**3. Main properties of the experimental fluorescence and absorption spectra of Cs atoms confined in nanometric cells**

As above mentioned, in the conventional thermal cells the different hyperfine Cs transitions starting from single ground level Fg are completely overlapped and cannot be resolved at all. Consequently, the application of the nanometric cell provides a new opportunity for significant enhancement of the resolution in laser spectroscopy of thermal cell, without application of complex atomic beam or laser cooling systems. Moreover, this simple tool makes it possible to study also the dynamic processes in the absorption and fluorescence, as well as in the electromagnetically induced transparency and absorption.

## **3.1 Sub-Doppler resonances in the absorption (transmission) of confined in nanometric cell atoms – Experimental observations**
