David Husain: Enterprising physical chemist

From the mid-1960s onwards, David Husain and his colleagues at Cambridge University did pioneering work on the rapidity with which excited atoms reacted with simple molecules such as hydrogen and the light alkanes, processes of great relevance in the context of atmospheric chemistry.

Husain's work with Robert Donovan (later Head of Chemistry at Edinburgh University) was especially intriguing. They discovered that an oxygen atom that had been raised to a high degree of electronic excitation reacted more slowly with hydrogen than an oxygen atom endowed with a lesser degree of excitation, a counter-intuitive result that they later elegantly explained quantum-mechanically. For this, and later pioneering work, Husain was awarded in 1974 the prestigious Corday Morgan prize and later the Tilden prize of the Royal Society of Chemistry. He was elected a Fellow of the Institute of Physics, the Royal Society of Chemistry and a member of the New York Academy of Sciences.

In 1986 he and John Plane (now Professor of Atmospheric Chemistry at Leeds University) published a key paper in the Journal of the Chemical Society, Faraday Transactions ("The Absolute Rate of the Reaction O + NaO > Na + O2 and its Effect on Atomic Sodium in the Mesosphere") that overturned accepted dogma in regard to the origin of the so-called "sodium night glow". This glow occurs in the tails of meteors and also some 50 or so miles in the mesosphere above the earth's surface.

Its origin was a matter of conjecture up until the mid-1960s. Husain's and Plane's paper – to use the words of Harvard University's Nobel prize-winner Dudley Herschbach – "upset the applecart". It prompted Herschbach and many other eminent investigators to probe further the mechanism of the sodium night glow, a phenomenon that is now largely understood. Of Husain's work, Herschbach recently said that "it was always enterprising, always carefully designed and carried out. He aimed to elucidate significant questions."

Born in 1937 of a Muslim Indian Test cricketer and a Jewish mother of Russian extraction, David Husain moved at a tender age from his birthplace, Grimsby, to a somewhat unsettled childhood, first in Cambridge then in London, where he attended Chiswick Grammar School up to A-level standard. He entered Manchester University when, arguably, it had the finest department of chemistry in the world, with giants such as Michael Polanyi, M.G. Evans, John Rowlinson, H.C. Longuet-Higgins and Noel Hush at the helm.

After a first-class honours degree he moved to the Department of Physical Chemistry at Cambridge, where, in 1959, he began his PhD work under R.G.W. Norrish (who shared the Nobel prize in chemistry in 1966). Husain was Norrish's last research student, and his duties included running the head of department's research group as well as undertaking his own work on the kinetics of gaseous reaction for which he was awarded his doctorate in 1962.

In Cambridge he ascended the academic ladder: Demonstrator in 1963, Lecturer in 1968 and Reader in 1986; and he was elected a teaching fellow in Pembroke College, a post he held until his retirement in 2004. Apart from a six-month sabbatical at the Case Institute in Cleveland, he carried out his prize-winning work on the reactivity of atoms and small molecules in Cambridge, where he mentored numerous outstanding PhD students who later took up senior posts in universities and industrial laboratories worldwide.

It was not only as a researcher and research mentor that Husain excelled. He was also a gifted and most effective teacher, especially as a lecturer to undergraduates. He paid meticulous attention to the quantitative facts. But he was also in complete command of the grand sweep of theory and its significance. Nowhere were these qualities more apparent than in his second-year course on statistical mechanics and thermodynamics, where he revelled in communicating the far-reaching consequences of certain central equations that he delighted in deriving on the blackboard. It was his endearing practice to intercalate within these lectures four or five witty anecdotes every hour. Students from other courses, as well as postdoctoral and visiting scientists used to file into the back of the lecture theatre to acquaint themselves or to renew their stock of Husain stories.

Husain was alive to the beauty of Cambridge, its buildings, bridges, gardens, libraries and museums, and to his good fortune in belonging to Pembroke College, of whose distinction and achievements he was immensely proud. The life and work of Nicholas Ridley, Pitt, Stokes, Habakkuk and many other luminaries he could explain at length. Fascinated by European history, about which he read extensively, and blessed with an encyclopaedic memory he could recite, almost verbatim, numerous sources within his formidable library of some 7,000 books. His idol was Bismarck, about whom he could expatiate at length – and he often did in departmental and college meetings.

In talking about his own work he communicated great excitement, genuine academic passion mingled with a charming touch of neurotic punctilio. Visitors and friends were much impressed by his omnivorous curiosity across the entire academic spectrum. His half-brother – a vice-president of a Pepsi-Cola company, very different from the cloistered world that he himself inhabited – spoke at the funeral how the Renaissance quality of the man stood out. But it was Husain's enthusiasm, warm-heartedness, generous and sociable personality that were his prime characteristics. He was totally without self-importance, malice or rancour and an engaging story-teller.

I last saw David Husain a few nights before he died, at a dinner in Peterhouse. Sometimes in Oxbridge and other institutions, when non-academics sit next to certain dons, they have a dismal time because their neighbour turns out to be self-absorbed and superior. That night Husain's transparent kindliness, courtliness and lavish consideration for others was much in evidence. In one of her letters, Jane Austen wrote: "Incline us, O God, to think humbly of ourselves, to be severe only in the examination of our own conduct, to consider our fellow creatures with kindness." These admirable sentiments were embodied in David Husain.

John Meurig Thomas

David Husain, physical chemist: born Grimsby, Lincolnshire 27 November 1937; Demonstrator in Physical Chemistry, Cambridge University 1963-68, Lecturer 1968-86, Reader 1986-2004 (Emeritus); Fellow, Pembroke College, Cambridge 1964-2002; died Cambridge 28 December 2007