In the article “A Systematic Method for Determining Molecular Term Symbols for Diatomic Molecules Using Uncoupled-States Orbital Diagrams” in this Journal, Campbell introduced a systematic method to determine the molecular term symbols for diatomic molecules. This method is introduced in various undergraduate Physical Chemistry textbooks because of its practicality. However, there remains one question that may baffle some students: Why is |M_L| = Λ used when determining the molecular term symbols whereas it is |M_L| ≤ L for atomic term symbols? This letter aims to provide a more comprehensive yet clear answer to this question, which, I hope, will help students better understand molecular term symbols and polish their creative problem-solving skills.

中文翻译：

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关于教授分子术语符号：从二维世界中的原子术语符号到三维世界中的分子术语符号

在本杂志的“使用非耦合态轨道图确定双原子分子的分子术语符号的系统方法”一文中，坎贝尔介绍了一种确定双原子分子的分子术语符号的系统方法。由于其实用性，该方法已在各种大学物理化学教科书中介绍。但是，仍然存在一个可能使某些学生感到困惑的问题：| M _L |为什么？=Λ，用于确定分子术语符号，而| M _L | ≤大号用于原子术语的符号？这封信旨在为这个问题提供一个更全面，更清晰的答案，我希望这将有助于学生更好地理解分子术语符号并完善他们的术语。创造性的解决问题的能力。