Liquid helium of liquid water. Helium was first liquefied on July 10, 1908, by the Dutch physicist Heike Kamerlingh Onnes at the University of Leiden in the Netherlands. At that time, helium-3 was unknown because the mass spectrometer had not yet been invented. In more recent decades, liquid helium has been used as a cryogenic refrigerant, and liquid helium is produced commercially for use in superconducting magnets such as those used in magnetic resonance imaging (MRI), nuclear magnetic resonance (NMR), Magnetoencephalography (MEG), and experiments in physics, such as low temperature Mössbauer spectroscopy. The temperature required to produce liquid helium is low because
Frans Michel Penning of Gorinchem on 12 September 1894. Penning attended the University of Leiden. He studied mathematics and physics as a graduate student under Heike Kamerlingh Onnes. Penning's doctoral work involved measuring thermodynamic properties of various gases at extremely low temperatures. Penning received his PhD on June 25, 1923 with a dissertation entitled 'Metingen over isopyknen van gassen bij lage temperaturen' (Measurements on Isometric Density Lines of Gases at Low Temperatures). His father Louwrens Penning, was a popular novelist in the Dutch literary community; most known for romanticizing the Anglo-Boer War. His mother was Adriana Jenneke Machelina Heijmans. Penning married to Margje