
35 views

Internal energy + energy of electron

Internal energy of a system composed of molecules or atoms is the mean energy of all these particles in the system (energy as kinetic energy, potential energy etc..). But what I am seeing that we are ...
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1answer
95 views

What force keeps electrons in their orbitals and not collapse into the positively charged nucleus? [duplicate]

I know about quantum mechanical model of an atom and how electrons behave like a standing waves and there isn't any lower level energy available for electrons below ground state energy and energy ...
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33 views

Two-Photon Transitions

I'm reading these course notes on two-photon transitions at http://cua.mit.edu/8.421_S06/Chapter9.pdf But I can't understand why it looks like they do not allow for Autler-Townes splitting. In ...
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20 views

Does an electron's energy decrease while performing its motion? [duplicate]

While revolving around the nucleus if the electron's energy decreases then will it hit the nucleus and if it does what will happen?
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2answers
45 views

What is basic difference between photoelectric effect and Compton effect?

What is basic difference between photoelectric effect and Compton effect? In both case a photon hits a loosely bound electron So whats the difference? We get current in photoelectric effect but not in ...
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1answer
48 views

Derivation of the Rutherford scattering formula

I have been trying to look for a derivation of the Rutherford scattering formula from Hyperphysics, but cannot find one. It doesn't show up in the original paper How is this equation derived? ...
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4answers
65 views

What is meant by an excited atom?

I want to know how an atom is when it is excited. If an atom, due to collision of another fast moving atom, becomes fast moving as well, is that also an "excited state"?
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1answer
51 views

Energy of hydrogen atom - Schrodinger equation [closed]

The wavefunction of the electron in the hydrogen atom is $ k* exp(-r/a)$ (k is the normalization constant), but it does not take n into account, whereas the solution of Schrödinger's equation ...
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1answer
31 views

Z coordinate expectation value of the Hydrogen atom

I want to find $z-coordinate$ expectation value $\textbf{<z>}$ of the Hydrogen atom wave function $\psi_{1,0,0} = (\pi a^3_0)^{-1/2}e^{-r/a_0}$ in its ground state. I read in some text that ...
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45 views

Is the Fermi golden rule really accurate for calculating the life time of an atomic level?

In my impression, Fermi golden rule is routinely used in calculating the life time of an excited atomic level. But it is based on the first order perturbation theory, so it is not expected to be ...
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21 views

Can I get Magnesium into gas at room temperature?

This might sit squarely at the intersection of physics, chemistry, and quantum mechanics. I make gas discharge tubes. One color that evades me is green. Apparently Magnesium will do this, but I ...
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13 views

Coupling between angular momenta of particles conserve angular momentum of each particle?

Suppose there are two particles in angular momentum numbers $j_1$ and $j_2$ respectively. Suppose there is some interaction that couple together the particles' angular momenta. As there is no external ...
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1answer
57 views

Is Neutronium possible?

Now I am not talking about neutron stars here. I am talking about a supposed substance with only neutrons in the nucleus. All atoms of this category would have a negative charge and negative charge ...
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1answer
70 views

What do term symbols with a half-integer “$L$” like $^3[3/2]_{1/2}$ mean?

Atomic term symbols are used to notate the angular momentum content of the electronic states of an atom, and are normally written down as $$^{2S+1}L_J$$ where the state has total spin $S$, spin ...
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28 views

Natural linewidth of hyperfine levels?

The D2 line of $^{87}Rb$ is the transition between the $5^2$$P_{3/2}$ and the $5^2$$S_{1/2}$ states. Its linewidth $\Gamma$ is always quoted to be $\sim 6 MHz$. But both states have hyperfine ...
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0answers
50 views

What is the physical meaning of the parameter of a Poisson distribution?

I have done a laboratory session at my university where I had to check that the disintegration of nucleii follows a Poisson distribution. $$P(n)=\frac{\lambda^n}{n!} e^{-\lambda}$$ Where $P(n)$ is ...
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151 views

Is this a correct demonstration for why elements above untriseptium cannot exist?

With the confirmation that elements 113, 115, 117, and 118 are indeed fundamental elements that are now to be named on the periodic table, the next question is: what is the highest atomic number ...
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57 views

Broadband light term in a Hamiltonian

In atomic systems, for a two-level system, the Hamiltonian can be written in the form: $$H=\left( \begin{array}{cc} E_1 & C_{12} \\ C_{21} & E_2 \\ \end{array} \right)$$ where $E_1$ and ...
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1answer
114 views

Hydrogen atom in superposition of energy eigenstates

Suppose a single hydrogen atom is in a superposition of energy eigenstates: $$ \psi = \frac{1}{\sqrt{2}}\psi_{100} + \frac{1}{\sqrt{2}}\psi_{200} \,.$$ Then energy will be $E = ...
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1answer
36 views

Minimum Power Required to Maintain a Population Inversion

According to many sources, the minimum power required to maintain a population N in the upper level of a two level laser system is $$P_{min}=fA_{21}Nh\nu$$ where $f$ accounts for the lack of 100% ...
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15 views

Stark broadening and Voigt fitting

I have LIBS spectral data acquired with a CT spectrometer of resolution 0.4nm. I fitted the Voigt profile into the spectral peak at $\lambda_0$. The lorentz $\Delta \lambda_L$ and the gaussian ...
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1answer
37 views

What is the conditions to excite an atom by collision?

I know that an atom can become excited in one of two ways: by absorbing some energy from a source of electromagnetic radiation or by colliding with some other particle—another atom, for example, but ...
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1answer
35 views

What is an object made of? [duplicate]

If object made of atoms and atoms are invisible then when we look at an object or touch an object what we see or feel?
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1answer
55 views

By what mechanism is a photon emitted or absorbed in atomic electron state transitions?

I understand atomic emission and absorption spectra well - photons of a specific energy can be emitted or absorbed by atoms, if that energy corresponds perfectly to the energy difference between two ...
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3answers
582 views

How can light emit three kinds of spectra?

In case of black-body radiation, radiation gives continuous spectra. Molecular spectra is an example of band spectra. Similarly, there's also the atomic spectra. Why are the spectra of light not same ...
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1answer
130 views

Fusion, Magnets and Quantum Generators [closed]

I cannot even play like I'm even at this level, but this is the fusion reactor in Germany called the Wendelstein 7-X stellarator. These doughnut-shaped magnets (often seen on Physic Exchange) are ...
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3answers
57 views

Are atoms elementary? [closed]

I'm reading wikipedia about Real neutral particle. I know, there are many different particles discovered in the background of atom, which was ( Neutrons + Protons + Electrons ) before. For example, ...
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1answer
44 views

Which electron is first ionized $n=2,\ell=1, m=?$ [closed]

Eletrons in atoms are described by n,l, m, s quantum numbers? For noble gas 1s2 2s2 2p6 which is the first electron that will be ionized n=2, l=1, m=?, s = ?
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32 views

Multi-photon excitation probability for a two-level system

If a two-level system with a lifetime $\tau$ is excited with a pulse of duration $t_{pulse}$, what is the probability of exciting more than one photon? For simplicity we can take it to be a $\alpha ...
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0answers
25 views

Oscillator Strength vs. Dipole Moment

I'm reading "Bose-Einstein Condensation in Dilute Gases" and, in the background chapter (on page 51), the authors introduce the idea of the oscillator strength for a particular transition. The ...
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1answer
29 views

Free space problem in matter [duplicate]

We know that atom is ninety nine percent empty and all matter is made up of matter then why matter is mostly empty ?
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28 views

Is the electron of carbon identical to that of hydrogen? How to prove it? [duplicate]

I am still confused with whether, for example, the electron of carbon is exactly identical to that of hydrogen. How can the scientist confirm this?
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34 views

What is $r$ in angular momentum quantization rule?

We know $$mvr= nh/2π $$ What is $r$ here if I consider positronium system. I suppose it should be the radius of the orbit in which both are moving. But when I take the above equation and electrostatic ...
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1answer
273 views

Are orbitals observable physical quantities in a many-electron setting?

Orbitals, both in their atomic and molecular incarnations, are immensely useful tools for analysing and understanding the electronic structure of atoms and molecules, and they provide the basis for a ...