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Updated: Jul 27, 2025

Scattering And Absorption of Light in Planetary Regoliths
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Scattering And Absorption of Light in Planetary Regoliths

Published on: July 1, 2019

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一个富有尘埃的星系中芳香碳排放的空间变化

Justin S Spilker1, Kedar A Phadke2,3, Manuel Aravena4

  • 1Department of Physics and Astronomy and George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A&M University, College Station, TX, USA. jspilker@tamu.edu.

Nature
|June 5, 2023
PubMed
概括

早期的星系显示出强烈的多环芳香碳化合物 (PAH) 发射,这表明恒星形成在黑洞活动中占主导地位. 在PAH光的空间变化表明局部过程影响早期的星系进化.

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NMR Spectroscopy of Aromatic Compounds

Aromatic compounds can be identified or analyzed using proton NMR and carbon‐13 NMR. Typically, aromatic hydrogens or hydrogens directly bonded to the aromatic rings are strongly deshielded by the aromatic ring current. Therefore, they absorb in the range of 6.5–8.0 ppm in proton NMR spectra. For instance, aromatic hydrogens directly bonded to the benzene ring absorb at 7.3 ppm. However, aromatic hydrogens of larger rings absorb farther upfield or downfield than the ideal range.
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When solids, liquids, or condensed gases are heated sufficiently, they radiate some of the excess energy as light. Photons produced in this manner have a range of energies, and thereby produce a continuous spectrum in which an unbroken series of wavelengths is present.
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π Electron Effects on Chemical Shift: Aromatic and Antiaromatic Compounds

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Neutral hydrocarbons like cyclopentadiene with an odd number of carbon atoms and one intervening CH2 group in the ring are not aromatic. Cyclopentadiene with 4 π electrons does not satisfy the 4n + 2 π electron rule. Additionally, the intervening CH2 group is sp3 hybridized and lacks a vacant p orbital, thereby interrupting the overlap of p orbitals in a continuous manner and preventing the delocalization of π electrons throughout the ring.
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