ROOOH: a missing piece of the puzzle for OH measurements in low-NO environments?

Fittschen, Christa; Al Ajami, Mohamad; Batut, Sebastien; Ferracci, Valerio; Archer-Nicholls, Scott; Archibald, Alexander T.; Schoemaecker, Coralie

doi:https://doi.org/10.5194/acp-19-349-2019

Articles | Volume 19, issue 1

https://doi.org/10.5194/acp-19-349-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/acp-19-349-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 19, issue 1

Research article

|

10 Jan 2019

Research article |

| 10 Jan 2019

ROOOH: a missing piece of the puzzle for OH measurements in low-NO environments?

Christa Fittschen, Mohamad Al Ajami, Sebastien Batut, Valerio Ferracci, Scott Archer-Nicholls, Alexander T. Archibald, and Coralie Schoemaecker

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Final revised paper (published on 10 Jan 2019)
Supplement to the final revised paper
Preprint (discussion started on 05 Jun 2018)
Supplement to the preprint

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

SC1: 'Questions and comments on "ROOOH: the Missing Piece of the Puzzle for OH measurements in low NO Environments"', Frank Winiberg, 26 Jun 2018
- AC1: 'Answer to Fred Winiberg's questions', Christa Fittschen, 06 Jul 2018
RC1: 'Review', Hartwig Harder, 16 Jul 2018
- AC2: 'Answer to Hartwig Harder's comments', Christa Fittschen, 03 Sep 2018
RC2: 'Anonymous Referee', Anonymous Referee #2, 08 Aug 2018
- AC3: 'Answer to anonymous referee', Christa Fittschen, 03 Sep 2018

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

AR by Christa Fittschen on behalf of the Authors (03 Sep 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (12 Sep 2018) by Frank Keutsch

RR by Anonymous Referee #2 (23 Sep 2018)

RR by Hartwig Harder (18 Nov 2018)

Suggestions for revision or reasons for rejection

The author addressed the questions raised in the first review but one, the mechanism of ROOOH decomposing into OH.

The original claim of the paper that ROOOH is the missing source of interference got toned down. Still I don't see how the night time increase of the interference reported by Mallik et al or Novelli et al can be explained by night time formation of ROOOH from RO2+OH. My last remaining minor issue is to ask the authors to note this contradicting published result in their work.

By all my reservation that ROOOH is a major contributor to the LIF interference reported mainly by us and Bill Brune's group, the chemistry of RO2+OH and the product ROOOH is very interesting and therefore I recommend publication.

To address the remaining open question of the mechanism requires additional work that may be beyond the scope of this study. I still would like to encourage the authors to look into :

- to change the residence time after passing the pinhole to derive from the temporal behavior of OH loss and production terms inside as shown by Novelli et al.

- change the diameter and length of the inlet behind the pinhole to investigate if wall contact is important. If so, does the choice of material or coating at the wall makes a difference. For our LIF we tested and can exclude the walls being involved as we used Macrolon tm (plastic), stainless steel, aluminum anodized & not anodized and none changed the result.

- does the use of a glas capillary change the result as the gradual pressure drop would reduce the effect of a shock wave, indicating if the cluster formation is of any importance. For us I can neglect this.

- does a flat plate or just a conical beam skimmer vs a Laval nozzle as pin hole affect the outcome as the flow though a free expansion of the jet behind a flat plate still generates an eddy whereas this is surpassed in a Laval nozzle.

- does the use of a single beam vs multi pass cell makes a difference ?

Cheers
Hartwig

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ED: Publish subject to minor revisions (review by editor) (22 Nov 2018) by Frank Keutsch

AR by Christa Fittschen on behalf of the Authors (23 Nov 2018) Author's response Manuscript

ED: Publish subject to minor revisions (review by editor) (18 Dec 2018) by Frank Keutsch

Dear authors,

thank you for your detailed responses to all reviewer comments. The work highlights the importance of an overlooked class of molecules, ROOOH and their potential source of interference OH in instrumentation. The interesting and important manuscript also highlights that more work on studying ROOOH is very important. The manuscript is ready for publication after consideration of the following minor comments:

1. Abstract. line 13 "interference" line 20 "background OH": It would be useful to make clear that you mean the "interference OH" not "background atmospheric OH", unless I am mistaken. As "background OH" is used throughout the manuscript, it would be helpful to clearly define it here, so readers will not get confused.

2. p.3 line 4 For the first use of C3F6 as scrubber of OH in ambient OH LIF measurements trying to quantify interferences the reference should be Dubey, M. K., Hanisco, T. F., Wennberg, P. O., and Anderson, J. G.: Monitoring potential photochemical interference in laser-induced fluorescence measurements of atmospheric OH, Geophys. Res. Lett., 23, 3215–3218, 1996. A different OH LIF setup but the first, to my knowledge, to demonstrate this concept for ambient OH-LIF.

3. p.3 Line 21. I suggest inserting “with different FAGE systems” between “However” and “Rickly”

4. p4 Line 14. I suggest inserting “of the reaction of RO2 +OH” between “reaction product” and “will also be” otherwise it sounds like it will be the overall major product, i.e., not ROOH or others

5. p.8 line 6. Should the mixing in of gas from outside the photolysis beam be included in this list?

6 p.18 line 6. I suggest that, if I understand correctly, these environments are daylight and not nighttime environments.

Just a comment. For 1,2-ISOPOOH and 4,3-ISOPOOH the OH reaction rate constants are about 7.5x10^-11 and 1.2x10^-10 cm^-3 s.

Please do not hesitate to contact me if you have additional questions.

Best Regards,

Frank Keutsch

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AR by Christa Fittschen on behalf of the Authors (20 Dec 2018) Author's response

ED: Publish as is (21 Dec 2018) by Frank Keutsch

AR by Christa Fittschen on behalf of the Authors (21 Dec 2018) Manuscript

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Short summary

Concentrations of OH, the main oxidant in the atmosphere, were measured in biogenic environments up to a factor of 10 higher than predicted by models. This was interpreted as a major lack in our understanding of biogenic volatile organic compound chemistry. But interferences of unknown origin have also been discovered, and we present experimental and modelling evidence that the interference might be due to the unexpected decomposition of a new class of molecule, ROOOH, in the FAGE instruments.