The fundamental momentum conservation requirement q ~0 for the Raman process is relaxed in the nanocrystallites(NCs),and phonons away from the Brillouin-zone center will be involved in the Raman scattering,which is well-known as the phonon confinement effect in NCs.This usually gives a downshift and asymmetric broadening of the Raman peak in various NCs.Recently,the A’_1 mode of 1L MoS2 NCs is found to exhibit a blue shift and asymmetric broadening toward the high-frequency side[Chem.Soc.Rev.44(2015) 2757 and Phys.Rev.B91(2015) 195411].In this work,we carefully check this issue by studying Raman spectra of 1L MoS2 NCs prepared by the ion implantation technique in a wide range of ion-implanted dosage.The same confinement coefficient is used for both E’ and A’_1 modes in 1L MoS_2 NCs since the phonon uncertainty in an NC is mainly determined by its domain size.The asymmetrical broadening near the A′_1 and E′ modes is attributed to the appearance of defect-activated phonons at the zone edge and the intrinsic asymmetrical broadening of the two modes,where the anisotropy of phonon dispersion curves along Γ-K and Γ-M is also considered.The photoluminescence spectra confirm the formation of small domain size of 1L MoS_2 nanocrystallites in the ion-implanted 1L MoS_2.This study provides not only an approach to quickly probe phonon dispersion trends of 2D materials away from Γ by the Raman scattering of the corresponding NCs,but also a reference to completely understand the confinement effect of different modes in various nanomaterials. The fundamental momentum conservation requirement q ~ 0 for the Raman process is relaxed in the nanocrystallites (NCs), and phonons away from the Brillouin-zone center will be involved in the Raman scattering, which is well-known as the phonon confinement effect in NCs . This usually gives a downshift and asymmetric broadening of the Raman peak in various NCs. Recently, the A’_1 mode of 1L MoS2 NCs is found to exhibit a blue shift and asymmetric broadening toward the high-frequency side [Chem. Soc. Rev . 44 (2015) 2757 and Phys. Rev. B91 (2015) 195411]. In this work, we carefully check this issue by studying Raman spectra of 1L MoS2 NCs prepared by the ion implantation technique in a wide range of ion-implanted dosage The same confinement coefficient is used for both E ’and A’_1 modes in 1L MoS_2 NCs since the phonon uncertainty in an NC is mainly determined by its domain size. The asymmetrical broadening near the A’_1 and E’ modes is attributed to the appearance of defect-activated phonons at the zon e edge and the intrinsic asymmetrical broadening of the two modes, where the anisotropy of phonon dispersion curves along Γ-K and Γ-M is also considered. photoluminescence spectra confirm the formation of small domain size of 1L MoS_2 nanocrystallites in the ion-implanted 1L MoS_2.This study provides not only an approach to quickly probe phonon dispersion trends of 2D materials away from Γ by the Raman scattering of the corresponding NCs, but also a reference to completely understand the confinement effect of different modes in various nanomaterials.