After postdoctoral stints in Minnesota and California, he moved to UiT – The Arctic University of Norway in 1996, where he has remained ever since. He has had several secondary positions/affiliations: Senior Fellow of the San Diego Supercomputer Center at the University of California San Diego (1997–2004), Outstanding Younger Researcher awardee of the Research Council of Norway (2004–2010), a co-principal investigator at the national center of excellence Centre for Theoretical and Computational Chemistry (2007–2017), and a visiting professor at the University of Auckland, New Zealand, on many occasions (2006–2016). He edited two books, The Smallest Biomolecules: Diatomics and their Interactions with Heme Proteins (Elsevier, 2008), a monograph on the subject, and Letters to a Young Chemist (Wiley, 2011), a popular science book on careers in chemistry research. In 2014, he coauthored Arrow Pushing in Inorganic Chemistry: A Logical Approach to the Chemistry of the Main Group Elements (Wiley) with Steffen Berg, which won the 2015 Prose Award for best textbook in the Physical Sciences and Mathematics. He has served on the editorial advisory board of the Journal of Biological Inorganic Chemistry (1999–2001, 2005–2007) and currently serves on the editorial boards of the Journal of Porphyrins and Phthalocyanines (2000–) and Journal of Inorganic Biochemistry (2007–present). He has authored/coauthored over 250 scientific papers, which have been cited over 12,000 times with an h-index of 64 (according to Google Scholar). In 2022, he received the Hans Fischer Career Award for lifetime contributions to porphyrin science. He is a member of several national and international academies including the European Academy of Sciences and the Academia Europaea.