I met Karl in 1997 while doing my PhD on III-VI semiconductors under pressure under the supervision of Prof. Alfredo Segura at the University of Valencia (Spain). Alfredo suggest me to do a predoctoral research stay with Karl at the high pressure lab of the MPI for Solid State Research in Stuttgart. There I realised the great variety of experimental high pressure techniques using the diamond anvil cell that Karl had developed, which included X-ray diffraction, Raman scattering, steady-state photoluminescence, and modulated photoreflectance, many of them combined with low temperatures down to 10 K.

Karl offered me to join his research group as a postdoctoral researcher at the MPI in early 1999. In July, I applied to the most prestigious European fellowship, the Marie Curie (now Marie Sklodowska-Curie) fellowship that was stablished just a few years before (in 1996); however, Karl was so kind that offered me to start working at the MPI from September 1999 on without waiting for the fellowship resolution. I will always remember Karl for his support during the hard days of late 1999 and how he taugh me to have a professional behavior with a colleague despite having personal problems with that same person.

At the MPI, I joined to the other two Karl’s postdoctoral fellows (Ingo Loa and Andrej Grezchnick), which were always working in collaboration with many people invited by Karl to the MPI. I will always remember the invited people working in the group and the group-meeting breakfast every Thursday morning, in which we talked about the work performed during the week and Karl help us design the work plan for the next week.

I worked with Karl at the MPI till November 2000 when I joined the Universitat Politècnica de Valencia (UPV, Spain) as an Assistant Professor. Thanks to Karl and his strong collaboration with Prof. Manuel Cardona at the MPI, I had the opportunity to study I-VII, II-VI, and III-V semiconductors and learned the high-pressure Raman scattering technique that I was later able to setup at the UPV.

At the end of 2000 I was very saddened because Karl was very disappointed with me. He wanted me to stay in Stuttgart for at least one year more and suggested me to go to the USA for a second postdoctoral research stay. However, I felt I had learn a lot with him and I had the opportunity to become a professor in Spain; an opportunity I could not even dare to dream of when I join Karl at the MPI one year before. Despite Karl’s dissapointment, he was very generous and let me use his software “DATLAB”, a very good program developed by him, that I have used for almost two decades to get the ruby pressure scale and analyze Raman scattering data since I use it for the first time in 1999. I will always be indebted to Karl for letting me use his program which help me to build my own high pressure research group at the UPV.

Karl Syassen was a very honest and highly respected person and scientist that made his best for high pressure science. Many people will remember him by his accurate and incisive questions at every High Pressure Research Conference he attended. We will always have him in our memory…