Absolute Absorption Cross-Section of the Ã←
, Weijun Zhang 2,3, Laure Pillier 1, Coralie Schoemaecker 1 and Christa Fittschen 1,*Round 1
Reviewer 1 Report
comments are minor. I do not need to see the paper again.sd
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Reviewer 2 Report
This manuscript describes measurements of the absolute absorption cross section of ethyl peroxy radicals in the mid-infrared, and the rate constant for their reaction with HO2 radicals. The experiments used a previously well-characterized double-beam cavity ring down system that has been used for a number of studies in the past. The data are of a very high quality.
This is a very good short paper. Despite its brevity it contains a lot of information, and a thorough description of the methods and analysis.
I recommend publication after consideration of a few relatively minor points below. The grammar is generally very good. The figures are appropriate for the length of the article.
I thought maybe a Table showing the initial starting conditions might be useful, but also note that they are available on request.
On Line 296 it says that a concentration of 1.2E14 Cl atoms are used (determined by HO2 absorption). However, from an examination of Figure 5, the concentrations of [C2H5O2] + [HO2] do not add up to this number in the upper two fits. In fact, the lower pair (with the lowest C2H5O2 cross section) seems to give the best fit. Was this taken into consideration in determining the final results?
Around lines 297-300, the concentrations of CH3OH and C2H6 don’t reproduce the ratios of HO2/C2H5O2 provided. For example, the lowest [CH3OH] is 3x higher than the highest [C2H6], so hard to get a ratio of 0.2, considering that the rate constants with chlorine are essentially equal. Should the [C2H6[ have an exponent of 10^15? (see also comment above about the need for a Table of conditions)
In Table 2, the branching ratio for reaction 1 is ~30% radicals, ~70% molecular. These values, from Noell et al., have not been validated, and contradict the older chamber measurements. Is the fitting sensitive to this number at all?
Line 380. Please check, I think 7496 should be 7596?
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