noun
mass spectrum
Technical term in analytical chemistry and physics; a plot of ion abundance versus mass-to-charge ratio.
質量スペクトルを解析して化合物を同定した。
We identified the compound by analyzing the mass spectrum.
質量分析 is mass spectrometry (the technique), while 質量スペクトル is the resulting spectrum.
Compound of 質量 (mass) and スペクトル (spectrum), a direct borrowing from English 'mass spectrum'.