noun
spectral series
Technical term in physics for a set of spectral lines produced by electron transitions in atoms, such as the Balmer series.
水素原子のスペクトル系列は、バルマー系列などがよく知られている。
The spectral series of the hydrogen atom, such as the Balmer series, are well known.
スペクトル is the general term for 'spectrum', while スペクトル系列 specifically refers to a 'spectral series' of lines.
Compound of スペクトル (from English 'spectral') and 系列 (series, sequence).