Vibrational Stark Spectroscopy of Fluorobenzene Using Quantum Cascade Laser Dual Frequency Combs.

We demonstrate the performance of a dual frequency comb quantum cascade laser (QCL) spectrometer for the application of vibrational Stark spectroscopy. Measurements performed on fluorobenzene with the dual-comb spectrometer (DCS) were compared to results obtained using a conventional Fourier transform infrared (FT-IR) instrument in terms of spectral response, parameter estimation, and signal-to-noise ratio (S/N). The dual-comb spectrometer provided similar qualitative and quantitative data as the FT-IR setup in 250 times shorter acquisition time.

Isomerization of cyanopropyne in solid argon.

Cyanopropyne, CH3-C[triple bond, length as m-dash]C-CN, is a simple molecule whose photochemistry is still unexplored. Here we investigate the UV photolysis of this astrophysically significant nitrile trapped in solid argon. The FTIR study was assisted with 15N-isotopic substitution data and with DFT-level computations including the analyses of ground- and excited-state potential energy surfaces.

Infrared Spectroscopy and Mass Spectrometry of CO Clusters during Nucleation and Growth.

CO clusters with 2 to 4300 molecules are characterized with mass spectrometry and infrared spectroscopy in the uniform postnozzle flow of Laval expansions at constant temperatures of ∼29 and ∼43 K. The mass spectra provide independent, accurate information on the cluster size distributions and through magic numbers also on cluster structures. The experimental results are complemented with force field, quantum chemical, and vibrational exciton calculations.

Synthesis and Electronic Phosphorescence of Dicyanooctatetrayne (NCN) in Cryogenic Matrixes.

The rodlike 1,8-dicyano-octa-1,3,5,7-tetrayne (NCN) molecule was synthesized with UV-assisted coupling of rare-gas matrix-isolated cyanobutadiyne (HCN) molecules. Detection of NCN molecule was possible due to its strong orange-red (origin at 618 nm) electronic luminescence. Excitation spectra of this emission (ã Σ-X̃ Σ phosphorescence) gave access to studying the fully allowed H̃ Σ-X̃ Σ UV system of NCN.

Low Temperature Synthesis and Phosphorescence of Methylcyanotriacetylene.

This paper reports on UV-stimulated synthesis of methylcyanotriacetylene carried out in cryogenic rare gas matrixes via coupling of smaller precursors: propyne and cyanodiacetylene. The detection was possible due to the strong visible ã A' → X̃ A phosphorescence of CHCN, discovered in the course of this work. The ensuing measurements of electronic spectroscopy revealed the formally forbidden B̃ E-X̃ A system, as well as the allowed one Ẽ A-X̃ A, with origins at approximately 3.

Cryogenic Photochemical Synthesis and Electronic Spectroscopy of Cyanotetracetylene.

HCN is a molecule of astrochemical interest. In this study, it was produced in cryogenic Ar and Kr matrices from UV-photolyzed diacetylene/cyanodiacetylene mixtures. Its strong phosphorescence was discovered and served for the identification of the compound.

Electronic Spectroscopy of Methylcyanodiacetylene (CH C N).

The results of a study devoted to the electronic spectroscopy of gaseous, solid, and cryogenic matrix-isolated methylcyanodiacetylene (CH C N) are reported. UV absorption and optical phosphorescence spectra of the compound are described here for the first time, and the corresponding vibronic assignments are proposed. UV absorption, studied directly or through the excitation of phosphorescence, revealed the B˜   E--X˜   A system, very weak A˜   A -X˜   A bands, and a strong, broad absorption feature, tentatively identified as D˜   E-X˜   A .

Infrared and Raman Spectroscopy of Methylcyanodiacetylene (CH C N).

A spectroscopic study combining IR absorption and Raman scattering is presented for methylcyanodiacetylene (CH C N). Gas-phase, cryogenic matrix-isolated, and pure solid-phase substance was analyzed. Out of 16 normal vibrational modes, 14 were directly observed.

Density Functional Exploration of C4H3N Isomers.

Molecules having C4H3N stoichiometry are of astrophysical interest. Two of these, methylcyanoacetylene (CH3C3N) and its structural isomer allenyl cyanide (H2CCCHN), have been observed in interstellar space, while several more have been examined in laboratories. Here we describe, for a broad range of C4H3N isomers, density functional calculations (B3LYP/aug-cc-pVTZ) of molecular parameters including the energetics, geometries, rotational constants, electric dipole moments, polarizabilities, vibrational IR frequencies, IR absorption intensities, and Raman activities.

1-methyl-3-octylimidazolium chloride--sorption and primary biodegradation analysis in activated sewage sludge.

Ionic liquids (ILs) are known to be non-volatile and thus to have low potential for atmospheric contamination or intoxication of humans by inhalation. However ILs have the potential to contaminate soil and water as they might be water soluble and can be sorbed onto solids. The investigation of possible natural ways of reducing the concentration of ILs in the environment is of high importance, especially because the requirement for biodegradable chemicals increases, together with pressure for reduction of incineration and landfill waste.