# molecules's questions - Chinese 1answer

318 molecules questions.

### Radiation absorption by CO2 molecule in atmosphere

What kind of radiation (light) does CO2 molecule absorb -UV or IR? I've read that it's infrared however some sources suggest ultraviolet. If so, how might it be possible?

### 2 How do $H_2$ lamps work?

2 answers, 55 views electricity molecules
When a hydrogen ($H_2$) lamp is subject to a high voltage hydrogen atoms release energy in the form of light. Somehow $H_2$ is splitted. But... Why high voltage produce the dissociation? Does ...

### Scientific explanation for smell? [on hold]

1 answers, 95 views physical-chemistry molecules
This might be more on the philosophical side. We already know a lot about light. How it is generated and how it interacts with a material. Phenomenon such as Interference, Diffraction, the ...

### 5 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: $\sigma$=$E^{L+1/2}$. ...

### 3 How to understand the symmetry $\Sigma^-$ in the wavefunction of a diatomic molecule?

3 answers, 1.248 views symmetry reflection molecules orbitals
In Wikipedia (and elsewhere), a particular symmetry of the quantum system of a diatomic molecule is mentioned: symmetry under reflection along a plane containing the internuclear axis. The ...

### 2 Extra Degree of Freedom in Linear Triatomic Molecules?

Ok, there is a bit problem in understanding Degree of Freedom of Linear Molecules specially of Triatomic Linear Molecules. See, the DOF in general is given as $f=3N-k$. Here, N=Number of atoms in a ...

### -1 Commercially available material with highest density to cost ratio? [closed]

2 answers, 53 views mass atoms density molecules elements
What are the top 5 commercially available materials (not limited to just the elements) with the highest density to cost ratio? To point to an application, say that my goal was to mass produce a solid ...

### 10 Is the molecular term ${}^1\Sigma^-$ possible in a molecule?

The old question How to understand this symmetry in the wavefunctions of a diatomic molecule? explores how it is possible for a quantum state to have zero angular momentum about a given axis (giving ...

### 3 How does the graph of molar heat capacity point towards quantization of motion?

In the graph below, if we consider that the jumps are stepwise for a molecule, even then, how does it point toward quantization of vibrational and rotational motion? The thing it implies is that (...

### 3 How did we first discover oxygen exists as $\rm O_2$ and not just $\rm O$?

How did we first discover oxygen exists as $\rm O_2$ and not just $\rm O$ ? (similarly hydrogen as $\rm H_2$ and not $\rm H$) I vaguely remember knowing a story about how the chemical formula of ...

### 1 Does every force applied to a rigid(assumed) body results in strain (in molecular level)?

4 answers, 405 views atoms elasticity molecules
If force is applied to a rigid body and the body moves/remains still/vibrate or anything. But, we assume there is no strain. But, even if we can't see any strain in the naked eye, isn't there some ...

### How to write a wave function for two entangled photons in a (J,P)=($0$,+) state?

I'm studying some experiments using pairs of atomic photons, in particular those photons that are consequence of the $(J=0)\rightarrow(J=1)\rightarrow(J=0)$ cascade of calcium. All of them start ...

### 2 For a molecule, does the term 'thermal vibration' mean the same thing as 'molecular vibration'?

2 answers, 34 views atoms vibrations molecules
When speaking of a molecule, do both terms ('thermal vibration' and 'molecular vibration') describe the same thing, being the one and only periodic motion of the atoms within the molecule? Or, are ...

### 11 What is the resonant frequency of liquid water?

4 answers, 35.477 views water resonance molecules
I learned it's not 2.45 GHz. But what is it, then? In my failure to find the real value, I'm starting to wonder: does it even make sense talking about a resonant frequency of water molecules?

### 7 Classical theory fails to explain quantization of motions?

I understand everything written here. But the last point, I cannot get, at all. How does it point towards Quantization of the two motions, since the energy change is not sudden, but gradual? And if ...

### What is the difference between intermolecular (cohesive, adhesive) and van der Waals force?

I recently learnt that intermolecular force is the force of attraction between molecules and van der Waals force does the same so is there any difference ?

### 7 Why doesn't the ${\rm H}_2$ molecule have a permanent dipole while the neutral ${\rm H}\,{\rm\small I}$ has one?

According to the National Radio Astronomy Observatory, the $21\,{\rm cm}$ line of hydrogen can be emitted by the neutral hydrogen atom due to the magnetic interaction between the spins of the proton ...

### Proof of no. of degrees of freedom for $N$-atom molecule [duplicate]

How can we say that the no. of degrees of freedom for a $N$-atom molecule is $3N$? How to $\mathbb{prove}$ it? I have heard people saying that for each atom, there are 3-independent variables to ...

### 4 Simple question about molecules leaving a liquid at a temperature below the boiling point

My textbook asks the question why a liquid cools down when partial evaporation occurs just below the surface at a temperature below the boiling point. The answer is of course that only those ...

### How many Vibrational degrees of freedom does a diatomic/triatomic linear molecule have?

I looked it up and found the formula to calculate number of vibrational degrees of freedom.I got it how they came up with this formula. It was (3N-5) where N stands for total number of atoms in a ...

### 6 Water molecules on the Sun? How does that work?

1 answers, 118 views astrophysics temperature water sun molecules
I've been reading about water on the Sun. The water they talk about is supposedly in a gaseous state because the Sun is so hot. But I'm wondering how even that could exist. Wouldn't the extreme ...

### Equipartition of energy and degrees of freedom in Diatomic gas [duplicate]

Suppose we have a gas of $N$ diatomic molecules (ex $O_2$) with one-molecule hamiltonian being: $$\mathcal{H} = \frac{\vec{p}_1^2}{2m}+\frac{\vec{p}_2^2}{2m} + V(r_{rel})$$ Where $r_{rel}$ is the ...

### 2 How many elementary particles are contained in a molecule of $H_2O$?

I was wondering about how many elementary particles form up one molecule of $H_2O$. What I thought of is the following: Hydrogen : 0 neutrons, 1 electron, 1 proton; electron is elementary and proton ...

### 1 Actual Degree of Freedom of Diatomic Molecule

Ok, I have 2 very different values for degree of freedom(DOF) of diatomic molecules arising due to the difference in the vibrational DOF of the diatomic molecules. According to this DOF wiki page:- ...

### 1 O2 molecues speed in air, and their limit

Temperature is the proportional measure of kinetic energy of the random motion of the constituent micro particles in a system as per wikipedia. Now I understand that O2 molecules are randomly moving ...

### External Coulomb potential diverges for 3D molecules?

0 answers, 19 views coulombs-law molecules
I read in a paper that the external potential diverges for 3D molecules, but I don't really understand what does this mean. In the paper, the objective is to build feature vectors for the external (...

### 1 If I would let something mix in the blender and let time go to infinity, will all molecules be separated eventually?

2 answers, 50 views atoms molecules
Just question out of curiosity. If I would let something mix in the blender and let time go to infinity, will all molecules be separated eventually, i.e. if I open up the blender it will be gas? Or ...

### 1 Symmetry of ground state electron configuration

1 answers, 38 views quantum-mechanics symmetry molecules
Take a molecule, whose atoms have a symmetry $S\in \text{O}(3)$ (i.e. S permutes the atoms). $S$ also acts on the wavefuncion $\psi(x_1,...,x_n)$ of the $n$ electrons in the molecule, by its action ...

### 1 Can we (in principle) obtain molecular bound systems by modelling fundamental particles and their interactions?

Is it possible, at least in principle, to start with the Schrodinger/Dirac/Klein-Gordon equations to model elementary particles and their interactions and to obtain in the end molecular bound systems? ...

### 1 Solving linear response in frequency domain

My question stems from a derivation given in chapter 12 of R. McWeeny's Methods of Molecular Quantum Mechanics for solving linear response equations via variational perturbation theory. (Linear ...

### Determining the sign (+/-) of the total work done on separating two molecules along a certain distance - AMBER16

I am currently moving two sugar molecules apart and would like to analyse the work done on separating them (and thus moving them apart from a distance of 3.5 Å to 30 Å). The values I am given by this ...

### 2 Existence of an electric/magnetic dipole of a molecule

I have a molecule with a symmetry group $S_3=D_3$. I have to determine if it has a non-zero electric and/or magnetic dipole moment using the representation theory. I'm using the book of Jones "Groups, ...

### What is the difference between a rigid diatomic molecule and non-rigid diatomic molecule?

1 answers, 1.107 views thermodynamics vibrations molecules
I started a mock paper for one of my entrance exams with this fairly easy question. I rearranged the equation and got 5/2, knowing that a diatomic molecule has a Cv of 5/2, i concluded that the answer ...

### 1 What does this notation mean: $\mathrm{O}_{2} \ \ a\,{}^{1} Δ_{g} ← X\,{}^{3}Σ^{-}_{g}$?

The notation (which I found in the abstract of this paper) is $$\mathrm{O}_{2} \ \ a\,{}^{1} Δ_{g} ← X\,{}^{3}Σ^{-}_{g}.$$ Any help with this? I understand it's talking about quantum states of ...

### 1 Under what conditions can molecules exist?

I am curious to know the conditions required for any two or more atoms to bond together and form a stable molecule. Is their a set of rules that should be satisfied?

### Simulating only small parts of macromolecules

0 answers, 8 views molecules molecular-dynamics
I've recently gotten into molecular dynamics (MD), and I was wondering the following: how can one simulate only small parts of proteins, e.g. up to 10AA? I am fond of e.g., Gromacs, where whole ...

### Surface tension molecular theory

1 answers, 24 views water surface-tension molecules
How does the surface of water behave like a stretched membrane? What's the cause for that? I know that the surface molecules experience a net force downward so there is dense layer of water molecules ...

### Does a Conical Intersection imply that the HOMO-LUMO gap in a molecule is very small?

0 answers, 18 views biophysics molecules quantum-chemistry
I came across some notes in which the author swiftly made this comment, that if there's always a large gap between the HOMO and the LUMO along a chemical reaction ("large" can mean at least bigger ...

### 11 Is Avogadro's law applicable for atoms or just for molecules?

I notice that online definitions of this experimental law always say, molecules or atoms. From the Wikipedia article on Avogadro's Law: $${\frac {V_{1}}{n_{1}}}={\frac {V_{2}}{n_{2}}}$$ The ...

### 16 Can a single molecule have a temperature?

A show on the weather channel said that as a water molecule ascends in the atmosphere it cools. Does it make sense to talk about the temperature of a single molecule?

### How can I know the volume occupied by one element in a compound?

I struggle to find how to estimate the volume occupied by one atom in a compound. As an example let's take $\beta$-Ga$_2$O$_3$, since that's the material on which I work the most. The crystal ...

### Where will pressure be stronger in these 2 pipe scenarios?

I initially started to be interested in fluid pressure and pipes to learn electricity. It seemed the only way I could help my head to get around some electrical concepts. That's the reason of my ...

### -2 Why do we measure boiling point of a liquid in an opened vessel [closed]

Can't we measure the boiling point of a liquid in a closed vessel

### Literature covering Hund's coupling case and anomalous Zeeman effect

I am taking a course in cold chemistry and different types of interaction seem to be an important cornerstone in the course. I am looking for a book that might cover the topics of molecules in ...

### 9 Can you make a metal denser by melting it and make it cool down under high pressure?

The answer is probably no. But can you make a metal denser by melting it and make it cool down under high pressure? Or would it just crack under internal stress when it returns to a solid? I'm going ...

### 10 Implications of parity violation for molecular biology

In biology, the concept of parity emerges in the context of chiral molecules, where two molecules exist with the same structure but opposite parity. Interestingly, one enantiomer often strongly ...

### Can I calculate the volume sputtering yield of a compound if I know the atomic component sputtering yields?

I'm running Monte Carlo simulations of a neon beam hitting a $\beta$-gallium oxide target. I set the initial bulk composition to be made of 40% gallium and 60% oxygen (Ga$_2$O$_3$). The simulations ...

### Is it possible to break a carbon dioxide molecule using electromagnetic waves?

I'm no expert in physics, but I was just wondering if breaking apart $\rm CO_2$ into oxygen and carbon would be possible using certain electromagnetic wave?

### 1 Bimolecular recombination in few words

I'm making a short seminar about VERY broad topic of fullerenes in photovoltaics, but I'd like it to be educational (not just full of words hard to audience to make them think I'm smart). In one of ...

### Pair correlation function vs Bond length distribution of a van der Waal dimer

For a weakly bonded molecular dimer (when two atoms are interacting through van der Waal (vdW) interaction). Do the distribution of pair correlation function and vibrationally average bond-length ...