Single-Particle Analysis of Atmospheric Aerosols: Applications of Raman Spectroscopy
and Charuvila T. Aravindakumar 1,4,5,*
Round 1
Reviewer 1 Report
The manuscript offers a good overview of the importance Raman spectroscopy as a powerful tool in studying atmospheric aerosols, and it should be published after considering input and comments from various reviewers.
Main comment:
Since this is a review article, there is nothing wrong with it being long. As written, it contains a lot of statements in form of very short sentences, with proper citations. However, for a non-expert reader these statements might lose their meaning, unless if the reader stops at each time to check out the cited articles. We recommend the authors to revise the writing, wherever it is possible, by expanding those statements, for the sake of giving the reader a clear context or background reasons.
Here below we highlight some other minor comments that might help the authors to improve the quality of the manuscript:
All figures: please, show proper citation and give credit if they are taken from published articles
P2: add a short sentence to define PM2.5 and state why they are so important in atmospheric aerosol field
P2: please, define offline & online techniques for a general reader
P4: in line 128, clarify elastic vs inelastic in terms of change in energy for incident and scattered photons.
P5: please, define deliquescence for the general reader
P6: provide the Raman shift for the mentioned G band
P7: DEPh is a safe chemical simulant used in laboratory experiments in a place of the highly lethal VX agent
P9: to highlight the importance of Raman spectroscopy, there are more recent studies of liquid-liquid and solid-liquid phase separation in optically trapped droplets (without shape deformation resulting from particle resting on the substrate.)
p.10: polyethylene abbreviation is (PE), PP is for polypropylene
p10: provide G and D bands Raman shift frequencies
P.12: the issue of a weak Raman signal, resulting in longer acquisition time could be brought up earlier, at the beginning of the paper (background section). Provide general advantages and disadvantages of Raman spectroscopy of aerosol particles, depending on the conditions and goals of the measurement. Talk about accuracy, speed, cost, instrument bulkiness, sample preparation, etc. for a non expert reader.
Author Response
Please find our response attached herewith
Author Response File: 
Author Response.pdf
Reviewer 2 Report
In this paper, the authors reviewed the single particle analysis of atmospheric aerosols by Raman spectroscopy.
The paper is well written. The methods used and the results obtained are reasonably well documented. In the third part, the authors describe laboratory tests, including details of hygroscopicity, INP, organic aerosol, mineral dust and LLPS. Later sections (4, 5, and 6) focused on different type of Raman techniques (MRS, SERS and SRS). They give a very good picture of the advantages and disadvantages of the method. I therefore recommend the manuscript for publication in the journal Atmosphere.
The authors, however, should consider the following questions and recommendations when preparing the final draft. (In specific cases I refer to the page and line numbers of the draft I received.)
Th authors mentioned in the abbreviations the PIXE technique. However in the text it was not found. So please apply some references about this technique:
https://doi.org/10.1016/S1352-2310(00)00410-6
https://doi.org/10.1016/j.nimb.2010.02.090
https://doi.org/10.1016/j.nimb.2011.02.057
There is some typing typo. Please read carefully and correct. I will highlight just a few of them here.
The word "figure" and „table” are in lower case in the text. In addition, these words are followed by dot. This should not be used. Please correct them.
There is a colon after the title of each section. This is not necessary, please correct them.
Page 8, Line 281: The authors write N205. Please correct the formula and check all.
Page 9, Line 295: The authors write Table 78 at the beginning of the row. I do not think it should be there.
Author Response
Please find our response attached herewith
Author Response File: Author Response.pdf
Reviewer 3 Report
This study reviews the merits and demerits of various offline and online aerosol research techniques. This review focuses on the application, edge, and measurement of Raman spectroscopy. This review suggests that surface-enhanced Raman spectroscopy has an advantage over conventional micro Raman spectroscopy. Laboratory simulation and field observation of aerosols by Raman spectroscopy are further discussed. Although this review elaborates the applications of Raman spectroscopy in the single particle analysis, some problems listed below need to be addressed before the manuscript could be published.
1. Section 3.2: The authors showed characteristic peaks of biogenic isoprene. How about anthropogenic VOCs such as ethene?
2. L281: The format of N2O5 is wrong.
3. Figure 1 is not explained in the text.
4. L157: “figure.2” is nonstandard. It should be “Figure 2”. Others also need to be modified.
5. L295: I confused about Table 78.
6. L302-303: The black carbon here is not really a single black carbon particle. Thus, this phenomenon may not be accurate enough only depending on this study. However, another study finds the redistribution of single black carbon particles in LLPS aerosols using electron microscopy （e.g., Communications Earth & Environment, 3(1), 128. https://doi.org/10.1038/s43247-022-00462-1） The authors can further prove this phenomenon based on the above study.
Author Response
Please find our response attached herewith
Author Response File: Author Response.pdf
