When I was born in 1904 the electron had only recently been discovered, giving scientists the first clues to the structure of the atom. By the time I had completed my university studies just 24 years later, the theory of quantum mechanics had provided the key to understanding the behaviour and structure of atoms, although there was still much work to be done in this area. The structure of molecules, however, remained elusive. With the exception of a few simple molecules, both molecular structure and its relationship to chemical processes and reactions was largely unknown, and without an understanding of these fundamental relationships we could only guess at the behaviour and properties of most chemical compounds.
I used spectroscopy to discover some of the simplest and most important molecules in the universe and to determine their structure. I measured the wavelengths of the light absorbed or emitted by these molecules; in other words, I studied the molecule's spectrum.
Each molecule or atom has its own unique spectrum, just like each person has a fingerprint which is unique to them. By studying the molecules' spectra, I was able to precisely calculate their rotational, vibrational and electronic energies. This knowledge then allowed me to determine their molecular geometries: the distances between and positions of atoms in the molecule. My work on molecular geometry has been used by other researchers to understand how and why molecules react in a specific way with each other. Perhaps Dr. John Polanyi, who pioneered the field of molecular reaction dynamics, can give you more information on that.
Although I consider myself a physicist, I received the Nobel Prize in Chemistry in 1971. Chemistry and physics overlap so much these days. My work with hydrogen and with free radicals was of particular interest to the Nobel selection committee