In 1995, Mario Molina received a
Nobel prize in chemistry for his work in atmospheric chemistry and the effect of
chlorofluorocarbons (CFCs) on the depletion of the ozone layer. He shared the
Nobel Prize with F. Sherwood Rowland and Paul Crutzen. This was the first time a
Nobel Prize for research into the impact of man-made objects on the environment
was awarded. The discoveries led to an international environmental treaty, which
bans the production of industrial chemicals that reduce the ozone layer. Dr.
Molina was named one of the top 20 Hispanics in Technology, 1998.

Today, Dr. Molina is one of the
world’s most knowledgeable experts on pollution and the effects of chemical
pollution on the environment. Mexican-born scientist Dr. Molina is currently the
Lee and Geraldine Martin Professor of Environmental Sciences at the
Massachusetts Institute of Technology. “It’s very rewarding to see how one can
simultaneously try to work with problems that affect society in a very direct
way,” he says.

Autobiography 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

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

Addendum, May 2006 My wife is
Guadalupe Alvarez; I am no longer married to Luisa Molina. My son Felipe
finished his medical school studies and is now a physician in Boston.; In 2005 I
moved from MIT to the University of California, San Diego, and also to Mexico
City, where I created a new center for strategic studies in energy and

My current work is related to air
quality and global change issues. I collaborate with colleagues from many other
disciplines on the problem of rapidly growing cities with serious air pollution
problems. In Mexico City we have succeeded in improving air quality
significantly, although much work remains to be done. My research group in San
Diego is investigating chemical properties of atmospheric particles. The goal is
to better understand the effect of these particles on clouds and climate.