Optimism, persistence and good humor were the best allies in the life of Hedwig Kohn, a German scientist, ahead of her time and a pioneer in research in atomic and molecular spectroscopy. The Nazi regime prevented him from teaching at the university and had to flee for his life. Despite being known and recognized for her merits in her country, she was almost 50 years old, persecuted, without a work permit to leave Germany and being a great unknown in the world.
Over time, and after touring numerous countries, Kohn recovered his research and returned to rebound as a teacher in the United States, his final destination. There she again occupied the position of outstanding scientist in the subjects that the Nazi regime had prevented her from developing because she was a Jew and a woman.
Hedwig Kohn was born on April 5, 1887, in Wroclaw, province of Silesia and one of the most important cities of the German Empire. She was the daughter of Georg Kohn, a clothing wholesaler, and Helene Hancke, a descendant of a wealthy family. He only had one brother, Kurt.
The young Kohn, always applied in the studies, was ahead of her time, since she entered the university in 1907, a year before women could enroll in university studies. This situation, which today we would recognize as being of great value, was not easy for her, as she would later recognize, since at the beginning she was not allowed to officially enroll and had to attend class as a guest student.
Kohn obtained his PhD in Physics with Professor Otto Lummer in 1913 and was soon named his assistant when he saw her great talent. He, already famous for the precision of his radiation measurements, was his mentor in physical science who was determined to investigate. In this way, during the First World War Hedwig worked as a teacher and tutor for several doctoral students and, despite her youth, she was recognized and decorated for this work. In fact, he always lived in the Institute of Physics of the university.
Lummer trained Kohn in the quantitative determination of the intensity of light, both from broadband sources and in a blackbody, and from the discrete emission lines of atoms and molecules. In addition, Kohn developed these methods during his career and devised different ways of extracting information from intensity measurements and the shapes of emission lines.
After years of teaching in which the young Kohn led the career of many doctoral students and developed their research, something was beginning to change in the scientific world to grant her the authorization to teach at the university in 1930. She had tried to get that recognition much earlier, in 1919, but the dean explained that the rules clearly specified that this qualification was only "for young men".
His quiet life and dedicated to science did not last long. Kohn was dismissed from office in 1933 due to Nazi regulations that forbade Jews to hold public office and his life began to move between uncertainty and hardship. In 1935 he was offered a three-month stay in Switzerland to measure the intensity of the sun's ultraviolet light, although he did not have time to develop his research. For a time he survived with contracts in lighting companies, but in 1938 he found himself without work, without financial resources and very close to becoming a victim of the Holocaust.
On the fateful day known as the Night of the Broken Glass, Kohn realized that he had to flee as soon as possible to save his life, but he did not have a job offer to do so and he was also a woman alone and almost 50 years old. . The mediation of Rudolf Landenburg, professor who directed the doctorate of Hedwig Kohn, it was providential to help her find a job and, with the help of the International Federation of University Women and the Council for Academics at Risk, she was able to get a job at the University of Aberdeen.
However, the conflict spread in such a way that the war caused England to immediately cancel all the work visas it had granted. Along with Kohn, two other women found themselves in the same situation, forced to flee Germany for the persecution of anti-Semitism and rejection. Lise Meitner and Hertha Sponer, physical scientists like Kohn, and who had also achieved the qualification to teach at the university, were also forced to start from scratch abroad.
During those difficult moments, Kohn, Meitner, Sponer and Ladenburg exchanged many letters with the representatives of the International Federation of University Women and several universities around the world. In the end, they got three vacancies for them with a duration of one year in the United States: one in the Women's School of the University of North Carolina, another in the Sweet Briar College, in Virginia and another one in the Wellesley College, in Massachusetts . The possibility of work of Kohn opened an intermediate way with a visa to go to Sweden in 1940 and did not hesitate. There he stayed for a while before obtaining the visa for the United States and settling there permanently. Later, he learned that his only brother, Kurt, was deported to Kaunas and subsequently murdered.
The flight of Kohn's Nazi regime, to teach at the Women's College of the University of North Carolina in Greensboro, took her first to Berlin, and then to Stockholm, Leningrad, Moscow, Vladivostok, Yokohama, San Francisco and, Finally, Chicago. He left the Swedish capital in 1940, traveled on the Trans-Siberian train to Vladivostok and arrived in the United States two months later, very sick. At the Women's College of the University of North Carolina he spent a year and a half, since in 1942 he began teaching at Wellesley College in Massachusetts.
There she was a professor until she retired in 1952 and continued with a modest laboratory to investigate with her students, where she used the technique of flame spectroscopy. The year of her retirement, in 1952, the Government of the Federal Republic of Germany granted her the title of professor emeritus.
Hedwig Kohn She has authored numerous publications on flame photometry and optical spectroscopy, and is a member of the Die American Physical Society, Die American Association of Physics Teachers and Sigma Xi.
After her retirement, she worked as a researcher at Duke University, where Hertha Sponer, then a professor of Physics there, offered her a position as associate researcher, and continued directing the work of doctoral students and electing other postdoctoral students to study with it spectroscopy of flames, measuring the absorption characteristics and the concentrations of most burning atomic species. This work was basically a continuation of what he did forty years before, between 1912 and 1933.
She died in 1964 at age 76, being active in her research and always surrounded by students until shortly before her death but leaving a great scientific legacy and an example of continuous improvement and perseverance in her life.
During his career, Kohn focused on the quantitative measurement of the intensity of radiation, and mainly focused on luminosity and temperature. In addition, he wrote several chapters of a physics textbook titled Mueller-Pouillets Lehrbuch der Physik (1929). There is no doubt that his contributions and research laid some foundations of physics. In fact, he wrote 270 pages in the main text of Physics of the 1930s and 1940s in Germany, received a patent and wrote numerous articles in scientific journals, some of which continue to be a reference today.