- #1
Fegito
Hi all, this is my first time posting so I hope it's in the right place, if not I apologise. I'm trying to understand the angular dependence in NEXAFS spectroscopy for linearly polarised light.
So from what I understand, the quantum mechanical description of the excitation process for a single electron in the dipole approximation, is given as |<ψi|e.p|ψf>| where e is the unit electric field vector and p is the dipole transition operator. In all the books/sites I have read it then states that for linearly polarised light, the matrix elements of interest take a simplified form, and can be written as:
|<ψi|e.p|ψf>| = e.|<ψi|p|ψf>|
It then goes on with the derivation, which is fairly straightforward What I don't understand is this seemingly simple step, more specifically why the electric dipole vector can be taken out front (I have no prior knowledge of quantum mechanics so there's a good chance it's something really simple which I'm just not understanding!). Would someone please be able to shed some light on this? Thanks in advance.
So from what I understand, the quantum mechanical description of the excitation process for a single electron in the dipole approximation, is given as |<ψi|e.p|ψf>| where e is the unit electric field vector and p is the dipole transition operator. In all the books/sites I have read it then states that for linearly polarised light, the matrix elements of interest take a simplified form, and can be written as:
|<ψi|e.p|ψf>| = e.|<ψi|p|ψf>|
It then goes on with the derivation, which is fairly straightforward What I don't understand is this seemingly simple step, more specifically why the electric dipole vector can be taken out front (I have no prior knowledge of quantum mechanics so there's a good chance it's something really simple which I'm just not understanding!). Would someone please be able to shed some light on this? Thanks in advance.