Spectral line changes?

[[Mod. note -- This query started out over in our sister newsgroup
sci.physics.research, but was moved here at my request. This article
should probably have been crossposted between the newsgroups, but I
didn't think of that at the time. Oops...
-- jt]]

Question: Is the spectral line signal for hydrogen different for
hydrogen in hydrogen gas compared with hydrogen in water?

Or, if one were observing the spectral line for some distant
collection of hydrogen gas and then that gas reacted with some
sudden supply of oxygen forming water, would or does the spectral
signal change?

Thanks, in advance.
Ralph Frost