Annual-Report-2019

EXPERIMENTAL MEASUREMENTS OF
ATMOSPHERIC CHEMICAL REACTIONS
Earth, Ecology & Environment Sciences 2019
72
Dr Max McGillen
From:University of Bristol - UK
In residence at: The Institute of Combustion
Aerothermal Reactivity and Environment
(ICARE) - Orléans
Nationality: British
Dates:
LE STUDIUM Research Fellow
ARD 2020 PIVOTS Programme
September 2018 to December 2018
April 2019 to September 2019
Dr Max McGillen has worked in several laboratories
in the UK, and has earned international
experience in the USA, Ireland and France.
He has worked in a variety of areas including
laboratory measurements, field measurements
and structure activity relationships. This has
resulted in a broad understanding of atmospheric
chemistry. Max has been the recipient of an
ESF exchange grant, a Marie Skłodowska Curie
Research Fellowship, and is now enjoying his
status as a Le Studium Fellow. He is also an active
member of an international expert panel on the
evaluation of structure-activity relationships, and
is currently leading their efforts to compile and
review an extensive atmospheric kinetic database;
Dr Abdelwahid Mellouki
Host scientist
Dr Abdelwahid Mellouki’s undergraduate and
graduate studies were conducted in the Universities
of Tours, Orleans and Paris 7 (France). He spent
two years as a Research Associate at the National
Oceanic and Atmospheric Administration’s
Aeronomy Laboratory (Boulder-Colorado). His
main research fields are Chemical Kinetics,
Atmospheric Chemistry, Air Pollution and Climate
change. He joined the CNRS in 1992, where he is
currently a Research Director at ICARE in Orléans
(France), leading the Atmospheric Reactivity Group.
He has been nominated National Distinguished
Professor at Shandong University (China) and
Guest Professor at the Chinese Academy of
Science (CAS/ RCEES-Beijing) and Fudan University
(Shanghai). His research over focus on many
aspects of atmospheric chemistry, including the
study of the atmospheric oxidation mechanisms
of anthropogenic and biogenic carbon-containing
species and halogen chemistry. He is author or
coauthor of over 200 scientific publications/chapters
related to atmospheric chemistry.
The goal of this project is to obtain accurate and precise data on the
rates and products associated with chemical reactions occurring in the
atmosphere, using a wide variety of measurement techniques available
at ICARE. Some of these measurements are challenging and the fellow
will be required to utilize his experience to try to address long-standing
uncertainties within atmospheric chemistry. He will also helping to develop
experimental protocols and techniques at the host laboratory.
Achievements so far: The fellow has been focusing on the reaction of
sulphur dioxide with the OH radical. This is a very important reaction in
atmosphere, since it leads to the formation of sulphuric acid, which is
of crucial importance to aerosol formation, and therefore has a major
effect in terms of air pollution and climate change. However, there remain
some key uncertainties in this reaction rate, primarily related to the
effect of pressure on this reaction. To begin with, a thorough survey of
the literature regarding this reaction was performed, and the gaps in the
knowledge were assessed. Accordingly the fellow has conducted a series of
careful measurements in the presence of a variety of bath gases (helium,
nitrogen and argon) using the pulsed laser photolysis–laser induced
fluorescence (PLP-LIF) technique. The maximum pressure available to
the PLP-LIF technique is ~400 Torr (below atmospheric pressure), and
therefore to complement this technique, a series of simulation chamber
measurements have been made in the presence of nitrogen, oxygen, argon
and air at 760 Torr. By measuring this reaction using different techniques
over a wide range of conditions, we have made definitive progress regarding
understanding the pressure dependence of this reaction. This allows us to
compare with previous measurements, and to determine, which, if any, are
accurate. It is expected that this work will result in a publication that will
be of interest to the atmospheric chemical community. The fellow has also
taken the responsibility of instructing a PhD student, Ms. Hajar Elothmani,
in atmospheric chemistry and the techniques involved in making accurate
gas-phase kinetic measurements. Dr McGillen has also supervised a
project of a post-doctoral appointee, Dr Soukaina Foulal, which investigates
the impact of jet-fuel emissions upon air quality. This has led to an ongoing
collaboration with Dr Bernard Aumont at the Laboratoire Interuniversitaire
des Systèmes Atmosphériques in Paris, which will also be worthy of
publication in the future.
Dr McGillen was also able to provide his experience and expertise in a
groundbreaking field measurement campaign in the Atlas Mountains in
autumn 2019, where the ICARE team led an international effort in making
some of the first detailed atmospheric chemical measurements in North
Africa.