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Professor James Morrison was interviewed in 2010 for the Interviews with Australian scientists series. By viewing the interviews in this series, or reading the transcripts and extracts, your students can begin to appreciate Australia's contribution to the growth of scientific knowledge.
The following summary of Morrison’s career sets the context for the extract chosen for these teachers’ notes. The extract explains how a mass spectrometer works and one of the projects in which Morrison used it. Use the focus questions that accompany the extract to promote discussion among your students.
James Douglas (Jim) Morrison was born in Glasgow, Scotland in 1924. Morrison completed his higher education at Glasgow University with a BSc (Hons) in chemistry (1945) and a PhD during which he was the first person to “see” hydrogen atoms in an x-ray crystal structure (1948). Morrison was also awarded a DSc from Glasgow University in 1958.
In 1949 Morrison left the cold and gloom of Scotland for sunny Australia and a position as a research officer in the division of Industrial Chemistry at the Council for Scientific and Industrial Research (CSIR). At CSIR Morrison changed his focus from x-ray crystallography to mass spectrometry, with great success. One of his major achievements in the field of mass spectrometry was the use of a computer program to sharpen the peaks in mass spectra in 1959. While at CSIR, Morrison was promoted to senior research officer (1953), principal research officer (1956), senior principal research officer (1960) and finally chief research officer (1964).
The newly established La Trobe University in Melbourne offered Morrison the foundation chair of physical chemistry, which he took up in 1967. During his time at La Trobe he constructed one of the first gas chromatography-mass spectrometry (GC-MS) machines in Australia. He then developed the GC-MS technique, again with a focus both on the apparatus and computational analysis of the data. With this new technique and by using computers of ever increasing power, Morrison was able to investigate the chemical components of odours, the constituents of indigenous medicines and detect the molecular difference between a real and a forged ten dollar note! In 1985 Morrison became the chairman of the Chemistry Department at La Trobe University and was made emeritus professor in 1989, upon his retirement.
During his career Morrison went on several fruitful sabbaticals, visiting the University of Chicago (1956-57), Princeton University (1964) and the University of Utah (1971-72), where he became an adjunct professor of the Chemistry Department (1973-2001). He was also the first master of Chisholm College at La Trobe University (1972-77).
Morrison’s numerous career accolades include the Rennie medal (1954) and H. G. Smith medal (1961) from the Royal Australian Chemical Institute, an invitation to the Solvay meeting (1962), the Queen’s Jubilee medal (1977), being made an officer of the order of Australia (1990) and the Australian and New Zealand Society for Mass Spectrometry medal (2009). He was elected a fellow of the Australian Academy of Science in 1964.
What is a mass spectrometer?
I think we’d better describe exactly what a mass spectrometer is.
It’s really not a very complicated machine. JJ Thomson, an English ‘physicist’—I guess you would call him—in 1910 or so discovered that, if you struck an electrical discharge in gas at low pressure, you got a coloured glow and this coloured glow consisted of ions of atoms or molecules that had lost an electron and had an electric charge. He also discovered that these particles could be deflected in a magnetic field and that heavier particles were deflected less than light particles, like hydrogen. Hydrogen particles were deflected very easily and the heavier atoms less so. So, by that means, he discovered that there were two kinds of neon. Up till then, they’d just known of a rare gas called neon. Here he suddenly found two neons, one at mass 20 and one at mass 22, which they called isotopes.
JJ Thomson had two research students—one, Aston, a young Englishman; and Dempster, a young Canadian—and they took this idea of JJ Thomson’s and developed it. Aston built what are called mass spectrographs, where they used photographic plates to detect the ions, whilst Dempster used electrical methods of detection to produce what are called the mass spectrometers. By 1944, these machines had been made with a mass resolution of about one in 250. That is, you could separate atoms with masses up to molecular weight 250, which was just enough to separate the uranium for the atom bomb. But like radar and so many discoveries that were made in England, the commercial applications of it took place in America. In fact, this was where commercial mass spectrometers, while there were very few, were being produced at that time.
So, for chemistry, what could one do? If you take an atom and ionise it, all you get is the atom with a plus charge on it. But, in the case of molecules, they break up so that, for example, if you have carbon dioxide (CO2), you don’t get an ion just at mass 44 corresponding to the mass of CO2 but you also get an ion at mass 28, which is carbon monoxide (CO), an ion at mass 16, which is oxygen (O), and another one at 12 for carbon (C). If you had a more complicated molecule, nearly every chemical bond broke and you got this pattern of ions, which we call a mass spectrum. Here again, these were very characteristic and could be used for identification. But it wasn’t as simple as that either, because the spectra that you got were not always the same; they depended on the temperature of the ion source we were using, they depended on the gas pressure and they depended on the voltages that you used in the instrument. My first job was just to study how ions are made and see if we could produce reproducible mass spectra.
So these mass spectra are essentially a graph with particular lines showing the different fragments.
When you put a molecule into the mass spectrometer, some of the molecules just produce an ion with the plus charge and some of them break bonds so that you get all these various fragments. The mass spectrum comes out as a piece of paper with a list of peak heights versus mass number, which is characteristic of a given molecule.
Aboriginal pharmacopoeia project
There was another fascinating application to do with plants used medically by Aborigines.
Ah, yes. Well, this arose from the fact that the government sent me, in the early 1980s, to China to see what the Chinese were doing with their herbal medicine. I think knowing of my interest in herbs was the reason they sent me and I took with me a small group. To our great surprise, we found that the Chinese were using mass spectrometers, which they’d been given, to examine their herbal medicine. One of the members of my party was Ella Stack, who had been in charge of Aboriginal medicine. It was Ella’s suggestion to say, ‘Why don’t we do a survey of what herbs the Aborigines have been using for 5,000 years and see if we can find out what chemicals are there?’ This started the Aboriginal Pharmacopoeia project, which, it turned out, the Aborigines in the Northern Territory took up enthusiastically. We got swamped with loads of samples of plant material from all over the Northern Territory and we did find some rather interesting chemicals in these and produced a book on the pharmacopoeia.
Give us an example of a chemical or an application of these chemicals.
There was one plant from the Centre and when they were fishing, they’d put the leaves of this plant in the water and all the fish would come up to the surface, unconscious, and they could be gathered up. It was also used for toothache, as they found it was an excellent substance.
An edited transcript of the full interview can be found at http://www.science.org.au/scientists/interviews/m/morrison.
Focus questions
Select activities that are most appropriate for your lesson plan or add your own. You can also encourage students to identify key issues in the preceding extract and devise their own questions or topics for discussion.
ion
isotope
mass spectrometer
molecular weight
pharmacopoeia
spectrum
uranium
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