# Tag Info

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L-S coupling is the appropriate way of description of small small electronic configuration ($Z\leq10$). In case of atoms having a large number of electrons, J-J coupling works.

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As it turns out, the excited states of an atom are not quite eigenstates. That is, they're eigenstates of the atomic hamiltonian, but they are not eigenstates of the atom-plus-EM-field hamiltonian. How do we know? If you prepare them (excited atom, empty field) and then you leave them alone, they change, so they can't be eigenstates. What they are is ...

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If I understand your question correctly, you are confusing between two definitions of "width". One is the spread of the spectral line and the other is the lifetime of the atom in excited state. Well, these two are related(as you guessed) by uncertainty principle. $\Delta E\,\Delta t = h/4\pi$. So if the time the atom spends in excited state is less, the ...

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Random thermal motion (Brownian motion) allows the particles to become ergodically distributed in the their phase space. They scattering off each other and any other particles in the environment, this randomises the motion. Otherwise they would carry on in the same direction until acted on my a force. It is the randomisation nature of scattering events that ...

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Nothing "causes" diffusion, it is a statistical process. The atoms in any system in thermal equilibrium are constantly moving with velocities of order $\langle v^2\rangle \simeq T/m$. This motion is randomized by collisions on some microscopic time scale $\tau$. The simplest case is a dilute gas, where $\tau\sim 1/(vn\sigma)$, where $n$ is the density of the ...

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Quantum tunneling keeps the energy of the tunneling particle the same as it had within the potential . As you will find, putting realistic numbers for nuclear penetration in the calculator of the link the probabilities come out zero. So spontaneous "turn into a nuclear bomb " is out. Lets took "technically" : A human exposed to MeV radiation can he/she ...

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The thing is, we're made of mostly stable matter of low atomic number. In a nuclear bomb, unstable nuclei split, releasing a number of energetic neutrons which strike other unstable nuclei, and the reactions chain uncontrollably. Splitting a small nucleus actually costs energy, so even if a carbon atom in your body did split, it would only split into ...

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It also appeared to me that the higher you go, the harder it is to make an element. This is pretty much true. I have a tendency to be wordy and long in my posts, but I'll try to cover a few points as concise as possible. Ununoctium was created by "bombarding atoms of californium-249 with ions of calcium-48. This produced ununoctium-294, an ...

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It's not a game of chance. Selecting the right nuclides for the heavy ion collisions is key and the detection requires extremely sensitive and well calibrated detectors. If you want to put an attribute on it then "art" would be far more fitting. You are correct, it does get harder for heavier nuclei. Practical applications? That's not a question for science, ...

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There are no random motions in solids. All motions are highly correlated, you are just adding up a lot of modes at different frequencies, which looks like random motion if you are only looking at a single atom. It's not totally wrong to look at single particles being in random motion, though, since the Fourier transform of a lot of frequencies at arbitrary ...

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The measurement of C-14 can be accurate. The interpretation of the measurement, in terms of the presumed age of the sample, is the thing that is subject to careful calibration. The assumption of carbon dating is that the ratio of C12/C13/C14 in the sample had some known value at the time the organism was alive. "Known" does not mean "constant over all ...

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It depends on the mechanism by which the photon is emitted. Stimulated Emission: Yes, the emitted photon will inherit the characteristics of the photon that stimulated it, including its propagation direction. That's how lasers get coherent light. Spontaneous Emission: No, this should be random orientation. Another way to think about spontaneous emission is ...

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In the general case, "no" as there is a angular momentum transfer involved (meaning there are preferred directions relative the original and/or final angular momentum of the atom). That said, for most matter at room temperature the atoms have random orientation so you can treat the answer as "yes" for experimental purposes. Now, I see that you are ...

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