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1answer
503 views

Wigner Threshold law in Photodetachment and Photoionization

I am writing this question here because I have a problem in understanding the Wigner Threshold law in Photodetachment and Photoionization. The Wigner Threshold Law is given by: $\sigma$=$E^{L+1/2}$. ...
2
votes
1answer
160 views

Para and ortho hydrogen angular momentum values

In Wikipedia, it is said that: Orthohydrogen, with symmetric nuclear spin functions, can only have rotational wavefunctions that are antisymmetric with respect to permutation of the two protons. ...
2
votes
1answer
138 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 ...
1
vote
1answer
64 views

How to calculate the potential energy of an $H_2$ molecule

From left to right, electron $e_1$, $e_2$ and proton $p_1$, $p_2$. $r_0=0.529nm$ The total energy is sum of energy require to bring each particle to its place. Take the place of $e_1$ is zero ...
1
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1answer
336 views

Why is the orbital angular momentum of a pi electron along the axis of two atoms' molecule one?

I'm reading quantum chemistry. The book says that the orbital angular momentum of a $\pi$ electron along the symmetry axis of a molecule made up of two atoms is $\pm 1$. I think this is a primary ...
0
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1answer
69 views

How to determine rotational energy of gas molecules

For an arbitrary polyatomic molecular gas, what is the expected behavior of $U_{rot}(T)$, the rotational kinetic energy of the atoms, in the two limits T high and T low? So far, I have written an ...
0
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1answer
68 views

Along with electrons, do molecules also directly take in photon energy from a source?

Let's take a black object for example. When waves of light (whether from the sun or a lamp) come into contact with the object, is it just the electrons (not the molecules) of the object that directly ...
-1
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1answer
132 views

What is opposite of electric field?

A negatively charged molecule will generate a field, an electric field, and it will repel all negative ions. So what does positively charged molecule generates that causes other positive molecules ...
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0answers
49 views

What is the max frequency of sound in a given medium?

When talking about acoustic waves, medium continuity (pressure, density) is implicit. But can the wavelength of an acoustic wave be as small as intermolecular separation? For example, can ~10 THz ...
4
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0answers
268 views

Electron hopping among molecules - Marcus equation

I'm running out of professors to talk to, and I need to clarify a couple of things for the sake of making a realistic model of electron travel through a mesh. This is about calculations of electron ...
3
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0answers
38 views

If 2 fermionic atoms form a molecule, will the molecule always behave as a boson?

2 fermionic atoms give a bosonic molecule. 2 bosonic atoms form a bosonic molecule. Is there a energy scale where these two molecules will behave differently? If yes, will it depend on the ...
3
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0answers
106 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 ...
3
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0answers
135 views

Is the translational information all that matters, or do we need to take into account internal states?

For anyone in this community that's familiar with quantum teleportation, I need desperate help. I am currently working on my senior thesis and my goal is to teleport a molecule. Background: So in ...
2
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0answers
38 views

Plasmon quenching vs plasmon decay. What is the difference?

I'm reading an article "Quenching, Plasmonic, and Radiative Decays in Nanogap Emitting Devices" (pubs.acs.org/journal/apchd5). I don't understand the following: Counterintuitively, we evidence ...
2
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0answers
39 views

Why is CO a good tracer for H2? How are those molecules correlated?

One always reads and hears that CO is a good tracer for H2. How are they correlated? How can you deduce from the (measurable) CO the amount of the (unmeasurable) H2 in the ISM?
2
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0answers
86 views

Why is the activation energy of combustion so large compared with regular bonding?

I wanted to know why combustion requires an activation energy and I found this article (see this too). It says that molecular oxygen ground state is a triplet state (according to Hund's rules), and ...
2
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0answers
59 views

Why is the water diamagnetic?

I checked using my permanent magnet that water is diamagnetic. But why is it like that? Does this have any important consequence for life?
2
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0answers
61 views

How did Lord Rayleigh find the volume fraction of argon to air?

In order to isolate for pure nitrogen, Lord Rayleigh and his colleagues took some air and removed oxygen, carbon dioxide, and water vapour, leaving behind what he believed to be pure nitrogen. In ...
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0answers
38 views

Why is the potential minimum of a molecule shifted towards greater nucleii separation for excited electron states?

I know it has to do with symmetry of the wave function, but I am having trouble piecing it all together. For a positive H ion we have a symmetric wave function $\psi_{+}$, which base functions ...
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0answers
74 views

Bond Angle in a water molecule

I recently started up reaching up on the Feynman lectures on Physics and in Vol I,Chap 1-2,Feynman states that the bond angle between the hydrogen and oxygen atom is 105° 3′. I know that the bond ...
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0answers
47 views

Books on collision probability and collision processes

Are there any books specifically on collision processes between atoms and molecules and collision probability? I would like to get an overview of the factors that determine collision probability ...
1
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0answers
310 views

Why and how will the string break?

While i was searching on the identity discussed earlier that is $$1 + 2 + 3 + 4 + 5 + ... = -\frac{1}{12}$$ I found a similar identity applied to physics concept. It started by arranging long ...
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0answers
137 views

How large must the Quantum teleportation fidelity have to be in order for it to be useful?

This question relates and stems from my original question. Please read this one and the comments before answering this question. Quantum Teleportation Fidelity I know that for discrete variables ...
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0answers
16 views

Application of the Mean Field Approximation for molecules

When I studied the Ising Model in a course on Statistical Physics one approach that was presented was to use the Mean Field Approximation. In the ocasion I've noticed that it is also called "molecular ...
0
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0answers
15 views

Average Rate of Evaporation of Water

Consider a container of volume $V$ and cross sectional area (exposed to another fluid, say air) $SA$. The container is at constant temperature $T$, and contains $N$ molecules of water, where $N$ is ...
0
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0answers
33 views

how can VOC filters work given that atmosphere has 1800 ppb methane?

I have an IQAir HealthPro 250 air purifier that has a 2.5 kg activated charcoal volatile organic compound (VOC) filter. According to the manufacturer, the replacement interval is from 12 to 24 months. ...
0
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0answers
12 views

Can the atomic vibration of molten liquids be decomposed into a superposition of a series of normal modes?

From what I've learned, molten liquids have short-range periodicity (short-range doesn't just apply to the amorphous solid state/glassy state). So does this mean that, along with amorphous solids, the ...
0
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0answers
35 views

Can a buckyball gun be fired by observing it?

If a buckyball was placed inside a gun made from maybe a carbon nanotube or something, would measuring the momentum of the buckyball cause the the gun to fire? At what speed would the buckyball exit ...
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0answers
58 views

Can a molecule be ionized by absorbing the energy of more than 1 photon?

I'm wondering if a molecule can absorb more then 1 photon before releasing a photon. The reason I'm asking is I would like to ionize a molecule with light but the frequency of light this molecule ...
0
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0answers
55 views

Difficulty in understanding Maxwell Boltzmann distribution in case on ions in a field

I learned that the velocity of molecules obey Maxwell Boltzmann (MB) distribution at a Temperature T. If I have ions of mass 'M' accelerated to 2eV in a specific region. As the ions are not ...
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0answers
9 views

debris removal by electrification

Often during the lifetime of equipment, there is debris or residue accumulation on surface of, for example nozzles. This material accumulation can be quite strong. What kind of forces are they ...
0
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0answers
31 views

How do you calculate the optical contact bonding force of 2 1 meter by 1 meter perfectly flat surfaces?

Optical contact bonding is a phenomenon in which two perfectly flat surfaces will stick together, held purely by intermolecular forces. The trouble is, is there a way to calculate the pressure between ...
0
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0answers
65 views

What is the largest atom with a reliable configuration-interaction (CI) calculation?

The simplest approximation for calculating the ground state of an atom is the Hartree-Fock approximation. To get accurate result for the ground state energy, one has to do configuration-interaction ...
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0answers
50 views

Is it possible to get the (Pauli) repulsive term in the Lennard-Jones potential from theoretical considerations?

Title says it: Is it possible to get the form of the (Pauli) repulsive term in the Lennard-Jones potential from theoretical considerations, or is it purely found experimentally through fits?
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0answers
71 views

matrix elements of the electronic molecular Hamiltonian between a hartree product and a Slater determinant

This may belong in Chemistry, but I thought I might try my luck here first. In Szabo's book, an exercise requires a proof that = (N!)^(1/2) * given that |K(HP)> is the Hartree product wave ...
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0answers
169 views

Creep of materials at atomic/molecular level under stresses

Do the viscoelastic materials creep at the same rate under three types of fundamental stresses, viz.- TENSION, COMPRESSION and SHEAR??? My intuition tells me that the answer is no. But, I can't get ...
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0answers
47 views

Are there examples of “loss-less” Forster Resonance Energy Transfer (FRET)?

When I think of a Forster Resonance Energy Transfer (FRET) process, I typically imagine the initial excitation of an absorbing chromophore with a photon followed by the subsequent emission of a lower ...
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0answers
396 views

Saddle point and transition state of a molecule

During a transition of a molecule from one state to another, it pass through a transition state. This transition state, mathematically speaking, is a saddle point. That means, the second derivative ...
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0answers
308 views

Breaking of a covalent bond

When a bond between two atoms is broken, why only one electron is released. Why not two? (as two electrons make up a covalent bond.)