Definition question about atomic fluorescence

[td21]

Does atomic fluorescence involve:
1. spontaneous emission (or only),
2. stimulated emission (or only)
3. change in magnetic quantum number $$\Delta m \neq 0$$

?
Thank you.
Rarely can I find a definition on the internet. My guess is that atomic fluorescence involves spontaneous emission only. Fluorescence seems to be a term accompanying spontaneous emission only (but not involving stimulated emission), as in chemical compounds; while atomic Fluorescence seems to be a subset of Fluorescence. Does it always involve a change in magnetic quantum number?

 

[td21]

I especially hope to know if it always involves a change in magnetic quantum number. Can the term
atomic fluorescence include spontaneous emission with no change in magnetic quantum number? Thanks.

 

[Zarqon]

I especially hope to know if it always involves a change in magnetic quantum number. Can the term
atomic fluorescence include spontaneous emission with no change in magnetic quantum number? Thanks.

I think a short answer to your question is: yes, spontaneous emission can occur without change in magnetic quantum number.

In fact, unless you specifically apply an external magnetic field, there IS no magnetic quantum number (I assume you mean the spin here?), and as such it cannot change. However, even in the case of an applied magnetic field, fuorescence can occur without changing the spin, since emission in a direction perpendicular to the magetic field quantization axis (and with a particular polarization) again cannot see the quantization axis and so cannot change the spin.

I tend to think of fluorescence as simply meaning spontaneous emission, regardless of the involved levels.