Intrigued byterrestrial magnetism he recorded observations of fluctuations in magnetic intensity in various parts of Sweden, and was charged by the Stockholm Academy of Sciences with the task, not completed until shortly before his death, of working out the magnetic data obtained byHSwMS Eugenie on her voyage around the world in 1851 to 1853.[4]
In 1858, he succeeded Adolph Ferdinand Svanberg in the chair of physics at Uppsala. His most important work was concerned withheat conduction andspectroscopy. In hisoptical researches,Optiska Undersökningar, presented to theRoyal Swedish Academy of Sciences in 1853, he not only pointed out that the electric spark yields two superposed spectra, one from the metal of the electrode and the other from the gas in which it passes, but deduced fromLeonhard Euler's theory of resonance that an incandescent gas emits luminous rays of the same refrangibility as those it can absorb.[2] This statement, as SirEdward Sabine remarked when awarding him theRumford medal of theRoyal Society in 1872, contains a fundamental principle ofspectrum analysis, and though overlooked for a number of years it entitles him to rank as one of the founders of spectroscopy.[4]
From 1861 onward, he paid special attention to the solar spectrum. His combination of thespectroscope with photography for the study of theSolar System resulted in proving that theSun's atmosphere containshydrogen, among other elements (1862), and in 1868 he published his great map of the normalsolar spectrum inRecherches sur le spectre solaire, including detailed measurements of more than 1000spectral lines, which long remained authoritative in questions of wavelength, although his measurements were inexact by one part in 7000 or 8000, owing to the metre he used as a standard being slightly too short.[4]
Front pages of the 1868 copy of "Recherches sur le spectre solaire"
He was the first, in 1867, to examine the spectrum of theaurora borealis, and detected and measured the characteristic bright line in its yellow-green region; but he was mistaken in supposing that this same line, which is often called by his name, is also to be seen in thezodiacal light.[4]
In 1845, Ångström married Augusta Bedoire (1820–1906).[5] She was the daughter of Jean Henric Bedoire and Catharina Henrietta Littorin and belonged to theBedoire family, a Stockholm merchant family ofHuguenot origin.
TheÅngström unit (1 Å = 10−10 m) in which thewavelengths of light and interatomic spacings in condensed matter are sometimes measured is named after him.[6] The unit is also used incrystallography as well as spectroscopy.
The craterÅngström on theMoon is named in his honour.
One of the main building complexes ofUppsala University, the Ångström Laboratory, is named in his honour. This building houses various departments including the Department of Physics and Astronomy, Department of Mathematics, Department of Engineering Sciences, Institute of Space Physics, and the Department of Chemistry.
^abÅngström, A.J. (1852)."Optiska undersökningar" [Optical investigations].Kongliga Vetenskaps-Akademiens Handlingar [Proceedings of the Royal Academy of Science] (in Swedish).40:333–360. Note: Although Ångström submitted his paper to the Swedish Royal Academy of Science on 16 February 1853, it was published in the volume for Academy's proceedings of 1852.German translation:Ångström, A.J. (1855)."Optische Untersuchungen" [Optical investigations].Annalen der Physik und Chemie (in German).94:141–165.. English translation:Ångström, A.J. (1855)."Optical researches".Philosophical Magazine. 4th series.9:327–342.
^Hofberg, Herman (1876).Svenskt biografiskt handlexikon: alfabetiskt ordnade lefnadsteckningar af Sveriges namnkunniga män och qvinnor från reformationen till närvarande tid, efter tryckta källor och medelst nya bidrag samlade och utarbetade (in Swedish). Bonnier.
