# Magnetic Quantum number

1. Aug 1, 2008

Being a student sometime i confuse about the real concept of magnetic quantum number.
Somwhere i percieved when orbit is introduced in external magnetic field then magnetic quantum number.But there is still magnetic field due to electrons as well?
I am confused about whole story?
Can anyone help me in this regard and please explain it in detail with most simple way.
Grateful to u

2. Aug 2, 2008

### malawi_glenn

The magnetic quantum number (the broken symmetry of spin and orbital 'motion') of electrons in atoms where found when you saw how they responded on magnetic and electric fields. The spectra splitting and Stern-Garlasch experiment just to name a few.

Magnetic field due to electron spins in a solid is called pauli magnetism.

Also there is coupling between the electrons spin in the atom, since classicaly a spinning ball will induce a magnetic field. That is why you call it spin, even thogh electrons dont have any size or are spinning in space (but that is another story hehe).

Also the magnetic quantum numbers falls out when you work out the mathematics of the angular momentum properties of quantum objects (the rotation groups).

Please tell us what you want to know more, maybe you are asking what is the micrsoscopic explanation for macroscopic magnetism?

3. Aug 7, 2008

Actually i am confused about the Orbital quantum number defination/description.
What it is ?Before describing orbital Magnetic quantum/spin magnetic quantum number we have to introduce atom in external magnetic field or we use the term magnetic for motion of electrons etc(of intrinsic motion of atom).Actually i confused about the term magnetic which come in these quantum number either coming when we apply any external magnetic field or this term is due to internal motions of atom which quantum number is discussing?
I will be thankful to u if u clear it for me with most simpleat way

4. Aug 7, 2008

### malawi_glenn

Well first, here you can see the mathematical derivation of orbital angular momenta in QM:

And here

The 'orbital magnetic quantum numbers' are there because of symmetry reasons. And in an unperturbet hydrogenic-like atom, the energy levels of each L will be degenerate (i.e same energy independent of $m_l$. But in the precense of a electric or a magnetic field, the energy levels will split up according to their $m_l$ values (see Stark vs. Zeeman effect). So this is why it is called 'magnetic QM #' due to its response to magnetic (-and electric) fields.

Also you can think of it classically, an orbiting charge will induce a magnetic field that will interact with other fields. But you have to take this to QM, where you have a probability distribution in 3D space. For $m_l = 0$ , the distrubution of electron probability will average to zero - so no interaction with the applied magnetic (or Electric) field.

Last edited by a moderator: May 3, 2017
5. Oct 8, 2008

Rempi

I know about REMPI scheme a little bit but i have some question about it.

In REMPI scheme we have to creat more photons in specific volume element/space means high intensity of Laser light we use there.For example (2+1) REMPI Firstly,a molecule absorbs 2 photons simultaneously and go to some intermediate electronic excited state and absorb third photon and become ionized.

My Question is how can analyse in any case either it is 1+1 REMPI or 2+1 REMPI or 3+1 REMPI or 2 photon transition.Who can we guess what type of REMPI?

Means How much intensity of light produce 1+1 REMPI and how much intensity of light produce 2+1 REMPI etc.

Sometime i think Might be only one way to guess this type of REMPI is to study the transition states of any molecule.

Can anyone help me in this regard to understand clear picture of REPMI phenomenon.
I will be thankful to u

6. Oct 8, 2008