This is my current drawing:
In my drawing the positive ion moves from the container on the left to the spectrometer on the right.
However, you said:
“1. Light coming directly from the ion is redshifted because the source (the ion) is moving AWAY from the receiver
2. Light going into the mirror has the same frequency as the light reflected from the mirror (due to the energy conservation). So, light reflected by the mirror into the receiver is blueshifted because the source (the ion) is moving TOWARD the mirror.”
And so I’ve changed my drawing:
(I changed the arrow on the moving ion from left to right to right to left)
Is this now right?
If so, then this clears up my red-shift/blue-shift confusion. Cool.
But, then … if this is correct … my basic understanding that the ion comes out of the container of gas … and so would then move from left to right is all askew.
My question (simple, like all of my previous ones): how does the ion end up moving from right to left? (This is so simple, I know it must be dumb.)