Questions tagged [spin]

Spin is a type of angular momentum which is intrinsic to atomic and sub-atomic particles. Electrons in orbitals can be either spin paired or spin unpaired which influences the magnetic properties of the species containing these orbitals.

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42 views

Why is the sum of the square of the orbital coefficients 1

I'm reading up on molecular orbital theory and LCAO in Ian Fleming's "Molecular Orbitals and Organic Chemical Reactions" and I don't understand the logic here: "When there are electrons ...
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Reading materials about Spin 1 Systems in NMR

I am working on spin 1 systems and I came across this book Spin 1 NMR by Chandrakumar and chapter13 of Spin Dynamics. This book is good but i still have doubts pertaining to the system Hamiltonian ...
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Direction of spins in the singlet vs. triplet state

Suppose we consider the first excited state of the helium atom. We know that the first excited state of helium can exist as a triplet or singlet. The possible functions related to the spin of the two ...
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the ratio between high spin state and low spin state when they coexist

I am considering the spin state's effect on the charge carrier's lifetime, I was told that high spin and low spin state could coexist when the crystal field splitting energy and the pairing energy are ...
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How can I determine the spin of a molecule?

I was reading statistical mechanics today and came across a line For $\ce{O2}$ and $\ce{N2},$ we get half-spin, and that is why we get $σ = 2$ in their rotational partition equation. I didn't ...
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Spin Multiplicities of Ions

The multiplicity is fundamentally defined as $2S + 1$ where $S$ is the total spin. From what I understand, the multiplicity corresponds with the number of unpaired/paired electrons. For example, in ...
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What does "spin degeneracy" mean in this context?

I am currently studying Diode Lasers and Photonic Integrated Circuits, second edition, by Coldren, Corzine, and Mashanovitch. In chapter 1.2 ENERGY LEVELS AND BANDS IN SOLIDS, the authors say the ...
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2answers
228 views

Does an electron's spin change when being excited?

My preconception is that when you fill an empty orbital by exciting an electron (with a photon), the empty orbital should be filled by an electron with the same spin. However, I've seen examples of ...
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How to construct spin free coefficient of 2-hole 1-particle configuration?

It is clear that we can expand a cationic state of a molecule in terms of configuration interaction (up to double excitation). It means: $$|I \rangle = \sum_j c^{(I)}_j a_j|\phi_0 \rangle \ + \ \sum_{...
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108 views

How can an electron being a wave have such property as spin?

Here's what I know about electrons. Electrons have wave-like properties and the number of wavelengths in the $n^\text{th}$ shell is equal to $n(\lambda).$ Also, I read in my book that they have ...
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792 views

What does an electron's spin of 0.5 and minus 0.5 signify?

While teaching me magnetism, my teacher told me about the spin of an electron. He told me that the spin of .5 means that if we rotate the electron twice counter-clockwise on its axis, we would have ...
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Grasping the concept of Electronic Spin, Effective Spin and Fictitious Spin

Trying to learn alone some aspects of quantum mechanics is, sometimes, a struggle. Reading the excellent paper by Piwowarska [1] I was hoping to, finally, understand what is the origin of the so-...
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Difference between spin-orbit coupling and the Russell-Saunders Effect?

The Russell-Saunders effect is the same thing as 'spin-orbit interaction, correct? The reason I am asking is because I was reviewing the Wikipedia page on 'spin-orbit interaction' and it does not ...
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Methylene "anti" Jahn-Teller effect

Yesterday a Reddit user posted a page from Morrison's Organic Chemistry in which it is said that singlet methylene is less stable than triplet methylene. Another user asked basically the same I'm ...
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Mulliken Spin Density

I would like to know if a Mulliken population analysis to calculate spin densities is in general a valid choice. I see that it is made use of, for example here1. So up to-date researches apparently ...
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Effect of magnetization on oxidation (rusting) of iron

Can magenetizing a piece of iron bar slow-down (or speed-up) the oxidation (rusting) process? In other words have any influence on it ? From what I've looked up( wikipedia, quora), it appears that the ...
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What is the hybridisation of [Co(H₂O)₆]³⁺? [duplicate]

There's a lot of ambiguity in the hybridisation of $\ce{Co^3+}$ in its hexaaqua complex; is it a high spin or low spin complex? As theoretically the CFSE is less than P so it should be low spin, but ...
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What is diamagnetic in diamagnetic dilution?

I'm reading a paper where the authors study a peptide solution where each peptide may have two spin labels attached to them. They put the peptides on the surface and study them using a diamond sensor. ...
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103 views

Spin Operator algebra

I am trying to teach myself some QM. In Christopher J. Cramers textbook Essentials of Computational Chemistry: theory and models, in Appendix C, he goes over Spin algebra. I am unable to calculate ...
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T1 spin-lattice relaxation times, deviation from exponential relationship

For longitudinal relaxation, one would think that the magnetic moment obeys this simple relationship $$M_z = M_0\left[1 - 2\exp\left(\frac{-t}{T_1}\right)\right].$$ However there is always a point ...
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Sum of spins of electrons in a wavefunction

I wanted to ask a question about spin in an electron. We were presented earlier today with the following information: Using my synoptic knowledge, I recall that spin up $\alpha$ had a value of $+\...
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Ground state term symbol, why is $L = |M_L|$, if L must be a maximum?

I'm trying to understand how to predict ground state term symbol of atoms. After finding the biggest S, why the biggest L will be $L = |M_L|$, where $M_L = \sum m_l$? I know this rule works to ...
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How long would it take for a tank of same-spin hydrogen atoms to become a tank of H₂?

In the question Is there an energy cost associated with flipping the spin of an electron?, it is shown that it is very unlikely for two hydrogen atoms to bond if their electrons have the same spin. ...
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124 views

Electron Spin, and the Stern-Gerlach Experiment

I think I understand the basics of the electron spin. However, I'm trying to figure out how to tell if, when shooting a beam of atoms (the Stern-Gerlach experiment), how to tell if an element will ...
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Why draw "up" arrows first when filling orbital diagrams? [duplicate]

I am a 11th/12th grade student studying orbital configurations. I have gone over this lesson and it says to always draw spin up first. However, it never says why. Is drawing down spins first incorrect?...
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Why is it important to know the spin of bioinorganic complexes?

During a bioinorganic chemistry course, my teacher gives a lot of importance to spin states of metal ions and how they changes (or not) after the formation of a complex. For example, when hemoglobin'...
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238 views

How to calculate S² value of a broken-symmetry wave function?

$S$ represents spin, signifies the number of unpaired electrons in the system. For example, if the number of unpaired electrons is $1$, then $S=1/2$. $S^2$ is calculated as $S(S+1)$. From what I have ...
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What happens when para-water ice is suddenly melted?

Background (hydrogen) In the case of recently liquified hydrogen (which is quite cold of course) it must be re-equilibrated before loading on to a rocket as fuel to avoid a sudden exothermic ...
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54 views

Why ¹H–¹⁴N coupling is not observed in ¹H NMR

Since the nuclear spin value of $\ce{^{14}N}$ is $I = 1$, we should expect a coupling between $\ce{^1H}$ and $\ce{^{14}N}$. Hence, the proton peak in a primary amine $(\ce{-NH2})$ should split in a ...
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Is [Co(NH₃)₄Cl₂]Cl paramagnetic or diamagnetic?

$\ce{NH3}$ is known to be a strong field ligand, while $\ce{Cl}$ is known to be a weak field ligand. Is $\ce{[Co(NH3)4Cl2]Cl}$ a high spin complex or a low spin complex? I assumed this to be a high ...
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968 views

Only d orbital electrons for spin only magnetic moment

During my chemistry lessons and self studies, I have come upon many instances where I observed that during calculations of spin only magnetic moment of transition elements only the d orbital electrons ...
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252 views

Shortcut method to find atomic term symbols ignoring the spin orbit coupling

Is there any shortcut method by which we can find the atomic term symbols ignoring the spin-orbit coupling, i.e. ignoring the values of J. For instance, when writing the d-d transitions for any ...
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How is a NMR spectrum obtained?

I am reading about NMR, and from what I'm understanding it should give information on the transition energies in the spectrum of the nuclear spin in a magnetic field. What I don't understand is how ...
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NMR: How the relaxation times T1 and T2 depend on the correlation time / amount of molecular tumbling.

Why do nuclei that have a smaller / faster correlation time have a higher / slower T1 / T2? From my understanding: Fast Brownian motion creates a wide range of B.local (local magnetic field created ...
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64 views

Maximum metal-metal distance for antiferromagnetic coupling

Imagine a transition metal complex with multiple open-shell transition metal cations. If the metals are relatively close in distance, it is possible that antiferromagnetic coupling will occur between ...
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What is the magnetic moment of potassium hexacyanochromate(II)?

I calculated the magnetic moment of $\ce{K4[Cr(CN)6]}$? in the following way: $\ce{Cr^{+2}}$ has $4$ d electrons. And since $\ce{CN-}$ is a strong field ligand, the electrons will pair up in the $\...
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68 views

How to interpret a singlet term symbol for an s¹p¹ configuration?

I am interested in the $^1P_0$ singlet state of $\ce{Hg}$ ($\ce{5d^10 6s^1 6p^1}$). I interpret this to be the two following electron configurations below, because for an $S = 0$ state the two ...
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Help understanding the equation for Spin Energy in Zero Field

I’m working with a system that experiences spin frustration and for me this is the first time dealing with such a phenomenon. To grasp the concept, I’ve decided to go to the basics and read the ...
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Determining absorption spectrum, magnitude of Δo and spin for Iron Oxalate

Iron Oxalate ions form an emerald green solution when dissolved. If the ions in solution appears emerald green to our eyes, what color of visible light is it mostly absorbing? What does that tell you ...
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221 views

Distinguish between two possible configurations for angular momentum in carbon atom

Consider the possible values of $S$ and $L$ for carbon configuration $1s^2 2s^2 2p^2$ and the corresponding rapresentations with arrows indicating the spins (consider only $S=0,L=0$ and $S=0,L=2$, as ...
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Why is spin-contamination undesirable?

Why is spin-contamination, introduced by e.g. Unrestricted Hartree Fock, undesirable, and to which problems further on can it lead? The only problem I currently see myself is that spin-contamined ...
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448 views

NMR - coupling of chemically equivalent protons

In Klein's Organic Chemistry 3rd Edition page 671, it states This observation, called the n + 1 rule, only applies when all of the neighboring protons are chemically equivalent to each other. ...
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780 views

Why is a spin change favourable in intersystem crossing?

All phosphorescent molecules go through the following transitions: $$\text{excited singlet state}$$ $$\Bigg\downarrow$$ $$\text{[intersystem crossing]}$$ $$\Bigg\downarrow$$ $$\text{ excited triplet ...
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Help understanding external magnetic field sensitivity of radical pair reaction rate

Two recent papers have been published on magnetoreception in birds. In this case it is the ability of the birds to sense the direction of the Earth's magnetic field potentially for navigation. ...
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Total spin number 0 together with $B_2$ state - confusion

I'm trying to understand molecular symmetry and I got confused reading the Molpro documentation. There is an example of a system with $B_2$ symmetry written like this: $$ wf,10,3,0, $$ which means, ...
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How to calculate the spin of atomic nuclei?

I have recently been learning about nuclear magnetic resonance spectroscopy. It is mentioned that the spin of the $^{1}$H nucleus is $\frac{1}{2}\ $and the spin of the $^{2}$H nucleus is $1$. This ...
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How to derive Pauli Exclusion Principle without assuming anti-symmetry?

So, it appears that the statement of the Pauli Exclusion Principle is equivalent to the statement that fermions are anti-symmetric. That is, if you assume that fermions are anti-symmetric, then you ...
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Which electron is knocked off a Helium atom?

When a He atom is ionized, which electron is removed first, the one with the spin up or down? or is it just random?
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"Hamiltonian operator has no effect on the spin function" what does it mean?

I have read the Levine Quantum Chemistry book and it says "Hamiltonian operator has no effect on the spin function" in chapter 10 (Electron Spin and the Spin-Statistics Theorem) and does the ...
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400 views

Are electrons in a helium atom diametrically opposite? [closed]

The helium atom is represented with electron opposite on same orbital: not fully opposite on same orbital and even on two normal orbitals: But in this case wouldn't the electron crash? Can you ...