Iron lines (physics)
In physics, iron lines are the spectral lines of the element iron .
Basics
The neutral iron atom has 26 electrons. According to the rules of quantum mechanics , the probability distributions for their location are given by the atomic orbitals , which are characteristic of the respective element. If one or more electrons in an atom are shifted into energetically higher orbitals (e.g. by impact or by the absorption of light), the atom is in an excited state . The energies of the excited states have well-defined values for each atom, which form its term scheme . An excited atom can give off its excess energy, for example, by emitting a photon , i.e. by generating light or X-rays. The individual atoms then show their element-specific optical line spectrum (the sodium D line is known, for example ). Iron also has a number of characteristic spectral lines, these are present in all spectral ranges. More than 500 iron lines are known in the sun's spectrum. They are also used in metallurgy to detect iron.
Iron K lines in astronomy
In astronomy, more precisely in X-ray astronomy, the strong emission lines of neutral iron in the X-ray range are of great interest. Astronomers observe them in active galactic nuclei , X-ray binary stars , supernovae and black holes . Of particular interest is the broad iron Kα line at a rest energy of the emitting plasma of 6.4 keV (actually two lines at 6.405 and 6.391 keV). The iron-Kβ line has a rest energy of 7.06 keV (two closely spaced lines at 7.057 and 7.058 keV). When examining active galaxies or black holes with the help of X-ray satellites such as Suzaku or XMM-Newton , by measuring the width, frequency, amplitude fluctuations and spectral distribution of the iron Kα line, conclusions can be drawn about the properties of the objects being examined (mass, energy, speed ) be made. It is thus a good means of studying and discovering (since its properties were theoretically predicted) such objects. It is caused by X-ray fluorescence when an electron of iron jumps back from the L to the K shell after the iron has been excited by an X-ray photon or by a collision with a free electron. It is so important because its fluorescence yield is very high and exceeds that of the iron-Kβ line by a factor of about 8. The presence of other elements (for example argon ) can spread and shift the spectral lines.
Web links
- Science online: X-ray lines
- On the origin of the Fe K-alpha line cores in Active Galactic Nuclei at arxiv.org
- Iron lines. In: Spectrum Lexicon of Astronomy. Retrieved January 17, 2018 .
Individual evidence
- ↑ a b Lexicon of Astronomy: Iron Line - Lexicon of Astronomy , accessed on February 11, 2018
- ↑ The chemical composition undeveloped stars of spectral types A and F . January 1995, p. 32, 55 ( limited preview in Google Book search).
- ^ Heinrich Kayser: Textbook of Spectral Analysis . Springer-Verlag, 2013, ISBN 978-3-642-52577-3 , pp. 210 ( limited preview in Google Book search).
- ^ Elements of the eighth subgroup I iron · cobalt · nickel . Springer-Verlag, 2013, ISBN 978-3-662-30606-2 , pp. 17 ( limited preview in Google Book search).
- ↑ 1961ZA ..... 52..254H Zeitschrift für Astrophysik, Vol. 52, 1961ZA ..... 52..254H Pressure broadening and shifting of iron lines by argon atoms. , Page 255, accessed February 11, 2018