en Research Paper Research Paper <div style="text-align: justify;">Thin films of meta-cinnabar mercuric sulfide (&beta;-HgS) nanoparticles (NPs) was prepared by pulsed laser ablation (PLA) utilizing a pellet of cinnabar mercuric sulfide (&alpha;-HgS) was immersed in distilled water (DW). Q-switched Nd:YAG laser of 1064 nm wavelengths with repetition rate (1hz) and fluency (1.5 J/cm²) applied for ablation. Structural, morphological and particle sizes of the &beta;-HgS NPs are invastigated by analyzing XRD, AFM, SEM and TEM measurements. Their crystal structure is transformed from hexagonal (wurtzite) of the &alpha;-HgS target material to cubic (zinc blende) &beta;-HgS NPs. The optical properties of the &beta;-HgS NPs are measured by UV&ndash;visible spectrophotometer. The direct band gap is calculated to be (2.45eV) of small particles (4-6.2nm) moreover, the band gap value of smallest particles (1-4nm) is (3.47eV) according to the optical transmission spectra</div> Pulsed laser ablation,Nanocrystalline,Mercury sulfide,Cinnabar,Metacinnabar. 11 16 http://ijmse.iust.ac.ir/browse.php?a_code=A-10-2302-1&slc_lang=en&sid=1 N. Mohammed nadph73@gmail.com 1800319475328460010616 1800319475328460010616 Yes Assistant professor, Thin Films Laboratory, College of Science, Mustansiriyah University, Baghdad, Iraq H. f. Dagher 1800319475328460010617 1800319475328460010617 No