*Article* **The Frequency Fluctuation Model for the van der Waals Broadening**

**Andrei Letunov 1,2,\*, Valery Lisitsa 1,2,3 and Valery Astapenko 3**


**\***Correspondence: letunovandrey11@yandex.ru

**Abstract:** The effect of atomic and molecular microfield dynamics on spectral line shapes is under consideration. This problem is treated in the framework of the Frequency Fluctuation Model (FFM). For the first time, the FFM is tested for the broadening of a spectral line by neutral particles. The usage of the FFM allows one to derive simple analytical expressions and perform fast calculations of the intensity profile. The obtained results are compared with Chen and Takeo's theory (CT), which is in good agreemen<sup>t</sup> with experimental data. It is demonstrated that, for moderate values of temperature and density, the FFM successfully describes the effect of the microfield dynamics on a spectral line shape.

**Keywords:** spectroscopy; stark broadening; atomic physics
