scholarly journals Laboratory Electronic Spectra of Carbon Chains and Rings

2013 ◽  
Vol 9 (S297) ◽  
pp. 237-246 ◽  
Author(s):  
L. N. Zack ◽  
J. P. Maier
Keyword(s):  
Gas Phase ◽  
Electronic Spectra ◽  
Multiphoton Ionization ◽  
Ion Trapping ◽  
Electronic Transitions ◽  
Cavity Ringdown Spectroscopy ◽  
Cavity Ringdown ◽  
Carbon Chains ◽  
Diffuse Interstellar Bands ◽  
Optical Wavelengths

AbstractCarriers of the diffuse interstellar bands (DIBs) cannot be definitively identified without laboratory spectra. Several techniques, including matrix isolation, cavity ringdown spectroscopy, resonance enhanced multiphoton ionization, and ion trapping, have been used to measure the electronic spectra of carbon chains and their derivatives. The gas-phase laboratory spectra could then be compared to the astronomical data of known DIBs. The choice of molecules studied in the gas phase depends on the presence of strong electronic transitions at optical wavelengths, the lifetimes of excited electronic states, and chemical feasibility in diffuse astrophysical environments. Collisional-radiative rate models have also be used in conjunction with laboratory spectra to predict absorption profiles under interstellar conditions.

Electronic spectroscopy of the nonlinear carbon chains C4H4+ and C8H4+

2004 ◽  
Vol 82 (6) ◽  
pp. 848-853 ◽  
Author(s):  
Mitsunori Araki ◽  
Pawel Cias ◽  
Alexey Denisov ◽  
Jan Fulara ◽  
John P Maier
Keyword(s):  
Gas Phase ◽  
Electronic Transition ◽  
Electronic Spectroscopy ◽  
Carbon Chain ◽  
Cavity Ringdown Spectroscopy ◽  
Cavity Ringdown ◽  
Carbon Chains ◽  
Diffuse Interstellar Bands ◽  
Phase Spectra ◽  
Electronic Transition Energies

The electronic spectrum of a nonlinear carbon chain radical C4H4+ was observed after mass-selective deposition in a 6 K neon matrix. The corresponding gas-phase spectra of C4H4+ and C4D4+ have been observed in the 512 to 513 nm region and at 710 nm for C8H4+. These were detected in direct absorption by cavity ringdown spectroscopy through a supersonic planar discharge. The electronic transition energies of these nonlinear carbon chain radicals correlate well with those of the polyacetylene cations HCnH+ (n = 4, 6, 8). The observed profiles are reproduced with rotational constants obtained by ab initio geometry optimizations and extrapolation between the ground and excited electronic states. Key words: nonlinear carbon chain, carbon cation, electronic transition, diffuse interstellar bands, molecular structure.

scholarly journals Electronic spectra of carbon chains and rings: Astrophysical relevance?

2008 ◽  
Vol 4 (S251) ◽  
pp. 395-402 ◽  
Author(s):  
Evan B. Jochnowitz ◽  
John P. Maier
Keyword(s):  
Laser Ablation ◽  
Gas Phase ◽  
Electronic Spectra ◽  
Supersonic Jets ◽  
Spectroscopic Methods ◽  
Carbon Chains ◽  
Diffuse Interstellar Bands ◽  
Key Species ◽  
Future Search ◽  
Unstable Molecules

AbstractOur research has focused on the measurement of the electronic spectra of unstable molecules which are presumed to be of relevance to astrophysical observations. Among these are the carbon chains and their ions. Thus we have been using and developing a number of spectroscopic methods to determine their spectra in the gas phase, including absorption via cavity ring-down and REMPI methods. The species are produced in supersonic jets coupled with discharge and laser ablation sources. With the successful laboratory detection of the electronic spectra of a number of key species, such as bare carbon chains Cnn=4,5, comparisons with astrophysical data could be made which lead to interesting implications for the future search for the species which could be responsible for the diffuse interstellar bands. Among the recent relevant observations in the laboratory have been the electronic spectra of carbon rings, Cnn=14,18,22, the development of a method to study transitions in mass-selected ions collisionally relaxed to 20 K and held in a 22-pole radiofrequency trap, and the study of metal containing carbon chains.

Two-Dimensional Correlation Spectroscopy (2D-COS) of Gas-Phase Pyrrole Clusters in a Supersonic Jet: Treatment of Sharp Bands on a Broad Background

2020 ◽  
Vol 74 (4) ◽  
pp. 408-416
Author(s):  
Yoshiteru Matsumoto ◽  
Souichi Tezuka
Keyword(s):  
Ir Spectra ◽  
Gas Phase ◽  
Supersonic Jet ◽  
Correlation Spectroscopy ◽  
Cavity Ringdown Spectroscopy ◽  
Two Dimensional ◽  
Cavity Ringdown ◽  
Correlation Spectrum ◽  
Large Clusters ◽  
Small Clusters

Two-dimensional correlation spectroscopy (2D-COS) is a useful technique to analyze any intensity behavior of optical spectra that exhibit a complicated feature with overlapped bands. In this study, we apply 2D-COS to the infrared (IR) spectra of gas-phase pyrrole (Py) clusters. The NH stretching vibrations of the Py clusters are measured by cavity ringdown spectroscopy. The observed IR spectra of the Py clusters consist of sharp bands, full width half-maximum (FWHM) ∼1 cm−1, and a broad background (FWHM >50 cm−1). The 2D asynchronous correlation spectra reveal that the sharp bands and a broad background are assigned to small clusters of dimer to pentamer and large clusters with bulk-like structures, respectively, which support the results of our previous study. The sharp bands are also analyzed using another 2D asynchronous correlation spectrum, which is obtained by decomposing the observed IR spectra into sharp and broad components. Because the asynchronous signals are consistent with those obtained from the IR spectra without decomposition, the result would suggest that we need not to decompose the IR spectra into sharp and broad components before applying 2D-COS. However, our model simulations of 2D-COS showed a counterexample that gives an incorrect result without removing a broad background component from the IR spectra. This study strongly suggests that we need to undertake a careful treatment of the complicated IR spectrum with various widths of bands.

Gas-Phase Electronic Transitions of Carbon Chain Anions Coinciding with Diffuse Interstellar Bands

1998 ◽  
Vol 506 (1) ◽  
pp. L69-L73 ◽  
Author(s):  
M. Tulej ◽  
D. A. Kirkwood ◽  
M. Pachkov ◽  
J. P. Maier
Keyword(s):  
Gas Phase ◽  
Carbon Chain ◽  
Electronic Transitions ◽  
Diffuse Interstellar Bands

scholarly journals Polyacenes and diffuse interstellar bands

2019 ◽  
Vol 625 ◽  
pp. A41 ◽  
Author(s):  
A. Omont ◽  
H. F. Bettinger ◽  
C. Tönshoff
Keyword(s):  
Gas Phase ◽  
Current Knowledge ◽  
Visible Range ◽  
High Symmetry ◽  
Carbon Chains ◽  
Diffuse Interstellar Bands ◽  
Carbon Compounds ◽  
Laboratory Results ◽  
Polycyclic Aromatic ◽  
Recent Laboratory

The identification of the carriers of the diffuse interstellar bands (DIBs) remains to be established, with the exception of five bands attributed to C60+, although it is generally agreed that DIB carriers should be large carbon-based molecules (with ~10–100 atoms) in the gas phase, such as polycyclic aromatic hydrocarbons (PAHs), long carbon chains or fullerenes. The aim of this paper is to investigate more specific possible carriers among PAHs, namely elongated molecules, which could explain a correlation between the DIB wavelength and the apparent UV resilience of their carriers. More specifically, we address the case of polyacenes, C4N+2H2N+4, with N ~ 10–18 fused rectilinear aligned hexagons. Polyacenes are attractive DIB carrier candidates because their high symmetry and large linear size allow them to form regular series of bands in the visible range with strengths larger than most other PAHs, as confirmed by recent laboratory results up to undecacene (C46H26). Those with very strong bands in the DIB spectral domain are just at the limit of stability against UV photodissociation. They are part of the prominent PAH family of interstellar carbon compounds, meaning that only ~10−5 of the total PAH abundance is enough to account for a medium-strength DIB. After summarizing the limited current knowledge about the complex properties of polyacenes and recent laboratory results, the likelihood that they might meet the criteria for being carriers of some DIBs is addressed by reviewing the following properties: wavelength and strength of their series of visible bands; interstellar stability and abundances, charge state and hydrogenation; and DIB rotation profiles. No definite inconsistency has been identified that precludes polyacenes from being the carriers of some DIBs with medium or weak strength, including the so-called C2 DIBs. But, despite their many interesting properties, additional experimental data about long acenes and their visible bands are needed to make robust conclusions.

Gas phase electronic spectra of carbon chains Cn(n = 6–9)

2014 ◽  
Vol 16 (3) ◽  
pp. 1161-1165 ◽  
Author(s):  
Xiaojing Chen ◽  
Mathias Steglich ◽  
Varun Gupta ◽  
Corey A. Rice ◽  
John P. Maier
Keyword(s):  
Gas Phase ◽  
Electronic Spectra ◽  
Carbon Chains

scholarly journals Electronic spectra of carbon chains of relevance to astrophysics

1997 ◽  
Vol 178 ◽  
pp. 287-294
Author(s):  
John P. Maier
Keyword(s):  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Spectra ◽  
Homologous Series ◽  
Electronic Absorption Spectra ◽  
Absorption Bands ◽  
Carbon Chains ◽  
Diffuse Interstellar Bands ◽  
Spectroscopic Characteristics

The electronic absorption spectra of a variety of carbon chains have been identified in the laboratory. The measurements were carried out in 5 K neon matrices on mass-selected species. On the basis of the trends evident in the homologous series, it can be predicted in which region absorption bands of the carbon chains are to be expected for the not yet measured longer and isoelectronic species. The spectroscopic characteristics, photostability and structural considerations point out which and what size carbon chains could be the diffuse interstellar bands absorbers.

Gas phase electronic spectra of the linear carbon chains HC2n+1H (n=3–6,9)

2003 ◽  
Vol 119 (2) ◽  
pp. 814-819 ◽  
Author(s):  
H. Ding ◽  
T. W. Schmidt ◽  
T. Pino ◽  
A. E. Boguslavskiy ◽  
F. Güthe ◽  
...  
Keyword(s):  
Gas Phase ◽  
Electronic Spectra ◽  
Carbon Chains
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