# Tag Info

## Hot answers tagged atomic-physics

5

This is hard to answer conclusively but it feels like historical coincidence, coupled with the fact that it is a bit harder to use strong electric fields in a discharge tube without the electrodes sparking. Some points of note: The Stark effect was discovered after the Zeeman effect, but not very long afterwards: the Zeeman effect in 1897 and the Stark ...

5

Let's suppose the electron we are considering is in an orbital described by the wavefunction $\psi$. If we look in some small volume element $dV$ then the probability of finding the electron in that volume element is: $$P = \psi^*\psi \, dV$$ To calculate the probability of findng the electron inside the nucleus we'll use polar coordinates, and as our ...

4

You've been done a disservice if your earlier teachers didn't even mention the existence of Gaussian units (a cm-gram-sec system with "unrationalized" E&M). Not that I like them, but simply because they were very common in the mid twentieth century and they still have their adherents (some even on Physics SE). The unit of charge goes by several names ...

3

It means that both neutron shell and proton shell have been filled. Neutrons and protons have different isospin values, hence they can have all other quantum numbers equal. This means, in the context of Shell Model, that they will occupy different shells and the filling of neutron shells is independent from the filling of proton shells. Hence when a ...

3

I've cross checked it with some known isotopes which decay by Cluster Decay. It would appear to be that. I guess it stands for Cluster Emission.

3

I presume you are talking about spontaneous radiative transitions. If you allow stimulated emission or collisional de-excitation then obviously this depends on the external environment. The basic answer is that you have to do the calculation quantum mechanically. Some transitions are quick, but others (known as forbidden transitions) can be very long ...

3

The hydrogen atom has an infinite number or quantum mechanically allowed energy levels, as explained on this web page. Using that same link, scroll up the page a bit to better understand how transitions between these energy levels give rise to absorption or emission of photons of very specific frequencies. Then scroll further down to see how the hydrogen ...

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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, ...

3

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 ...

3

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 ...

2

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 ...

2

Why do heavy nuclei have half lives? To keep it simple -> Coulomb repulsion Why do heavy nuclei have half-lives if they are unstable why do they take millions of years to break down in some cases why don't they simple do it instantly? You cannot predict when one nuclei "breaks down". It can live forever. However, for a big sample you will have ...

2

Do electrons always have a probability of being somewhere [in] the same way as when they surround a nucleus? Yes. Of course they don't have a probability a of being somewhere when surrounding a nucleus, they have a frequency of being found somewhere if measured, which is different. You can get a full probability too, but only if you specify even more ...

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Screening means that from the view of the electron for which this is being calculated, the effect of the nuclear charge is lessened due to the other electrons which are orbiting the nucleus. In the first case, the K-shell electron is in the $1s$ orbital(which is spherically symmetric around the nucleus, and so it can effectively screen the nuclear charge ...

2

The discovery of the electron: II. The Zeeman effect http://dare.uva.nl/document/2/2775 "Lorentz’s theory was based on the assumption of the existence of charged vibrating particles inside atoms. Zeeman’s discovery, together with Lorentz’s theory, were the first indications of the existence of a new charged particle, later known as the electron." Perhaps ...

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Charge is a conserved quantity. If the incoming photon on a molecule is of the appropriate energy , an electron can be kicked from a low energy level to a higher energy level .Since the charge of the photon is zero , the molecule remains neutral. If the energy of the photon is high enough the electron gets kicked out, the molecule becomes positively ...

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Not even remotely possible. You would have to overcome the Strong Nuclear Force to rip a nucleus apart, and that is the strongest of all the fundamental forces. Here's a graphic from this site:

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I believe that a more important effect of using semicondctor detectors (Ge(Li), HPG, Si(Li) and others) in a neutron-ridden environment is the dislocation damage of the crystalline structure due to neutron irradiation. Dislocations in the crystal increase the charge carrier collection time and decrease the efficiency of charge collection. This results in ...

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http://www.nndc.bnl.gov/nudat2/indx_adopted.jsp Appears to be the answer I was looking for, if anyone else is interested.

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I learned to keep track of the conversion from SI to Gaussian units for electromagnetism as \begin{align} \frac{e^2}{[4\pi\epsilon_0]} &= \alpha \hbar c \end{align} where the factor in [brackets] is unity in CGS units and isn't in SI. This is a nice way to remember things because it makes clear that Coulomb's law for two fundamental charges,  \vec F = ...

1

At the atomic/molecular level all chemical reactions are Quantum Mechanical phenomena where atomic and/or molecular electron orbitals of the reactants are being destroyed and new ones created in the reaction products. This is what you are correctly referring to as formation of bonds (although it has to noted that some bonds are also broken during chemical ...

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I will turn my comment into an answer: One is dealing with classical physics in this question, at the level of the Bohr model for the atom special relativity is unknown. An inertial frame can be defined as a frame where the laws of physics have the same mathematical form and measurements in one inertial frame can be converted to measurements in another ...

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Contrary to @Gert 's answer, creation of photons from reactions forming and breaking chemical bonds (typically reactions between molecules) is quite rare. When photons do occur, it can be (1) the result of a molecule, atom, or structure created or altered by the reaction being in an electronically excited state, which then decays, emitting a photon. There ...

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Firstly radio-isotopes ('unstable' nuclei) show a very wide range of half-lives and each specific radio-isotope has a specific half-live. The range of half-lives varies from extremely small (milliseconds and smaller) to extremely large (millions of years in some cases). Stable, non-radioactive isotopes can be considered for simplicity sake to have half-lives ...

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