hydrogen atom

kingyof2thejring

QW Why does the emission from hot hydrogen atoms consist of the Lyman, Balmer and Paschen series but the absorption of cold hydrogen atoms consists of just the Lyman series?
is it because the cold hydrogen atoms absorb characteristic frequencies and the lyman series involves transitions that start with the ground state of hydrogen.

cesiumfrog

I'm guessing it's because, say, the photon corresponding to a jump from level 2 to 3 can only be absorbed if some of the atoms are in level 2 to begin with.

jtbell

You got it! Cold hydrogen atoms are overwhelmingly in the ground state to begin with.