Professor Robert Schuler Dies at age 91

Author: Laura Mortlock-McMinn

We are saddened to report that Zahm Professor Emeritus Robert H. Schuler, passed away the morning of November 13, 2017. Bob Schuler was Director of the NDRL from 1975 to 1995, a 20-year period of growth and productivity that helped build our strong national and international reputation. In addition to his significant research accomplishments and recruiting and development successes, he was instrumental in constructing bridges to radiation chemistry groups in many countries throughout the world, the benefits of which are still felt today. His legacy continues to inform and support us.

Robert H Schuler – a scientific retrospective

Early career 

From his early days as a graduate student in chemistry here at Notre Dame working, under the supervision of William Hamill, with the Physics Department’s heavy-ion accelerator, then located in the basement of what is now the LaFortune student center, Bob’s research was devoted to radiation chemistry, understanding and quantifying the changes induced by the interaction of radiation with matter. He graduated in 1949.

 

Immediately following his PhD studies, he took a position as an assistant professor at his alma mater, Canisius College in Buffalo (B.S. 1946), where the radiation source was now principally X-rays, using a generator again borrowed from physics, and his lifetime interest in the use of iodine as a marker of radiation-induced changes was sparked. His move to the Brookhaven National Laboratories a few years later in 1953 gave access to a much wider variety of radiation sources including heavy ions from the BNL cyclotron with Augustus Allen and access to a broad range of nuclear fragmentation products including alpha and beta particles, neutrons, and high energy bremsstrahlung. The groundwork of much later research into dosimetry and radiation quality effects was, no doubt, laid here.

 

Bushy Run (1956-1976)

 

In 1956 he was appointed, at a very young age, as Director of the Radiation Research Laboratories at what was then the Mellon Institute. The title of Professor of Chemistry was added to his Directorship when the Institute became Carnegie-Mellon University in 1967. During his time at these so-called Bushy Run laboratories, Bob’s focus on quantification of radiation effects sharpened and much effort was expended to understand the differences in energy deposition characteristic of the wide variety radiation sources now at hand. In efforts to identify the various transient species generated by the impact of radiation, new experimental techniques were acquired and new minds were enlisted to push this quest forward.

 

The developments in electron spin resonance (ESR) spectroscopy made in collaboration with Dick Fessenden were particularly significant at this time and led to the publication of their magnum opus, an almost 50-page article in the Journal of Chemical Physics on transient alkyl radicals which has been cited almost 2000 times to date. This ground-breaking partnership was also responsible for the discovery of the phenomenon of chemically-induced dynamic electron spin polarization, a signal of the imbalance in spin populations at short times caused by spin-dependent chemical reaction rates.

 

Reaction rates of radiation induced reactions and the effect of additives in scavenging the radiation-induced transients initially formed was brought into sharp focus, work which led to the development of the Warman-Asmus-Schuler equation, an innovative yet simplifying descriptor of complex processes. Both John Warman and Klaus-Dieter Asmus also went on to distinguished careers in radiation sciences, the former at the Delft University of Technology, the latter at the Hahn-Meitner Institute in Berlin and later as Director here at the NDRL. Pierre Infelta and Stephan Rzad joined Bob and John at Pittsburg in further development of the kinetics of primary processes in irradiated systems.

Hydrocarbon media were probed in much of the early work, building a later bridge to the the Hungarian Academy Institute of Isotopes in Budapest through Gabor Foldiak and Laszlo Wojnarovits. The earliest focus on aqueous solutions centered on hydrated electron and hydroxyl radical rates. Work on the hydrogen atom, a much less prevalent species at least at neutral pH, was initiated by the arrival of Pedatsur Neta who also made significant contributions at the NDRL before moving to the National Institute of Standards and Technology in Gaithersburg. The atomic oxygen negative ion, the supposed complementary base of the hydroxyl radical was also key in the work with Neta and studies on the oxidation of phenol formed the basis for another of Bob’s career spanning interests in phenoxyl radicals.

NDRL (1976-1995)

1976 saw the merger of the Carnegie-Mellon operation and the Notre Dame Radiation laboratory with Schuler moving back to Indiana as the new Director, a post he was to hold for twenty years. During that time, with ample support from the Department of Energy and its forerunners, Bob was able to initiate a substantial broadening of the scope of radiation-related research. Significant prompt developments directly related to the needs of radiation chemical investigations included the construction of a work-horse pulsed linear electron accelerator and efforts to completely define the scavenging processes in irradiated aqueous solutions with careful time-resolved optical absorption spectroscopy assisted by Larry Patterson and Eberhard Janata from Berlin. The suite of techniques aimed at also securing the identity of the transient species was broadened from the ESR approach with Fessenden by the introduction of time-resolved resonance Raman spectroscopy in collaboration with Tripathi. The heavy ion work was again pursued using both the local accelerators in physics and those at more distant locations when necessary in collaboration with LaVerne, still active at the NDRL.

 

Expanding his vision, complementary photochemical efforts in both organic and inorganic solution chemistry were initiated. Photochemistry was later broadened into heterogeneous systems, a forerunner of the community’s later love affair with nanoscience. The heavy ion work was again pursued using both the local accelerators in physics and those at more distant locations when necessary and in collaboration with Jay LaVerne, still active at the NDRL.

 

Though not directly involved in that research, Bob had the insight to realize the importance of theoretical support for these endeavors and invested in both quantum chemistry and track structure simulation capabilities. He also had the foresight to realize the ongoing importance of reliable data curation and supported the Radiation Chemistry Data Center, under the guidance of Alberta Ross, to compile and evaluate all relevant reported data on critical processes such as reaction rates of the key radiolytic transients.

 

Visiting Professorships in India (1980), at the University of Madras and Israel (1985) at the Hebrew University built bridges with the radiation science communities there that persist to this day. The award of the Maria Skłodowska-Curie Medal from the Polish Association for Radiation Research indicated the link also with the community in Poland, particularly at the Institute for Nuclear Chemistry and Technology in Warsaw.

Emeritus

After retiring from the NDRL Directorship in 1995, Bob returned to an early interest in the chromatographic quantification of final product yields in radiolytic processes, and with the assistance of Guadaloupe Albarran, produced many new results with his beloved phenoxyl radicals. His bibliography reached almost 250 published works each characterized by careful, thorough explication and polished writing.