Prof. P. K. Carroll, Nov 16^th.

For at least half a century there has been an almost unbroken tradition for spectroscopic research in Dublin. The present talk will begin with an account of the work of Thomas Preston (1860 - 1900) and Walter N. Hartley (1846 - 1913). Preston's most important work was his study of the Zeeman effect, his first publication on which appeared within nine months of Zeeman's original report in 1897. He worked with stronger magnetic fields than Zeeman under much higher resolution and recorded his spectra photographically. Among his important discoveries were the so-called anomalous Zeeman effect and the identification of regularities in the splittings observed in spectral series. Hartley carried out pioneering work on a number of topics: the absorption spectra of molecules in the ultraviolet; the observation and measurement of atomic emission spectra; the discovery of the spectrum of ozone and its atmospheric importance; the use of wavenumber instead of wavelength in the interpretation of spectra. The significance of these and other achievements will be assessed. Other topics to be discussed will be Adeney's work on high resolution atomic spectroscopy, astronomical spectroscopy at Dunsink observatory and some highlights of molecular spectroscopy in UCD. A brief account of the initial experiments in the development of the dual laser plasma technique for time resolved absorption studies will also be given.

Prof. P. K. Carroll was born in Dublin and received his university education in UCD where he was awarded the B.Sc. degree in 1948. He spent periods as Assistant Lecturer in UCC and the Queen's University of Belfast and was awarded the degree of Ph.D. in 1953. He won a postdoctoral fellowship to the National Research Council of Canada in Ottawa and worked for two years in the spectroscopy division under the direction of G. Herzberg. After a period back in UCD as College Lecturer he spent three years as Research Associate with R. S. Mulliken at the Laboratory for Molecular Structure and Spectra of the University of Chicago. He returned to UCD in 1965 as Associate Professor, was awarded the D.Sc. degree in 1974 and was appointed Professor of Optical Physics in 1976. From 1981 to 1984 he served as Head of the Physics Department. Prof. Carroll's early research was in high resolution studies of the electronic spectra of molecules but in 1975 he began a new programme of research on atomic spectra using laser techniques with special reference to the study of absorption of ionized atoms in the XUV spectral region. In 1988 he was presented with the Boyle Medal, awarded by the Royal Dublin Society for achievement in scientific research.