Review of 'Atomically thin MoS2: A new direct-gap semiconductor'

The article is focused on investigating the electronic properties of ultrathin crystals of molybdenum disulfide (MoS2) by optical spectroscopy. The article is well-structured and presents a systematic study of the evolution of the optical properties and electronic structure of ultrathin crystals of MoS2 as a function of thickness. The article provides a detailed explanation of the transition-metal dichalcogenide semiconductor MoS2 and its properties. The experimental techniques used to characterize the samples are also clearly explained.

The article is well-written and the information is presented in a concise and organized manner. However, there are a few revisions that could improve the article. Firstly, the abstract could be more detailed and include more information about the results obtained from the study. Secondly, the article could benefit from a discussion section where the authors interpret the results obtained and compare them to previous studies.

The strength of the article lies in its comprehensive study of the evolution of the optical properties and electronic structure of ultrathin crystals of MoS2 as a function of thickness. The experimental techniques used to characterize the samples are also appropriate and clearly explained. However, the article lacks a discussion section where the results obtained are interpreted and compared to previous studies.

In conclusion, the article is well-written and presents a systematic study of the evolution of the optical properties and electronic structure of ultrathin crystals of MoS2 as a function of thickness. The authors have used appropriate experimental techniques to characterize the samples. However, the article could benefit from a more detailed abstract and a discussion section to interpret the results obtained and compare them to previous studies.