Total Angular Momentum of Circularly Polarised Light


by nla7
Tags: angular, circularly, light, momentum, polarised
nla7
nla7 is offline
#1
Feb11-13, 09:53 AM
P: 2
I am considering the occurence of an incident circularly polarised EM wave on a ground state hydrogen atom. The result is that the final state of the atomic electron transition will be at m= 1 depending on the orientation of polarisation (LCP or RCP).

I understand that this is due to the conservation of angular momentum. The EM wave carries total angular momentum J of hbar. J also equals L+S (orbital angular momentum & spin angular monetum respectively). However the angular momentum of circularly polarised light comes solely from the spin angular momentum, which would imply that L=0 and S= hbar.

My problem is tho, is that S=m_s hbar and I understood that m_s could only equal 1/2. So how in the instance of my light, can S be an integer value of hbar?

Any assistance would be much appreciated. Thanks :)
Phys.Org News Partner Physics news on Phys.org
Physicists consider implications of recent revelations about the universe's first light
Vacuum ultraviolet lamp of the future created in Japan
Grasp of SQUIDs dynamics facilitates eavesdropping
mfb
mfb is offline
#2
Feb11-13, 12:33 PM
Mentor
P: 10,840
Unlike electrons, photons have spin 1, so m_s = +-1.
Meir Achuz
Meir Achuz is offline
#3
Feb11-13, 03:41 PM
Sci Advisor
HW Helper
P: 1,937
The m=+1 or -1 is for L_z of the orbital angular momentum of the electron.

nla7
nla7 is offline
#4
Feb11-13, 04:03 PM
P: 2

Total Angular Momentum of Circularly Polarised Light


Thank you. That makes sense now :)

I'm thinking that although it is the S component of the photon's J that has a value, because of spin-orbit interaction, it is only J that needs to be conserved and not the individual components S or L. Which is why it can be the electron's L that carries the conservation.
andrien
andrien is offline
#5
Feb12-13, 04:50 AM
P: 985
one more thing,photons are massless then don't have a zero value for m.


Register to reply

Related Discussions
Total angular momentum OP Advanced Physics Homework 3
total angular momentum of a sphere that had both a linear v and an angular v? Introductory Physics Homework 1
Measuring components of circularly polarised light. Classical Physics 1
[qm]find the angular opertor given total angular momentum wavefunction Advanced Physics Homework 13
Total Angular Momentum Introductory Physics Homework 1