Understanding Hydrogen Selection Rules: Emission vs. Absorption and the p-Series

[M. next]

Please see attachment. What are the arrow heads supposed to mean? Only emission is allowed and no absorption?
I mean, selection rules allow Δl=±1. But the figure is saying otherwise.

I also read in another book, that the only series observed in absorption is that to the ground state, where it is called the p-series.

Please explain, I am kind of lost in figures and resources.

 

[mfb]

The image is drawn for emission only - absorption is possible, too, if you have some source of light. The combination of excited atoms plus light of the right frequency for a transition can be rare, however.

 

[M. next]

But if I reversed the arrows in this figure so that I aim to draw a figure of absorption, all drawn lines will be possible, no?
(i.e, if I reversed the heads with tails of all arrows presented in the figure).

 

[mfb]

They are possible, but you won't see most absorption lines if you shine light on hydrogen in its ground state.

 

[M. next]

Ok, thanks, I just wanted to make sure of they were possible! As selection rules explain. Thanks again.