Bernhard Gross and electret research: his contributions, our collaboration, and what followed

The 100th anniversary of Bernhard Gross was celebrated at the 12 ^th International Symposium on Electrets in 2005. Gross has inspired and stimulated electret research since the 1930´s when he entered this field as a young scientist. The following article is, to a large part, a personal tribute to his contributions. In the first part, some of the seminal early work of Gross will be discussed. This is followed by reminiscences of the author to joint studies of radiation charging, carrier transport, and other aspects of electrets at Bell Laboratories and at the Darmstadt University of Technology. In the last part, recent work in Darmstadt on charge storage, charge transport, and piezoelectricity of cellular electrets, still in part stimulated and accompanied by Bernhard Gross, will be discussed