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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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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47 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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60 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 ...
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29 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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73 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} }e^...
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1answer
75 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
116 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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39 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
90 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
270 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? $$N(\...
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4answers
149 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
69 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 ($H(...
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1answer
78 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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0answers
52 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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25 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 don'...
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25 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
101 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
92 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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49 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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1answer
73 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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185 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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1answer
60 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
185 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 = \frac{1}{2}(13.6\,\...
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1answer
46 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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1answer
38 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
80 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
62 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
251 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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597 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
153 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
62 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
52 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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40 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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48 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
38 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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29 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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35 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
316 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 ...
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2answers
124 views

Laser cooling of atoms: more area or more power?

I want to optimise a Magneto-Optical trap. Laser beams come from the the x, y and z directions (positive and negative) and slow the atoms down. Would it be better to increase the beam spot-size (...
8
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2answers
230 views

What does an orbital mean in atoms with multiple electrons? What do the orbitals of Helium look like?

I am wondering about this. It is a familiar sight, the orbital diagrams for the hydrogen atom, depictions of which are abundant and so are not in need of reproduction here. However, what about the "...
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1answer
37 views

What is the reason behind the very high value of nuclear density? [closed]

I know how to arrive at the formula but I want to know it's such a huge number almost 2 X 1017 kg m-3, which is a huge number, all the more surprising to me is that it's a constant! Each and every ...
3
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1answer
107 views

Does the spin of an electron change when transferred from one atom to another?

Some atoms form bonds when they are given energy to create an excited state.From what I have learnt, every electron is assigned a specific spin quantum number. What I am curious to know,is that, is ...
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3answers
407 views

Can an electron gain energy by another electron?

Is it possible for an electron to gain energy from another electron which is jumping from higher energy level to lower energy level, and shifts to higher energy level?
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1answer
62 views

Does the proton wobble due to the electron's orbit in a Hydrogen atom?

In a hydrogen atom the nucleus only has one proton and no neutrons so the electron to nucleus radio is higher for hydrogen than that for any other atom. Does the orbiting electron induce a wobble on ...
4
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1answer
131 views

Are atoms unstable in 4+1 dimensions when quantum mechanics is taken into account?

I understand that in 3+1 dimensions according to classical physics atoms should be unstable however atoms are stable in 3+1 dimensions because the behavior of atoms is governed by quantum physics ...
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57 views

Can one measure experimentally the average distance between the two electrons in the excited state of helium in the singlet versus triplet states?

$\frac{1}{\lvert\ \vec(r_{1})-\vec(r_{2})\rvert}$ is a hermitian operator so I am supposing there could potentially be an observable with this which might be experimentally measured. We can measure ...
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8 views

Discrepancy of capture from 2p+1 state to 2p(+-1)

In the (nlm) characterization of hydrogenic orbitals. Consider the collisions H+ + H(2p+1) ---> H(2p-1) + H+ H+ + H(2p+1) ---> H(2p+1) + H+ where an electron capture has ocurred. Should the ...
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2answers
180 views

Possible inconsistency in Bohr atom model [closed]

It is well known that Bohr model is not totally right. But I recently discovered a very curious inconsistency (if I am right) which I haven't seen explained anywhere. The first postulate of Bohr ...
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1answer
51 views

The point of charge neutrality in the Hydrogen Atom

If we treat the Hydrogen Atom like the Bohr model then we have a proton in the center with an electron orbiting at some radius (the Bohr radius). In this picture you can imagine the electric field ...