Remembering Horst Conrad

July 06, 2020
The Physicist Horst Günther Conrad, who worked at the Surface Physics and Molecular Physics Departments for more than 30 years, sadly passed away in March this year. The FHI will miss a patient scientist and educator.

Horst Conrad was a group leader, who worked at the Fritz-Haber-Institute from 1981 until 2012. Though he had been retired for 8 years, many here remember him fondly and were deeply saddened to hear of his death at the early age of 72. “Conrad had helped shape the Institute’s research profile for many years, and provided depth and breadth in the German surface science community for several decades”, says Prof. Gerard Meijer, Managing Director and Director of the Molecular Physics Department.

The beginning of Conrad’s research career took place in Hannover in the 1970s, where the young Gerhard Ertl, who later joined the FHI and was awarded with the Nobel Prize in Chemistry in 2007, took up his first professorship at the Technical University. Prof. Ertl supervised Conrad’s Diplomarbeit in Physics, which he passed with distinction, and subsequently Conrad moved with him to Ludwig Maximilians University of Munich in 1973 to do his PhD. “The research group with Conrad in Munich was a powerful union, all of them graduated very successfully and moved on to have great careers, be it in academia or in industry”, remembers Ertl. 

At the forefront of Conrad’s doctoral research was the investigation of the structure and reactivity of metal and semi­conductor surfaces. It was an exciting time in surface science: From the late 1960s onwards, it had been possible to perform such experiments on clean, well-defined, single crystal surfaces. Several important papers from the Ertl group with Horst Conrad as first author appeared at this time, in particular on the adsorption of atoms and small molecules on palladium surfaces investigated with low energy electron diffraction (LEED), thermal desorption spectroscopy, work function changes and later photoemission. After his PhD, which he also passed with distinction, Horst Conrad embarked on an entirely new experiment in the Ertl group: the application of Penning ionization spectroscopy to the adsorbate problem, with the hope of obtaining perhaps more precise information on adsorbate-induced electronic states than with photoemission.

In 1981 Horst Conrad accepted an offer to join the newly established Department of Surface Physics at the Fritz-Haber Institute of the Max-Planck Society in Berlin, headed by Prof. Alex Bradshaw. This enabled him and his group to build an optimized Penning spectrometer and to make several further advances in an area that would remain his main scientific interest for several years to come. Conrad also had particularly good eye for hiring talented and skilled colleagues, remembers Alex Bradshaw. “He worked with Martin Kordesch on vibrational spectroscopy of various molecules on metal surfaces, in particular on those con­taining the chemically interesting -CN group,” explains Bradshaw, “and Kordesch is now Professor in the Physics Department of the University of Ohio”. Horst Conrad later worked with Ignacio Pascual on vibrational spectroscopy of adsorbates in the Department’s 4K STM. This led to several highly cited papers in prestigious journals, in particular on so-called single-molecule chemistry. Shortly after, Pascual was appointed Professor of Physics at Freie Universität Berlin, and is now Ikerbasque Research Professor at NanoGUNE in Spain.

After Bradshaw left the FHI in 1998, the Surface Physics Department was succeeded by the new Molecular Physics Department under the direction of Prof. Gerard Meijer. Horst Conrad became a stalwart member of the new Department, working on a project where polar molecules were manipulated using electric field gradients produced by micro-structured electrodes. The ultimate goal was to produce a variety of molecular manipulation tools, including lenses, mirrors, guides, conveyer belts, decelerators, storage rings and traps, all integrated on a chip.

Horst Conrad will be remembered for many things, not least for being amusing and imaginative. Our most fond memory though is that of his willingness, skill and patience in explaining complex issues, particularly in physics, to students and young scientists. “They would almost literally queue up outside his office to discuss their results, and would not necessarily be from his group or even from the Department”, Bradshaw recalls. One of them was Prof. Karsten Reuter, who is now the newly appointed Director of the Theory Department. Horst Conrad was one of Reuter’s closest collaborators in his early days at the FHI in the early 2000s: “He spent endless hours teaching me catalysis and surface science experiments. His humble, purely science and content focused manner was extraordinary.”

Horst Conrad was a great educator, as well as a meticulous researcher. He accepted the intellectual challenge to understand everything down to the smallest detail and to his satisfaction. He will be dearly missed.

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