Infrared spectra of urea isolated in a solid argon matrix

Pure monomeric urea molecules, free of contamination with decomposition products, have been obtained by sublimation of solid urea at ca 30°C and isolating in argon at ca 10K. Very high dilution is required to obtain the pure monomer which shows many spectral features different from that previously reported by King [Spectrochim. Acta28A, 165 (1972)]. The i.r. spectrum of the deutero-analogue has also been measured.     

Infrared spectra of some uranium oxyfluoride molecules isolated in solid argon

Reaction of laser-ablated uranium with oxygen/fluorine mixtures or laser-ablated uranium dioxide ceramic with fluorine produces the uranium oxyfluorides molecules UO₂F₂, UO₂F and UOF₄, which have been isolated in solid argon and identified by virtue of the effects of oxygen isotopic substitution on their infrared spectra.     

Infrared spectra of tetracyanothiophene anion radicals

Infrared spectra of anion radicals of tetracyanothiophene were recorded at −78°C. Large difference of the spectra was observed between the neutral molecule and the anion radicals and was interpreted by the change in the electronic structure.     

Infrared spectra of alkyl vinyl acetals

Summary The infrared spectra of a number of alkyl vinyl acetals were taken.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 1721–1722, September, 1964     

Infrared absorption spectra of 2,2-dibromobutane

The possible existence of geometrically isomeric forms of the title compound, CH₃CBr₂CH₂CH₃, has been investigated by i.r. spectroscopy. It was found that the general features of the spectra can be interpreted reasonably in terms of only one conformation of the molecules in the liquid state. Further confirmation of this view, based on a brief comparison of the liquid phase spectra of CH₃CBr₂CH₂CH₃ and CH₃CHBrCHBrCH₃ is given. Vibrational assignments have been made for most of the fundamental bands assuming C_s molecular symmetry.     

Infrared absorption spectra of As-Se glasses

IR absorption spectra of As-Se glasses have been studied over a wide range of compositions. Various two-phonon, multiphonon (combination tones) and impurity absorptions have been identified. Compositional variation of relative band intensities has been explained in terms of the chemically ordered network model.     

Infrared spectra of matrix isolated and solid ethylene. Formation of ethylene dimers

Spectra of matrices with ethylene/argon ratios from 1/1 to 1/999 and a 1/24 ethylene/xenon matrix have been recorded in the temperature range 15–105 K. From relative i.r. intensities, frequency shifts and statistical calculations, the data are interpreted in terms of a monomer → dimer → aggregate → crystal scheme. It is proposed that the dimer, (C₂H₄)₂, has D_2d symmetry with a structure determined by quadruple hydrogen bonding and hydrogen-hydrogen repulsion. A method is described for calculation of the vibrational splitting due to interactions between the dimer molecular constituents.Solid ethylene has been studied between 15 and 85K. A transformation between two crystalline phases is characterized.     

Infrared absorption spectra of trialkyl orthovanadates

Conclusions The IR spectra of seven trialkyl orthovanadates were studied. The absorption bands of the V=O and V-O bonds in the spectra of these compounds are found respectively in the 960–1012 and 600–662 cm^–1 regions.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2812–2814, December, 1972.     

Isomers of NCO2: IR-absorption spectra of ONCO in solid Ne

Irradiation of a Ne matrix sample containing NO and CO near 4 K with an ArF excimer laser at 193 nm yielded new lines at 2045.1 and 968.0 cm(-1) that were depleted upon secondary photolysis at 308 nm. These lines are assigned to C=O stretching and mixed stretching modes of ONCO, based on results of 15N-, 13C-, and 18O-isotopic experiments and quantum-chemical calculations. These calculations using density-functional theory (B3LYP and PW91PW91/aug-cc-pVTZ) predict five stable isomers of NCO2: ONCO, NCOO, N-cyc-CO2, CNOO, and cyc-CNOO, listed in order of increasing energy. According to B3LYP calculations, ONCO has a trans configuration, with bond angles of angleONC approximately 136.3 degrees and angleNOC approximately 160.7 degrees. Calculated vibrational wave numbers, IR intensities, 15N-, 13C-, and 18O-isotopic shifts for ONCO agree satisfactorily with experimental results. ONCO was formed from reaction of CO with NO in its excited state.     

Electronic absorption and resonance Raman spectra of large linear carbon clusters isolated in solid argon

Neutral and anionic carbon clusters have been generated via a laser-induced graphite-based plasma and deposited in a solid argon matrix. Anionic clusters were formed from neutral clusters by using crossed electron/carbon cluster beams. Thermal annealing (to 36 K) resulted in the aggregation of the smaller carbon species, leading to the formation of long chain neutral and anionic clusters. Spectroscopic measurements in the ultraviolet, visible, near-infrared and infrared regions revealed a series of bands attributable to a homologous set of odd-numbered C5-C29 neutral clusters and even-numbered C6(-)-C36- anionic clusters. Good agreement is found for the band positions of carbon chains containing odd C15-C21 neutrals and even C6(-)-C22- anions, with species previously identified by Maier and coworkers using mass selection or laser vaporization, followed by neon matrix isolation. Resonance Raman frequencies for the neutral C17, C21 and C23 species are shown to be consistent with the above attributions. Density functional theory calculations agree well with the observed bands. It is found that certain low frequency Raman stretching frequencies decrease in a predictable way with increasing chain length. Comparison of the 0(0)0 absorption transitions of the even C18(-)-C36- anionic clusters with the 'unidentified' infrared (UIR) interstellar emission bands suggests that the electronic emission from specific long chain carbon anions may contribute to the some of the UIR bands.