I
was born in Mexico City on March 19, 1943; my parents were Roberto Molina Pasquel
and Leonor Henriquez de Molina. My father was a lawyer; he had a private practice,
but he also taught at the National University of Mexico (Universidad Nacional
Autonoma de Mexico (UNAM) ). In his later years, after I had left Mexico, he
served as Mexican Ambassador to Ethiopia, Australia and the Philippines.
I attended elementary school and high school in Mexico City. I was already fascinated
by science before entering high school; I still remember my excitement when
I first glanced at paramecia and amoebae through a rather primitive toy microscope.
I then converted a bathroom, seldom used by the family, into a laboratory and
spent hours playing with chemistry sets. With the help of an aunt, Esther Molina,
who was a chemist, I continued with more challenging experiments along the lines
of those carried out by freshman chemistry students in college. Keeping with
our family tradition of sending their children abroad for a couple of years,
and aware of my interest in chemistry, I was sent to a boarding school in Switzerland
when I was 11 years old, on the assumption that German was an important language
for a prospective chemist to learn. I remember I was thrilled to go to Europe,
but then I was disappointed in that my European schoolmates had no more interest
in science than my Mexican friends. I had already decided at that time to become
a research chemist; earlier, I had seriously contemplated the possibility of
pursuing a career in music - I used to play the violin in those days. In 1960,
I enrolled in the chemical engineering program at UNAM, as this was then the
closest way to become a physical chemist, taking math-oriented courses not available
to chemistry majors.
After finishing my undergraduate studies in Mexico, I decided to obtain a Ph.D.
degree in physical chemistry. This was not an easy task; although my training
in chemical engineering was good, it was weak in mathematics, physics, as well
as in various areas of basic physical chemistry - subjects such as quantum mechanics
were totally alien to me in those days. At first I went to Germany and enrolled
at the University of Freiburg. After spending nearly two years doing research
in kinetics of polymerizations, I realized that I wanted to have time to study
various basic subjects in order to broaden my background and to explore other
research areas. Thus, I decided to seek admission to a graduate program in the
United States. While pondering my future plans, I spent several months in Paris,
where I was able to study mathematics on my own and I also had a wonderful time
discussing all sorts of topics, ranging from politics, philosophy, to the arts,
etc., with many good friends. Subsequently, I returned to Mexico as an Assistant
Professor at the UNAM and I set up the first graduate program in chemical engineering.
Finally, in 1968 I left for the University of California at Berkeley to pursue
my graduate studies in physical chemistry.
During my first year at Berkeley, I took courses in physics and mathematics,
in addition to the required courses in physical chemistry. I then joined the
research group of Professor George C. Pimentel, with the goal of studying molecular
dynamics using chemical lasers, which were discovered in his group a few years
earlier. It was also at that time that I met Luisa Tan, who was a fellow graduate
student in Pimentel's group and who later became my wife and close scientific
collaborator.
George Pimentel was also a pioneer in the development of matrix isolation techniques,
which is widely used in the study of the molecular structure and bonding of
transient species. He was an excellent teacher and a wonderful mentor; his warmth,
enthusiasm, and encouragement provided me with inspiration to pursue important
scientific questions.
My graduate work involved the investigation of the distribution of internal
energy in the products of chemical and photochemical reactions; chemical lasers
were well suited as tools for such studies. At the beginning I had little experience
with the experimental techniques required for my research, such as handling
vacuum lines, infrared optics, electronic instrumentation, etc. I learned much
of this from my colleague and friend Francisco Tablas, who was a postdoctoral
fellow at that time. Eventually I became confident enough to generate original
results on my own: my earliest achievement consisted of explaining some features
in the laser signals - that at first sight appeared to be noise - as "relaxation
oscillations," predictable from the fundamental equations of laser emission.
My years at Berkeley have been some of the best of my life. I arrived there
just after the era of the free-speech movement. I had the opportunity to explore
many areas and to engage in exciting scientific research in an intellectually
stimulating environment. It was also during this time that I had my first experience
dealing with the impact of science and technology on society. I remember that
I was dismayed by the fact that high-power chemical lasers were being developed
elsewhere as weapons; I wanted to be involved with research that was useful
to society, but not for potentially harmful purposes.
After completing my Ph.D. degree in 1972, I stayed for another year at Berkeley
to continue research on chemical dynamics. Then, in the fall of 1973, I joined
the group of Professor F. Sherwood (Sherry) Rowland as a postdoctoral fellow,
moving to Irvine, California, with Luisa; we married in July of that year. Sherry
had pioneered research on "hot atom" chemistry, investigating chemical properties
of atoms with excess translational energy and produced by radioactive processes.
Sherry offered me a list of research options: the one project that intrigued
me the most consisted of finding out the environmental fate of certain very
inert industrial chemicals - the chlorofluorocarbons (CFCs) - which had been
accumulating in the atmosphere, and which at that time were thought to have
no significant effects on the environment. This project offered me the opportunity
to learn a new fieldatmospheric chemistry-about which I knew very little; trying
to solve a challenging problem appeared to be an excellent way to plunge into
a new research area. The CFCs are compounds similar to others that Sherry and
I had investigated from the point of view of molecular dynamics; we were familiar
with their chemical properties, but not with their atmospheric chemistry.
Three months after I arrived at Irvine, Sherry and I developed the "CFC-ozone
depletion theory." At first the research did not seem to be particularly interesting
- I carried out a systematic search for processes that might destroy the CFCs
in the lower atmosphere, but nothing appeared to affect them. We knew, however,
that they would eventually drift to sufficiently high altitudes to be destroyed
by solar radiation. The question was not only what destroys them, but more importantly,
what are the consequences. We realized that the chlorine atoms produced by the
decomposition of the CFCs would catalytically destroy ozone. We became fully
aware of the seriousness of the problem when we compared the industrial amounts
of CFCs to the amounts of nitrogen oxides which control ozone levels; the role
of these catalysts of natural origin had been established a few years earlier
by Paul Crutzen. We were alarmed at the possibility that the continued release
of CFCs into the atmosphere would cause a significant depletion of the Earth's
stratospheric ozone layer. Sherry and I decided to exchange information with
the atmospheric sciences community: we went to Berkeley to confer with Professor
Harold Johnston, whose work on the impact of the release of nitrogen oxides
from the proposed supersonic transport (SST) aircraft on the stratospheric ozone
layer was well known to us. Johnston informed us that months earlier Ralph Cicerone
and Richard Stolarski had arrived at similar conclusions concerning the catalytic
properties of chlorine atoms in the stratosphere, in connection with the release
of hydrogen chloride either from volcanic eruptions or from the ammonium perchlorate
fuel planned for the space shuttle.
We published our findings in Nature, in a paper which appeared in the June 28,
1974 issue. The years following the publication of our paper were hectic, as
we had decided to communicate the CFC - ozone issue not only to other scientists,
but also to policy makers and to the news media; we realized this was the only
way to insure that society would take some measures to alleviate the problem.
To me, Sherry Rowland has always been a wonderful mentor and colleague. I cherish
my years of association with him and my friendship with him and his wife, Joan.
While he was on sabbatical leave in Vienna during the first six months of 1974,
we communicated via mail and telephone. There were many exchanges of mail during
this short period of time, which illustrated the frantic pace of our research
at that time while we continued to refine our ozone depletion theory. Soon after,
Sherry and I published several more articles on the CFC-ozone issue; we presented
our results at scientific meetings and we also testified at legislative hearings
on potential controls on CFCs emissions.
In 1975, I was appointed as a member of the faculty at the University of California,
Irvine. Although I continued to collaborate with Sherry, as an assistant professor
I had to prove that I was capable of ponducting original research on my own.
I thus set up an independent program to investigate chemical and spectroscopic
properties of compounds of atmospheric importance, focusing on those that are
unstable and difficult to handle in the laboratory, such as hypochlorous acid,
chlorine nitrite, chlorine nitrate, peroxynitric acid, etc. It was in those
years that Luisa, my wife, began collaborating with me, providing invaluable
help in carrying out those difficult experiments. We also started then to raise
a family: our son, Felipe, was born in 1977. Initially, Luisa had a teaching
and research position at Irvine; however, after Felipe was born, she decided
to work only part-time so that she could devote more time to Felipe. Fortunately
for me, she decided to join my research group. Throughout the years, she has
been very supportive and understanding of my preoccupation with work and the
intense nature of my research.
Although my years at Irvine were very productive, I missed not doing experiments
myself because of the many responsibilities associated with a faculty position:
teaching courses, supervising graduate students, meetings, etc. After spending
seven years at Irvine as Assistant and then Associate Professor, I decided to
move to a non-academic position. I joined the Molecular Physics and Chemistry
Section at the Jet Propulsion Laboratory in 1982. I had a smaller group - only
a few postdoctoral fellows - but I also had the luxury of conducting experiments
with my own hands, which I enjoyed very much. Indeed, I spent many hours in
the laboratory in those years, conducting measurements and developing techniques
for the study of newly emerging problems. Around 1985, after becoming aware
of the discovery by Joseph Farman and his co-workers of the seasonal depletion
of ozone over Antarctica, my research group at JPL investigated the peculiar
chemistry which is promoted by polar stratospheric clouds, some of which consist
of ice crystals. We were able to show that chlorine-activation reactions take
place very efficiently in the presence of ice under polar stratospheric conditions;
thus, we provided a laboratory simulation of the chemical effects of clouds
over the Antarctic. Also, in order to understand the rapid catalytic gas phase
reactions that were taking place over the South Pole, Luisa and I carried out
experiments with chlorine peroxide, a new compound which had not been reported
previously in the literature and which turned out to be important in providing
the explanation for the rapid loss of ozone in the polar stratosphere.
In 1989 I returned to academic life, moving to the Massachusetts Institute of
Technology, where I have continued with research on global atmospheric chemistry
issues. After taking off for a few years, Luisa rejoined my research group.
Our son is now in college: besides science, he also has an interest in music;
he has been playing piano for over 10 years.
Although I no longer spend much time in the laboratory, I very much enjoy working
with my graduate and postdoctoral students, who provide me with invaluable intellectual
stimulus. I have also benefited from teaching; as I try to explain my views
to students with critical and open minds, I find myself continually being challenged
to go back and rethink ideas. I now see teaching and research as complementary,
mutually reinforcing activities.
When I first chose the project to investigate the fate of chlorofluorocarbons
in the atmosphere, it was simply out of scientific curiosity. I did not consider
at that time the environmental consequences of what Sherry and I had set out
to study. I am heartened and humbled that I was able to do something that not
only contributed to our understanding of atmospheric chemistry, but also had
a profound impact on the global environment.
One of the very rewarding aspects of my work has been the interaction with a
superb group of colleagues and friends in the atmospheric sciences community.
I truly value these friendships, many of which go back 20 years or more, and
which I expect to continue for many more years to come. I feel that this Nobel
Prize represents a recognition for the excellent work that has been done by
my colleagues and friends in the atmospheric chemistry community on the stratospheric
ozone depletion issue.
From Les Prix Nobel. The Nobel Prizes 1995, Editor Tore Frängsmyr, [Nobel Foundation], Stockholm, 1996
This autobiography/biography was written at the time of the award and later published in the book series Les Prix Nobel/Nobel Lectures. The information is sometimes updated with an addendum submitted by the Laureate. To cite this document, always state the source as shown above.