[pam-users] isopropyl nitrite photolysis in OFRs: an alternative high-NO OH source

[pam-users]

For OFR user looking to explore application of a high-NO OH source that 
is complementary to OFR254/185-iN2O, you may be interested in our AMT 
manuscript that was recently published:

Lambe, A. T., Krechmer, J. E., Peng, Z., Casar, J., Carrasquillo, A. J., 
Raff, J. D., Jimenez, J. L., and Worsnop, D. R.: HO_x and NO_x 
production in oxidation flow reactors via photolysis of isopropyl 
nitrite, isopropyl nitrite-d_7 , and 1,3-propyl dinitrite at λ = 254, 
350, and 369 nm, /Atmos. Meas. Tech/., 12, 299-311, 
https://doi.org/10.5194/amt-12-299-2019, 2019. Abstract 
<https://www.atmos-meas-tech.net/12/299/2019/amt-12-299-2019.html>, PDF 
<https://www.atmos-meas-tech.net/12/299/2019/amt-12-299-2019.pdf>and 
Supplement 
<https://www.atmos-meas-tech.net/12/299/2019/amt-12-299-2019-supplement.pdf>. 


Some additional comments and recommendations:

1. To examine high-NO photochemistry in OFRs, start with OFR254/185-iN2O 
because it is easier to implement, especially when beginning with 
OFR254/OFR185 as is the case for most OFR users. Refer to Lambe et al., 
AMT, 2017 and Peng et al., ACS Earth & Space Chem, 2018, for the initial 
characterization of OFR254/185-iN2O.

2. If your application of OFR254/185-iN2O generates conditions that may 
be influenced by O3, NO3 , and/or 254 nm photolysis, consider testing 
isopropyl nitrite photolysis as an alternative radical precursor.  
Optimal implementation of this method involves  introduction of  ~10 ppm 
of isopropyl nitrite (iPrONO) into the OFR and substitution of 254 nm UV 
lights with blacklights. This will generate ~0.5 days' OH exposure under 
high-NO conditions, with minimal O3/NO3. iPrONO is commercially available.

3. If OFR369-i(iPrONO) works adequately for your application, consider 
learning how to synthesize perdeuterated isopropyl nitrite (iPrONO-d7) 
using the methods described in this work. We found that 
OFR369-i(iPrONO-d7) achieved nearly 1 day OH exposure under high-NO 
conditions.

4. We found that NOx generated from iPrONO photolysis interfered with 
SO2 analyzer measurements, and we found that iPrONO interfered with NOx 
analyzer measurements. The OHexp and NO2 estimation equations that were 
developed in this paper will be incorporated into a future version of 
PAMcontrols, but if you are interested to experimentally characterize 
OHexp, NO & NO2, keep these potential limitations in mind.

5. If you are able to build on this work by synthesizing novel alkyl 
nitrites that perform better than iPrONO-d7, please give a presentation 
on your work at a future PAM/OFR users meeting.

Best regards,

Andy et al.

-- 
Andrew Lambe
Principal Scientist
Center for Aerosol and Cloud Chemistry
Aerodyne Research, Inc.
45 Manning Rd., Billerica, MA, 01821
+1-978-663-9500 x 209

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