atomic element

So far,as an examp1e, many energy levels in the first spectrum of uranium (U I) have not been classified definitely according to their electronic configurations.

作为重元素原子光谱按电子组态类型分类研究的一个代表,铀元素原子第一光谱(UI)中的许多能级其所属电子组态尚未明确指认。