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, ...

learn more… | top users | synonyms (2)

4
votes
1answer
536 views

Two photons transition

if an atom in its ground state is coupled to an electromagnetic field it can absorb a photon if the EM field contains one with the right frequency. These transitions depends on $⟨f|H_i|i⟩$ (from ...
0
votes
0answers
24 views

Polarizable molecule in E-field

If we have a linear molecule with a dipole moment $\mu$ in a static electric field $E$, the potential is given by $V = - \langle \mu,E \rangle$. What is the appropriate equation for the potential if ...
2
votes
2answers
51 views

How does weight add up to press on things?

I think I understand how pressure works with gases. More molecules bouncing around -> more random impacts -> stronger force. But I realized to my embarrassment that I don't understand how solid ...
0
votes
2answers
63 views

Mathematical description of electron configuration

Does there exist a mathematical model for determining the electron configuration of an atom? I mean the theory which would generalize the notion behind the informal elements of the Aufbau principle.
2
votes
1answer
66 views

On use of Hamiltonians for Helium

The Hamiltonian of helium can be expressed as the sum of two hydrogen Hamiltonians and that of the Coulomb interaction of two electrons. $$\hat H = \hat H_1 + \hat H_2 + \hat H_{1,2}.$$ The wave ...
3
votes
1answer
140 views

Electrons skip randomly around their orbits

I read where the electron (as well as a few other particles) skips around in its orbit randomly rather than move around the orbit smoothly. This effect has been repeatedly observed in the laboratory ...
2
votes
1answer
95 views

Why the orbital angular momentum equal zero for electron in s state? does it mean that the electron doesn't orbiting in s

Why is the orbital angular momentum $l$ equal to zero for electrons in the $s$ state? Does it mean that the electrons aren't actually orbiting?
0
votes
1answer
84 views

Thermionic emission, delayed emission and predissociation

In molecular photodissociation, the thermionic emission, delayed emission and predissociation are the same? Otherwise, what is the difference between them? My question is not about the solids, but I ...
0
votes
1answer
93 views

How to distinguish between the spectrum of an atom in motion and the one of a scaled atom?

Galaxies are moving dragged by the space expansion. When atoms are in motion the doppler effect will shift the spectra of the emitted photons. The proton-to-electron mass ratio, $\frac{m_e}{m_p}$ ...
58
votes
2answers
10k views

Why doesn't matter pass right through other matter if atoms are 99.999% empty space?

The ghostly passage of one body through another is obviously out of the question if the continuum assumption were valid, but we know that at the micro, nano, pico levels (and beyond) this is not even ...
0
votes
1answer
178 views

Density matrix and irreducible tensor operators

I'm reading those lecture notes on atomic physics. Yesterday I posed a question on reducible tensors, and today I have a question on their relation to the density matrix. If there's any information ...
0
votes
1answer
88 views

What is absorption of an electromagnetic wave?

Can any one explain the absorption/transmission/reflection of electromagnetic waves in the wave form? It is generally said that the atom absorbs/reflects/transmits photon. But can this phenomena be ...
0
votes
0answers
38 views

Atomic physics - electron density [closed]

Question: Which of the following has zero electron density in the xy plane? (A) $d_{z^2}$ (B) $d_{x^2 - y^2}$ (C) $p_{z}$ (D) $d_{xy}$ Can't the answer either (A) or (C)? The ...
1
vote
2answers
462 views

How is the energy of an electron-shell related to the speed of electrons in that shell?

I am trying to gain an intuitive picture of what is referred to by "electron-shell energy". I have read that outer electron shells have higher energy than inner electron shells, and this seemed to ...
1
vote
1answer
52 views

Coulomb potential in atoms other than hydrogen

The energy of an electron on $H$ atom is given by the formula: $-13.6 \; \text{eV}/n^2$. The constant value is born from $H$ dielectric constant and efective mass of the electron. My question is: ...
0
votes
1answer
34 views

Intermolecular Hydrogen Bonding

I learnt about intermolecular hydrogen bonding today, which occurs between molecules such as ortho-nitro-phenol. What I was told is that in case of intermolecular bonding, the molecules separate from ...
1
vote
1answer
37 views

Atomic Physics - Bohr's model of atom

Well I'm learning about the models that have been proposed for the atom, and the Bohr model came up. My teacher told me that the one of the main postulate of the theory is that when an atom is in ...
2
votes
2answers
242 views

Which cyan colored line is produced in the Thomson e/m apparatus?

Related: Which green spectral line(s) are emitted in a Thomson tube? After reading Lisa Lee’s OP on an electron deflection tube, although she had some misunderstandings on its operation, I still ...
3
votes
0answers
41 views

Does the definition of the SI unit “second” require that possible perturbation of primary frequency standards should be measured?

The definition of the SI unit "second" is stated as The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground ...
1
vote
2answers
72 views

Moseley's Law Conceptual Question

From Young & Freedman, Univ. Phys. p. 1394 about Moseley's law: Suppose one electron is knocked out of the K shell. This process leaves a vacancy, which we’ll call a hole. (One electron ...
2
votes
1answer
21 views

EXAFS (Extended X-Ray Absorption Fine Structure) question?

EXAFS (Extended X-Ray Absorption Fine Structure), core electron is excited to the conduction band. The oscillations in the absorption coefficient persist for 100s of eV after the edge. Taking ...
1
vote
1answer
66 views

Electron distribution around atom when moving

I do not have much experience on this but if an atom has some electrons around nucleus and the atom itself it is moving at some speed does that affect the distribution of electrons around? I am ...
0
votes
0answers
26 views

Two-photon absorption and 3rd order susceptibility

I am referring to introduction of Section 12.5 Multiphoton Absorption and Multiphoton Ionization (Page no. 550 of Nonlinear Optics, Boyd-3rd edition) where it has been said that the two-photon ...
1
vote
1answer
31 views

Atomic physics - lattice energy

Question: Why is ionic lattice energy inversely proportional to the radius of the atom? Most heterogeneous covalent molecules are polar to some extent. The degree of polarity, or the dipole moment, ...
1
vote
1answer
85 views

Hydrogen ionization energy [closed]

Proton and electron have a distance equal to the Bohr radius apart in the hydrogen atom. Knowing this, what's the ionization energy of the atom? So we know $U = -kq^2/a_B$, but this is potential ...
0
votes
1answer
84 views

Is it possible to find the hydrogen atom's radial wavefunctions?

Is there a way to actually find the equation of $R(r)$ without looking at a table with these equations already given? I'm given $n$, $\ell$, and $m$.
0
votes
1answer
73 views

Quantum mechanics scattering theory

When an electron absorbs energy and jumps to the another excited state by absorbing the photon and why it is always said that the electron will come back to $\hbar\omega/2$? Why doesn't the electron ...
1
vote
0answers
49 views

Formation of atoms [closed]

If a Proton goes toward an Electron with a trajectory that forms a circular motion, these particles will form an atom ?
1
vote
1answer
32 views

Atomic physics question - exciting of electrons during bonding

As I have learnt, when bonding takes place in an atom, such as carbon, the electron in its $s$-subshell gets excited and jumps to the open spot in the $p$-subshell. This is why carbon is able to form ...
4
votes
1answer
55 views

Do metals have their distinctive look because of the electron sea which surrounds the metal atoms?

are metals shiny because of the electron sea which surrounds the atomic lattice of the metal sample. are metals more shiny because the electron are more evenly distributed on the surface?
2
votes
2answers
45 views

Is an object's color/shine/texture dependent on its electrons only? If electrons are same then why are there so many different colors?

when we look at an object be it a metal or a non-metal are we looking at its electrons only, so then if all electrons are same then why do different chemicals or elements or objects have different ...
0
votes
1answer
27 views

internal conversion and the electromagnetic force

I have read that the mechanism behind internal conversion, in which a nuclear transition leads to the ejection of an electron in one of the lower atomic orbitals, is related to the fact that the ...
1
vote
1answer
33 views

What causes the triplet state in Helium?

I am not familiar with the notation used on wikipedia (http://en.wikipedia.org/wiki/Triplet_state). Is there a more physcial way to explain the cause of the triplet state (maybe without referencing ...
1
vote
1answer
43 views

Any simple reason why Helium in the ground state is diamagnetic?

I know the electrons are in the spin singlet state, and the spatial part of the wave function is an S-state. But that is not sufficient for it to be diamagnetic.
0
votes
0answers
25 views

Computing fine structure of terms in LS coupling,

In order to compute the fine structure of the terms in LS coupling (Russell-Saunders coupling), we must treat the hamiltonian $$H_2 = \sum_{\mbox{open subshells}} \xi(r_i) \vec{l_i}\cdot\vec{s_i}$$ ...
0
votes
2answers
37 views

Atomic physics - photoelectric emission

I understand that when photoelectric emission occurs: $$h\nu = h\nu_o + K.E.$$ Where $\nu_o$ represents the threshold frequency. What I don't understand is what happens if the frequency is just equal ...
0
votes
0answers
14 views

Why photoelectron imaging is a 'complete' measurement?

In many articles and books, it says that photoelectron imaging gives a 'complete' information. What is mean by 'complete' measurement or a 'complete' information? Through photoelectron imaging ...
1
vote
0answers
26 views

Most atoms have a nonzero magnetic moment, right?

This is my feeling. But more is different. If atoms form a solid, it is hard to say whether the solid will be ferromagnetic or not.
0
votes
1answer
540 views

What does the Atomic Form Factor means?

I was reading about Nuclear Physics and the autor mentioned something about the Atomic form factor, something relationated with the Fourier Transform of the espacial distribution of the electric ...
0
votes
1answer
38 views

Can an object be deconstructed on an atomic Level?

Can a machine deconstruct objects on an atomic level. But is that possible? Not the machine per say but the simple (not that simple) act of what it does. Ex.Taking a broken computer and separating the ...
0
votes
1answer
82 views

Can a single atom explode?

Does the definition of an atomic explosion require the interaction of two or more atoms, or can a single atom be the source of an explosion? Another way of phrasing the same question. Can there be an ...
3
votes
2answers
43 views

How does gamma ray emission make an atom more stable? [duplicate]

One of the types of radioactive emissions is gamma emission. I understand how the other two types, alpha and beta, help to make the atom more stable. How exactly does gamma emission help to make the ...
5
votes
1answer
220 views

Advanced atomic physics: From Liouville Equations to the Bloch equations

I'm trying to derive the Bloch equations from the Liouville equation. This should be possible according to this paper, where it discusses higher order Bloch equations (second order spherical tensors). ...
0
votes
1answer
84 views

What is a real world application of Madam Curie's life work?

As in the title. I know she was working with radioactive atoms and she made huge progress in the field of physics. But where would you find the application of her discoveries in our world? Is it just ...
1
vote
1answer
58 views

Lifetime of 3d state shorter than 3s state in hydrogen atom

Can you say that the lifetime of the 3d state in the hydrogen atom is shorter than the one of the 3s state because the centrifugal energy associated with 3d is higher than the one associated with 3s? ...
1
vote
0answers
28 views

Covalent Bonds, Varities and Limits!

Related:http://chemistry.stackexchange.com/q/9459/ I was wondering, covalent bonds tend to share two electrons, apparently rarely more than three, and normally between two electrons. Can someone give ...
3
votes
0answers
65 views

What is a covalent bond?

What is a covalent bond, quantum mechanically? How does it hold the two atoms together, and at one point can you qualify the electron as being shated between two atoms, versus feeling attractive ...
1
vote
1answer
81 views

The degeneracy of the ground state

I wonder how can i know the degeneracy of the ground state of certain elements? I'm doing Boltzmann distribution problems, and I'm not sure what to do. I have to calculate ratio of ions in 3p ...
0
votes
1answer
22 views

Use microwave cavity in atomic clock

In most of the papers regarding atomic clocks, the author talks about a microwave cavity. In this box, all the unwanted frequencies of the electromagnetic radiation are absorbed and the other ...
0
votes
0answers
8 views

Dipole and multipole bound state anions: Do these bound electrons behave exactly like conventional electrons in the molecular orbitals?

Recently, I read about dipole and multipole bound anions. Dipole bound anions are those, if I understood correctly, when an electron is attached electrostatically on a neutral molecule which is polar. ...