How can be spectrum of hydrogen measured (Lyman series, Balmer series, Paschen series and so on)? I mean schema of measurement circuit and the measuring technique (including all the steps needed). Is there difference between spectrum of atomic and molecular hydrogen?
googling "introduction to experimental atomic spectroscopy" gives some pretty nice results.
And yes, the spectrum of atomic and molecular hydrogen is radically different. This question at physicsforums correctly points the user to the NIST spectra database.
One should keep in mind that not all of the possible emission/absorption lines will show up in any given experiment and a lot depends on the exact conditions the gas is in. A nice introduction to this is in Condon and Shortley.