Excitons in Carbonic Nanostructures
Round 1
Reviewer 1 Report
In this review, the peculiar spectral properties of carbon materials in the nanoscale domain are discussed. In particular, the similarities in their photophysical behavior regardless of their size, structure and composition and their bright emission are elucidated applying the molecular excitons theory, already used to describe the properties of organic dyes aggregates and crystals. Such theory considers carbonic nanostructures as H-aggregate based excitonic systems capable of efficient energy conversion and photon emission and, if further complemented, according to the author, it could provide a general framework to advance the understanding of the quantum phenomena behind the behavior of carbon nanomaterials and to tailor their properties and structure for desired applications.
The review is clearly and elegantly written. The analysis of the photophysics of carbon nanomaterials in light of the molecular exciton theory appears well argumented and rigorously debated. I recommend publication after a text revision, as the English grammar and style require some (minor) improvement.
Author Response
I thank the Reviewer for reading and evaluating my paper. The paper was carefully checked, the style and spelling errors were found and corrected
Reviewer 2 Report
In this review study, the author described the photophysical behavior of carbon-based dots/nanoparticles using a well-established physical theory of molecular excitons. In brief, the article is well written and organized, therefore, it can be considered for publication after a minor revision.
1) It will be interesting if the author also briefly discuss the case of excitation-independent emission of carbon dots.
2) The manuscript can be improved by addition of highly relevant studies such as:
a) Common origin of green luminescence in carbon nanodots and graphene quantum dots, ACS Nano 2014, 8, 2541-2547.
b) Doped carbon dots for sensing and bioimaging applications: A minireview, Nanomaterials 2018, 8, 342.
Author Response
I am grateful to the Reviewer for reading and evaluating my paper.
Let me respond point-by-point to Reviewer's comments
1) It will be interesting if the author also briefly discuss the case of excitation-independent emission of carbon dots.
The cases of excitation-independent emission of C-dots were cited in Section 3.4. However, the key point of discussion was on the origin of heterogeneity leading to excitation dependence of emission spectra.
2) The manuscript can be improved by addition of highly relevant studies such as:
a) Common origin of green luminescence in carbon nanodots and graphene quantum dots, ACS Nano 2014, 8, 2541-2547.
This paper was cited already twice as ref. [69].
In Section 2.1 I wrote:
"Fluorescent carbon dots (C-dots) are the most versatile but less defined and less characterized members in the family of nanocarbon materials. Meantime they share similar properties with G-dots and GO-dots [69] that are discussed above."
The second cytation was in Conclusions. However, analysing this comment I read this paper again and extended the discussion. Now this part is formulated in the following words:
"Meantime, as it was often noted, these nanoscale emitters demonstrate surprising general regularities. The similarities of spectroscopic behavior between G-dots, GO-dots and C-dots [11,12,69] allow us to believe that they have a common origin. We observe that passivation and doping by different heteroatoms change dramatically the spectroscopic properties of different carbon nanostructures shifting their emission strongly to the red [133,134]. It becomes the actual task to understand how there changes the of energy of excitonic states. The common origin between C-dots and GO-dots demonstrating green emission was attributed to surface states with the participation of carboxyl and carbonyl groups [69]. Attachment of heteroatoms may change dramatically configuration and energetics at these sites as they serve as exciton traps. Many routes can be followed to optimize their properties if we start to know the photophysical mechanisms in the background of these effects."
b) Doped carbon dots for sensing and bioimaging applications: A minireview, Nanomaterials 2018, 8, 342.
I read this paper and found that it is still outside the scope of my Review. It is a minireview addressing synthesis and application of C-dots, whereas my aim was to focus on the mechanisms of fluorescence.
Round 2
Reviewer 1 Report
The review is now suitable for publication.
Reviewer 2 Report
No more comments, this work can be considered for publication
