Prof. Matsumoto visited the laboratory of Prof. Otto Dopfer at Technical University Berlin on December 5-16 2022. This was the opportunity for our collaborative study supported by the JSPS Bilateral Exchange Program between Japan and Germany. We proceeded to write our manuscript on IR photodissociation spectroscopy of microhydrated pyrrole cations with a lot of fruitful discussions. Fortunately, our paper “Microhydration of the pyrrole cation (Py+) revealed by IR spectroscopy: Ionization-induced rearrangement of the hydrogen-bonded network of Py+(H2O)2” was published in the Journal of Physical Chemistry A (https://doi.org/10.1021/acs.jpca.3c00363).