Related Experiment Video
Updated: Jun 25, 2026
05:52
Observation and Analysis of Blinking Surface-enhanced Raman Scattering
Published on: January 11, 2018
Interstellar chemistry: a strategy for detecting polycyclic aromatic hydrocarbons in space
F J Lovas1, Robert J McMahon, Jens-Uwe Grabow
1Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
Journal of the American Chemical Society
|March 24, 2005
Summary
Polar polycyclic aromatic hydrocarbons (PAHs) like corannulene are key to confirming PAHs in space. Microwave spectroscopy measured corannulene's dipole moment, enabling radio astronomical identification of these crucial interstellar molecules.
Area of Science:
- Astrochemistry
- Radio Astronomy
- Spectroscopy
Background:
- Polycyclic aromatic hydrocarbons (PAHs) are suspected interstellar molecules.
- Infrared spectra suggest PAH presence, but radio identification is challenging due to low dipole moments.
Purpose of the Study:
- To enable definitive radio astronomical identification of PAHs in space.
- To investigate polar PAHs, such as corannulene, as potential radio astronomical targets.
- To gain insight into interstellar medium chemistry.
Main Methods:
- Acquisition of the high-resolution rotational spectrum of corannulene using Fourier transform microwave spectroscopy.
- Measurement of corannulene's dipole moment via the Stark effect.
Main Results:
- The rotational spectrum of corannulene was successfully obtained.
- A significant dipole moment of 2.07 D was measured for corannulene.
- This measurement confirms corannulene as a polar PAH suitable for radio astronomy.
Conclusions:
- Polar PAHs, exemplified by corannulene, are viable targets for radio astronomical detection.
- The measured dipole moment of corannulene facilitates its identification in interstellar and circumstellar environments.
- This work advances the confirmation of PAHs in space and understanding of astrochemistry.
Related Concept Videos
01:16UV–Vis Spectroscopy: Molecular Electronic Transitions
In Ultraviolet–Visible (UV–Vis) spectroscopy, the absorption of electromagnetic radiation is used to probe the electronic structure of molecules. This technique provides insights into molecular electronic transitions, particularly the movement of electrons between different molecular orbitals. Radiation is absorbed if the energy of the electromagnetic radiation passing through the molecule is precisely equal to the energy difference between the excited and ground states. During this process,...
01:19Gas Chromatography: Types of Detectors-II
In gas chromatography, different detectors are employed to meet specific analytical needs. These detectors are often categorized based on their detection mechanisms and the types of compounds they are best suited to analyze. Thermal Conductivity Detectors (TCD), Flame Ionization Detectors (FID), and Electron Capture Detectors (ECD) represent common categories, each with unique operating principles and applications. However, beyond these, several other detectors are designed for more specialized...
01:23Atomic Spectroscopy: Absorption, Emission, and Fluorescence
Atomic spectroscopy is a vital tool in elemental analysis, both qualitatively and quantitatively. It can be broadly divided into optical spectroscopy, mass spectroscopy, and X-ray spectroscopy methods. The optical spectroscopic methods are atomic absorption spectroscopy (AAS), atomic emission spectroscopy (AES), and atomic fluorescence spectroscopy (AFS). The first step in all three methods is atomization, where the solid, liquid, or solution-phase samples are converted into gas-phase atoms and...
01:30Atomic Emission Spectroscopy: Interference
In atomic emission spectroscopy (AES), high-temperature atomizers excite a broad range of elements and molecules that generate complex emissions from sources such as oxides, hydroxides, and flame combustion products in the flame or plasma. Several strategies can be employed to minimize spectral interferences caused by overlapping emission lines or bands. These include increasing instrument resolution, choosing alternative emission lines, optimally placing the detector in low-background regions,...
01:29Atomic Fluorescence Spectroscopy
Atomic fluorescence spectroscopy (AFS) is an analytical technique that involves the electronic transitions of atoms in a flame, furnace, or plasma being excited by electromagnetic (EM) radiation. When these atoms absorb energy, they become excited and subsequently release energy as they return to their original state. This emitted light, or "fluorescence," is observed at a right angle to the incident beam. Both absorption and emission processes transpire at distinct wavelengths, which are...
01:02Flame Photometry: Overview
Flame photometry, also known as flame emission spectrometry, is a technique used for the qualitative and quantitative analysis of elements present in a sample using a flame as the source of excitation energy. The concept of flame photometry was realized in the early 1860s by Kirchhoff and Bunsen, who discovered that specific elements emit characteristic radiation when excited in flames. The first instrument developed for this purpose was used to measure sodium (Na) in plant ash using a Bunsen...