1 AN INTERVIEW FOR
Partners In Research blog!
(Anne Ramsay & Christine Park,
Communications Team, Partners In Research,
519-433-7866 x 23)
by
Raymond E. March, PhD, DSc, D(hc), FCIC
Department of Chemistry, Trent University,
1600 West Bank Drive, Peterborough, ON, K9J 7B8
Tel: 705 748 1011 (7361)
E-mail: [email protected]; [email protected]
Friday, January 02, 2015
How did you come to be a part of Philae project?
The Rosetta spacecraft has been flying through space for ten and a half years. Its
departure from Earth was postponed for a little more than one year due to rocket failure.
Preparation of the initial proposals for some twenty experiments concerning examination of a
comet, and construction of instrumentation (plus, for Ptolemy, a duplicate instrument that
remained in the laboratory) added some 5-6 years so that the Philae project started prior to 1997.
Thus, it is necessary to go even further back in time to answer the leading question above.
As a new (and young) Assistant Professor in a new (and impecunious) university, I had to
decide upon a field for future research within the general area of Physical Chemistry, as my
employer Trent University in Peterborough, Ontario, had hired me on the basis of my University
of Toronto PhD degree in Physical Chemistry. The need for a decision was urgent because, in
1969, the deadline for applying for a sabbatical leave in 1972-73 was almost upon me. I had
Partners in Research Interview, REM2 2 some experience of upper atmospheric chemistry from my time at McGill University and so I
had tried to study the highly exothermic reaction
𝑵. + 𝑵𝑶. = 𝑵!𝟐 (𝑿𝟏 Σ ) + 𝑶 (1) where † represents vibrational energy and X1Σ represents the ground electronic state of N2.
Briefly, molecular nitrogen is represented normally with a triple bond between the two nitrogen
atoms, hence reaction (1) in which molecular nitrogen is formed, is highly exothermic.
However, immediately after formation of the homonuclear diatomic molecule N2, the reaction
exothermicity appears as vibrational excitation of the newly-formed bonds; it is only after the
exothermicity has degraded from vibrational energy to translational energy that heat is apparent.
Because N2 is a homonuclear diatomic molecule it does not emit infra-red photons, as does the
heteronuclear diatomic CO†, for example, and so vibrational excitation in N2 must degrade
slowly to translational or kinetic energy.
I wanted to investigate the distribution of vibrational levels excited in nascent N2 and so I
decided to ionize the nascent nitrogen molecules by electron impact to the B2Σ electronicallyexcited state of N2+. Subsequent emission of blue light in the region of 3915 Å, known as the
first negative system of N2+ that is, B2Σ → Σ 2Σ, would show the relative intensities (or
vibrational populations) of the nascent N!! (X! Σ ). Alas, the reaction of vibrationally-excited N2+
in the B2Σ electronically-excited state with many background neutral species can proceed rapidly
due to an ion-induced dipole created in the neutral species when there is no activation energy
barrier. Thus the vibrational distribution was perturbed by ion/molecule reactions. At that stage,
I decided to study the chemistry of gaseous ions using the technique of mass spectrometry.
Professor Jean Durup of l’Université Paris Sud at Orsay, France, agreed that I could visit
his laboratory and carry out research in gaseous ion chemistry. Charged species or ions in the
gas phase are tractable in that the movement pf ions can be controlled by magnetic and electric
fields using either direct current (DC) or radio-frequency (RF) potentials. The time spent in
Orsay was very fruitful. Towards the end of my stay, I went to the University of Kent in
Canterbury, UK. I had seen an article in Chemistry in Britain concerning the performance of a
quadrupole ion trap (QIT) or QUISTOR (QUadrupole Ion STORe); it was written by John F.J.
Todd whom I had known as an undergraduate at the University of Leeds, UK. In 1973, I spent 3
months in the laboratory of Professor Todd; this experience was the beginning of our
collaboration both in research and in the authoring/editing of books, that remains active today,
some forty tears on.
I imagined the QIT as a test-tube for confining gaseous ions but in the absence of solvent.
Consider adding 2 mL of dilute sulphuric acid to the same volume of barium chloride solution in
a test-tube. The ion/ion reaction
𝑆𝑂!!! + 𝐵𝑎!! = 𝐵𝑎𝑆𝑂! ↓ (2)
Partners in Research Interview, REM2 3 occurs immediately as shown by the instantaneous appearance of barium sulphate precipitate.
Could the QIT be used for studying ion/ion neutralization reactions as well as ion/molecule
reactions?
A cross-section of the QIT is shown in Figure 1(a) together with a schematic diagram,
Figure 1(b).
(a)
(b)
Before leaving the University of Kent, Todd and I agreed that the ‘standard’ quadrupole ion trap
(QIT) would have the inner radius of the ring electrode, r0, as shown in Figure 1(b), set at 1 cm;
all other ion QITs would be compared to this standard QIT. This single value was sufficient to
determine the magnitude and spacing of all three electrodes because r0 and the separation of the
two end-cap electrodes, 2z0, are related as
𝑟!! = 2𝑧!!
(2).
Upon returning to Canada in 1973, following the completion of my sabbatical leave, I
decided to construct a quadrupole ion trap (QIT) and to build the various electronic units that I
would need to operate the instrument, to construct a glass vacuum system for handling gases at
low pressure, and to purchase an oscilloscope. The rationale for this decision was that I found
the QIT as ‘an electronic test-tube’ to be fascinating and, as it was not possible to purchase such
an instrument, I would not face any competition from commercial instruments in older
universities. I would build a QIT for trapping gaseous ions; Todd and I offered the following
definition of a trapped ion: “an ion is ‘trapped’ when its residence time within a defined spatial
region exceeds that had the motion of the ion not been impeded in some way”1. What an
adventure to impede ion motion and prolong the duration of observation! Slowly the parts came
together so that by 1976 we were able to publish our first paper2 on work carried out at Trent
University in Canada; the authors of this paper were Ron Bonner, a post-Doctoral fellow with
1
R.E. March and J.F.J. Todd (Eds.) Practical Aspects of Trapped Ion Mass Spectrometry: Theory and
Instrumentation, Vol. 4. Boca Raton, FL: CRC Press, 2010, p. 7.
2
R.F. Bonner, R.E. March and J. Durup. "The effect of charge exchange reactions on the motion of ions in threedimensional quadrupole electric fields." Int. J. Mass Spectrom. Ion Phys. 22 (1976) 17-34.
Partners in Research Interview, REM2 4 whom I had worked when he was a graduate student in Todd’s group at the University of Kent,
UK, myself and Professeur Jean Durup who had been my host during my sabbatical work at
Orsay, France. Little did we know, or even suspect, that collisional focusing of ions in
quadrupole devices would become so important.
In 1983, the first commercial version of a QIT, the ITD™ (Ion Trap Detector combined
with a gas chromatograph and bench-top computer) was announced by Finnigan Co. A
commercial QIT translated to many users, probably graduate students and technicians, struggling
to use new technology ion confinement theory that were unknown to their managers; thus, a
textbook was needed. Our first text,3 a guide for new QIT users, was published in 1989 and
coincided with the award of the Nobel Prize in Physics to Wolfgang Paul, the inventor of the
QIT and quadrupole mass filter.
Research continued into the 1990s with the publication of several papers and three
volumes.4 In 1997, I presented an Invited Lecture5 at the 14th International Mass Spectrometry
Conference in Tampere, Finland, in August 1997. This was a memorable conference for two
reasons. First, I met a group of scientists from the Open University, UK, who presented a
lecture6 on a miniature QIT for the determination of stable isotope ratios on a comet and, second,
unable to get home on August 30th after the conference, I woke in a hotel in Lyon, France, on
Sunday morning, August 31st, 1997, to learn that Princess Diana had died earlier that morning in
a car crash in Paris. I recall chatting with the Open University group and inquired why they had
described their QIT as ‘miniature’ which was not terrible descriptive particularly when miniature
ion traps, with r0 ≈ 0.45 mm had been discussed in the literature. Later, Todd and I
recommended that for a miniature ion trap the ring or barrel electrode radius should be <10 mm;
when the radius is <1 mm, such ion traps should be described as submillimeter or micro ion
traps. The ring radius of the Open University QIT7 was 8 mm.
It was not until Tuesday, March 2, 2004, that the Ariane-5 rocket carrying the Rosetta
“comet chaser” was launched at Kourou in French Guyana; on board the Rosetta spacecraft was
3
R.E. March, R.J. Hughes and J.F.J. Todd. Quadrupole Storage Mass Spectrometry. Chemical Analysis Series, vol.
102. New York: John Wiley, 1989.
4
R.E. March and J.F.J. Todd (Eds.) Practical Aspects of Ion Trap Mass Spectrometry: vols. 1-3. Boca Raton, FL:
CRC Press, 1995. 5
R.E. March. "Advances in quadrupole ion trap mass spectrometry: instrument development and applications."
Invited lecture, 14th Int. Mass Spectrometry Conference, Tampere, Finland, Aug. 25-29, 1997 Adv. Mass Spectrom.
14 (1998) 241-278, Elsevier, Amsterdam. 6
Barber, SJ, Morse AD, Wright IP, Kent BJ, Waktham NR, Todd JFJ, Pillinger CT. Development of a miniature
quadrupole ion trap mass spectrometer for the determination of stable isotope ratios. In Advances in Mass
Spectrometry, Oral B03 TUOR06, vol. 14, Karjalainen EJ, Hesso AE, Jalonen JE, Karjalainen UP (eds.) Elsevier
Science Publishers: Amsterdam, 1998. 7
Barber SJ. Development of a miniature quadrupole ion trap mass spectrometer for the determination of stable
isotope ratios: application to a space-flight opportunity, PhD thesis, The Open University, UK, 1998.
Partners in Research Interview, REM2 5 the QIT of the Open University. Due to an earlier launch failure for a priority payload, the
Rosetta launch had been delayed so much that the window of opportunity for accessing the initial
selected comet was closed. A new target comet was chosen; this target was named 67P C-G
after Churyumov-Gerasimenko. The excitement of the launch success faded as the spacecraft
settled into its decade-long journey and the scientific package was ‘put to sleep’. Todd and I
were working on the second edition of our 19893 text in 2005 when we decided to ask the Open
University group if we could include in our second edition a ‘Chapter 9’ on the Rosetta mission
to characterize a comet. Agreement was reached speedily, we set to work on the material, and
the second edition was published8 yet, to our knowledge, Chapter 9 attracted little interest.
It was not until 30th January, 2014, that world interest was stirred when Rosetta answered
the wake-up call. The electronic instruments in the spacecraft were subsequently warmed from
the intense cold of space and, to the delight of all involved, a mass spectrum of ambient gases
was beamed back to Darmstadt, the control centre for the European Space Agency (ESA).
Immediately, Todd and I requested of John Wiley & Sons that they make readily available the
complete text of Chapter 9 so that students of all ages could read of the Rosetta Project and
become aware of the twenty proposed experiments for the Project. To access Chapter 9 of
Quadrupole Ion Trap Mass Spectrometry by RE March & JFJ Todd either use
http://www.spectroscopynow.com/details/ezine/143c4d0c63a/Rosetta-Heads-to-Comet-forSome-Serious-GCMS_-Read-Free-Chapter-from-Quadrupole-.html or go to www.trentu.ca
then click on the top entry 'Trent University‘. Find 'About Trent' (near the top right hand
corner), then scroll down to click on 'News and Events'. Locate 'Latest Headlines' near the centre
of the screen. Scroll down to click on 'Read more news'; near the screen centre, locate 'Earlier
News Reports' then enter a search for 'Rosetta'. You will be presented with two news items, the
first for Tuesday, November 11, 2014 and the second for January 30, 2014. Go to the latter and
click on 'Trent link to the Rosetta 'Comet Chaser' Mission. At the foot of the page you will see
'The chapter can be found here'. Click on 'here' and you will be transported to the 'Spectroscopy
Now' page of John Wiley & Sons. Click on 'For access to free chapter' and the entire chapter,
published in 2005, will appear on your screen.
What was your role in this project? The main roles for Todd and me have been to check every aspect of the information
given to us concerning the Ptolemy experiment, that is, measurement of the isotope ratios for
hydrogen, carbon, nitrogen and oxygen; to prepare material for publication as Chapter 9; to make
available by all possible means, including this work, the objectives of the Rosetta Project and the
details of all twenty experiments, eleven from the Orbiter and nine from Philae, the Lander that
was deposited not once but three times on the surface of the comet 67P. At this time of writing,
8
R.E. March and J.F.J. Todd. Quadrupole Ion Trap Mass Spectrometry, Second edition of Quadrupole Storage
Mass Spectrometry. Chemical Analysis Series, vol. 165. John Wiley & Sons, Inc. Hoboken, New Jersey, 2005.
Partners in Research Interview, REM2 6 the Rosetta Project has been an enormous success despite the distance from Earth of comet 67P;
communication from Darmstadt, Germany, to 67P takes 27 minutes for transmission one way.
As radio waves travel at the speed of light, 186,000 miles/second (or, for a more precise value,
use 299,792.458 km/second), calculate the distance between Darmstadt and 67P. For your
information, at the encounter Rosetta with the comet in May 2014, the Earth was about 5 AU
distant from 67P [AU = Astronomical Unit; 1 AU = the distance from the Earth to the Sun
(according to Simeon Barber of the Open University team). Our role now is to explain the
development of the Rosetta Project for public and university audiences, what data are being
collected, what data remain to be collected, and how surprises have been faced and confronted.
A major surprise that occurred in early summer of 2014 was that the shape of the comet 67P was
not that of a spherical snowball or one that had been ablated to an elliptical form; rather the
shape resembled a duck! This surprise meant that extensive mapping of the comet surface had to
be carried out so as to select suitable landing sites for the Philae Lander.
Would you say that your involvement with the Philae lander was one of your more memorable projects you have worked on? If so, could you explain what it was that made it so memorable? Memorable projects? Casting my mind back over the past thirty years or so, I would say that I
have been extremely fortunate, but not necessarily distinguished, in accumulating a small
number of memorable events/projects. The first such event was the 1983 announcement by
Finnigan of the commercialization of the QIT as the ITD™ discussed above. The second was
the award of the 1986 Nobel Prize in Chemistry to my research supervisor, Professor John C.
Polanyi, of the University of Toronto, and to Dudley R. Herschbach and Yuan T. Lee. Three
years later was, indeed, memorable as the year in which our first text on the QIT was published3
and the 1989 Nobel Prize in Physics was awarded to Wolfgang Paul, as discussed above, and to
Norman Ramsay and Hans Dehmelt. 1997 was memorable for discussing with the Open
University group their plan for using a QIT on the Rosetta project, and 2013 was memorable for
the award of C$6,500,000 to the Water Quality Centre of Trent University for the purchase on
new mass spectrometers, which brings us to 2014. As discussed above, when Rosetta answered
the wake-up call on 30th January, 2014, world interest was stirred; later the first mass spectrum
was beamed back to Darmstadt giving rise to great excitement only to be diminished somewhat
when the shape of the comet was discovered and the realization that landing of Philae was going
to be difficult. I rose early on the morning of November 12th, 2014, to discover that Philae had
been launched towards the comet surface some 22 km distant and was proceeding towards the
comet at a walking pace of ~80 cm/s. No problem? The Rosetta Orbiter, Philae, and the comet
were moving as a group at a speed of 55,000 km/h! Unfortunately, a blast of gas issuing from
the top of Philae upon landing, so as to retain contact of Philae with the comet, was not working.
Success depended now on the damping system within Lander’s legs, so as to absorb most of the
kinetic energy upon impact, and the firing of two harpoons into the comet surface to anchor the
system. After a flight time of about 7 hours, Philae landed close to the chosen landing site,
Partners in Research Interview, REM2 7 rebounded about one kilometer from the comet, returned to make a second landing, and
rebounded modestly and settled upon the third landing.
Were there any problems or challenges you faced while working on this project?
Other than the preparation of Chapter 9, and persuading Wiley & Sons to make this
chapter available to the public, I had no problems or challenges.
What was going through your mind when you heard that Philae had made history by being
the first spacecraft to successfully land on the surface of a comet?
I was absolutely astonished to learn of Philae’s successful landing on the surface of
comet 67P about one hour after the actual landing. Because of the enormous difficulties of this
project and the failure of the retaining blast of gas from Philae on landing, I was convinced that
Philae would rebound like a bouncy ball9 and disappear into space. I was jumping up and down
with joy!!
Could you describe a simple scientific concept behind your project, keeping in mind
audiences of elementary and secondary school students?
When ions are trapped or confined within a defined region of space, they continue to
move, that is, they have some kinetic energy and they may collide with background atoms and
molecules. They are trapped in a potential well that has been created by the electric field that is
often shaped like a bowl. Almost any collision will result in a loss of momentum and the ion
will move closer to the bottom of the bowl; within a U-shaped bowl, the ions will move to the
closer to both the bottom of the bowl and the centre of the bowl.
The motion of each ion species, for example, N2+ or CO2+, is characterized by a
frequency usually in the kilohertz or radio region. Just like a bridge or a chandelier or a
wineglass, characteristic frequencies of ions can be excited by externally-generated frequencies
such that their velocity is increased and, in the limit, ions can be ejected in this manner from the
trapping region.
These two concepts cover the collisional focusing of ions to the central axis or point in
space, and the mass-selective ejection of ions from a confining region and subsequent detection
by a detector external to the confining region.
9
Made of polybutadiene. Partners in Research Interview, REM2 8 What are your plans for the future? Are there any new projects coming up for you?
My plans for the future include the identification of the elemental composition of ions by
using ion trapping mass spectrometers of such high mass resolution that the observed
mass/charge ratio can correspond only to one combination of atoms of, for example, carbon,
hydrogen, oxygen, nitrogen, etc. The specific ions of interest are those newly-formed by an ash
tree as a result of attack by the Emerald Ash Borer.
As for new projects, I am hoping to investigate with colleagues at Trent University and at
l’Université d’Aix-Marseille the interactions of proteins, particularly bovine serum albumin (as a
substitute for human serum albumin) with medicinal drugs, such a Ibuprofen, and contaminants
of anthropogenic origin such as polyfluorinated carboxylic and sulphonic acids. In addition, we
are hoping to examine collagen from bone artifacts recovered from ancient aboriginal settlements
and to identify thus the animals from which the collagen is derived.
What advice/encouragement would you give to students who are interested in pursuing a
career in the science field?
Be curious; check (anything of which you are not sure), and check again; study as much
mathematics as you can handle; arrange your affairs, personal and business, in an orderly fashion
(that is, orderly according to your criteria); develop your memory, perhaps by memorizing the
Periodic Table of elements; be energetic; be persistent; do not procrastinate; and enjoy life.
Set your own objectives and do not necessarily accept decisions made by others but that
affect your life. Your are limited only by your own efforts and your own imagination.
Partners in Research Interview, REM2