New Developments in Matrix Isolation Spectroscopy

Bondybey, V. E.; Smith, and Alice M.; Agreiter, Jürgen

doi:10.1021/cr940262h

Cited by 192 publications

(138 citation statements)

References 231 publications

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“…It is for instance difficult to transfer complex molecules into the gas phase. In such cases, another low-temperature technique, matrix isolation spectroscopy (MIS) (Bondybey et al 1996), is performed. In MIS experiments, the sample molecules are dispersed in a transparent matrix of rare gas atoms such as Ne or Ar kept at cryogenic temperatures of 6.5 K (Ne-matrix) and 12 K (Ar-matrix).…”

Section: Laboratory Datamentioning

confidence: 99%

Abundances of PAHs in the ISM: confronting observations with experimental results

Gredel

Carpentier

Rouillé

et al. 2011

A&A

104

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Context. The identification of the carriers of the diffuse interstellar bands (DIBs) is the longest standing problem in the study of the interstellar medium. Here we present recent UV laboratory spectra of various polycyclic aromatic hydrocarbons (PAHs) and explore the potential of these molecules as carriers of the DIBs. Whereas, in the near IR range, the PAHs exhibit vibrational bands that are not molecule-specific, their electronic transitions occurring in the UV/vis provide characteristic fingerprints. The comparison of laboratory spectra calibrated in intensity with high signal-to-noise observational data in the UV enables us to establish new constraints on PAH abundances. Aims. From a detailed comparison of the gas-phase and Ne-matrix absorption spectra of anthracene, phenanthrene, pyrene, 2,3-benzofluorene, benzo[ghi]perylene, and hexabenzocoronene with new interstellar spectra, we aim to infer the abundance of these PAHs in the interstellar medium. Methods. We present spectra of PAHs measured at low temperature in the gas phase and in an Ne matrix, and present methods to derive absolute absorption cross sections for the matrix and gas phase spectra. We have obtained high signal to noise (S/N > 100) absorption spectra toward five lines of sight with reddenings of E B−V = 1−1.6 mag. The spectra cover the 3050−3850 Å wavelength region where the PAHs studied here show prominent absorption features. Results. From the observations, we infer upper limits in the fractional abundances of the PAHs studied here. Upper limits in the column densities of anthracene of 0.8−2.8 × 10 12 cm −2 and of pyrene and 2,3-benzofluorene ranging from 2−8 × 10 12 cm −2 are inferred. Upper limits in the column densities of benzo [ghi]perylene are 0.9−2.4 × 10 13 and 10 14 cm −2 for phenanthrene. The measurements indicate fractional abundances of anthracene, pyrene, and 2,3-benzofluorene of a few times 10 −10 . Upper limits in the fractional abundance of benzo [ghi]perylene of a few times 10 −9 and of phenanthrene of few times 10 −8 are inferred. Toward CPD −32 • 1734, we found near 3584 Å an absorption line of OH + , which was discovered in the interstellar medium only very recently. Conclusions. The fractional abundances of PAHs inferred here are up to two orders of magnitude lower than estimated total PAH abundances in the interstellar medium. This indicates that either neutral PAHs are not abundant in translucent molecular clouds or that a PAH population with a wide variety of molecules is present.

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Section: Laboratory Datamentioning

confidence: 99%

Abundances of PAHs in the ISM: confronting observations with experimental results

Gredel

Carpentier

Rouillé

et al. 2011

A&A

104

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“…The matrix effects on the outcome of a spectrum can be divided in three categories: inhomogeneous broadening, shifting, and splitting of lines. [12][13][14] As a different approach, the interaction can be weakened by supporting the guest molecule on a rare gas surface. This challenging technique can alternatively be realized by using large rare gas clusters instead of bulk matrices.…”

Section: Introductionmentioning

confidence: 99%

Spectroscopy of 3, 4, 9, 10-perylenetetracarboxylic dianhydride (PTCDA) attached to rare gas samples: Clusters vs. bulk matrices. II. Fluorescence emission spectroscopy

Dvořák

Müller

Knoblauch

et al. 2012

The Journal of Chemical Physics

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The interaction between 3, 4, 9, 10-perylenetetracarboxylic dianhydride (PTCDA) molecules and solid rare gas samples is studied by means of fluorescence emission spectroscopy. Laser-excited PTCDA-doped large argon, neon, and para-hydrogen clusters along with PTCDA embedded in helium nanodroplets are spectroscopically characterized with respect to line broadening and shifting. A fast non-radiative relaxation is observed before a radiative decay in the electronic ground state takes place. In comparison, fluorescence emission studies of PTCDA embedded in bulk neon and argon matrices result in much more complex spectral signatures characterized by a splitting of the different emission lines. These can be assigned to the appearance of site isomers of the surrounding matrix lattice structure.

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“…18 In the past decade, laser ablation has proven to be a remarkably useful tool for the vaporization of metal species for use in matrix isolation studies. 2,9,19,20 This method has the advantage of transferring only a very small heat load to the sample vaporized, which makes cryogenic temperatures at the substrate easier to maintain. In addition, significant excess kinetic energy is imparted to the vaporized atoms, providing sufficient energy for kinetically unfavorable reactions.…”

Section: Methods For Depositing Matrix-isolated Guest Speciesmentioning

confidence: 99%

“…Finally, pulsed deposition sources can be used for simple gases, gases in a discharge, or in conjunction with laser ablation. 9 For true isolation of guest molecules to be achieved, the matrix must provide a nonreactive local environment for the isolated species. Therefore, the most common choices of matrix materials are the noble gases, neon and argon.…”

Section: Inlet For Matrix Hostmentioning

confidence: 99%

“…Strong resonance Raman spectra have been recorded for such near-ultraviolet (UV) absorbing anions as Cl 2 and O 3 in the ionic alkali metal species M C Cl 2 and M C O 3 . 6,7 Finally, the most sensitive technique available for matrix isolation investigations is laserinduced fluorescence, which was pioneered by Bondybey et al 8,9 The same apparatus can be used for laser-Raman and laser-induced fluorescence experiments. 10 It is desirable to monitor the temperature of the deposition substrate during the matrix isolation experiment, since some deposition techniques may result in transfer of large heat loads to the cryogenic substrate.…”

Section: Introductionmentioning

confidence: 99%

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