free-atom cross-section

例句：

1. 1. Thestudy of free-atom cross-sections is crucial for understanding the behavior of atoms in different environments.
   研究自由原子截面对于理解原子在不同环境中的行为至关重要。
2. 2.In the early days of quantum mechanics, scientists were puzzled by the concept of free-atom cross-sections.
   在量子力学的早期阶段，科学家们对自由原子截面的概念感到困惑。
3. 3. The measurement of free-atom cross-sections has become a powerful tool for studying the properties of materials.
   测量自由原子截面已成为研究材料性质的一种有力工具。