A line spectrum is a spectrum consisting of discrete bright lines at wavelengths characteristic of a particular element, with dark gaps in between. The lines arise when electrons make transitions between specific energy levels, emitting photons of definite energy. Because the pattern is unique to each element, a line spectrum acts as a 'fingerprint' for identifying it; this contrasts with a continuous spectrum, which contains all wavelengths.

线状光谱是由位于某元素特征波长处、彼此间有暗区相隔的离散亮线组成的光谱。这些谱线产生于电子在特定能级之间跃迁、放出确定能量的光子。由于其图样为每种元素所特有,线状光谱如同鉴别该元素的“指纹”;与之相对,连续光谱则包含所有波长。