unbound particle

例句：

1. 1.The unbound particle can be used to describe a particle that is not bound by any force or law.
   这个无约束粒子可以用于描述一个不受任何力或规律约束的粒子。
2. 2. In quantum mechanics, an unbound particle can exist in multiple states simultaneously.
   在量子力学中，一个无约束粒子可以同时存在于多个状态。
3. 3.The unbound particle is a fundamental concept in the study of particles and their interactions.
   无约束粒子是研究粒子及其相互作用的基本概念。