First there was the observation by Michelson who back in the late 1880s had done very precise interferal metric measurements of the hydrogen lines and had observed that the 656 nanometer line 3 associated with the transition of n equals 3 to n equals 2 was, in fact, a doublet.

首先是麦克逊,在1880年底的观察,他以公制单位对氢原子的光谱线,作了准确的，无其他因素干扰的，测量,发现当n值由3变为2时,会同时得到波长为656纳米的谱线3,实际上是有两条线。

麻省理工公开课 - 固态化学导论课程节选

He measured the line spectra of atomic hydrogen.

测量了氢原子的线光谱。

麻省理工公开课 - 固态化学导论课程节选

Now if you read in the book, you read about where this figure is shown in the book, you can understand more about why these structures line up in the right way so that the right molecular elements are together to form hydrogen bonding pairs between them.

如果你预习过课本,课本中有关于这些详细的描述,你可以更深刻的理解,为什么这些结构是采用这种连接方式,以使对应的分子部分靠近,并形成氢键连接

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You do not get this line from molecular hydrogen.

从氢分子中我们得不到这种光线。

麻省理工公开课 - 固态化学导论课程节选