The Raman spectrum of propynal

The Raman spectrum of propynal as a vapour and dissolved in various solvents were recorded. These data and the observed polarization measurements were in accordance with the fundamental frequencies assigned to the ground state of this molecule. The vibrational modes of propynal were compared with those previously reported for the halopropynals.     

The infrared and Raman spectra of carbonyl diisocyanate

The infrared and Raman spectra of carbonyl diisocyanate have been recorded. Vibrational assignments have been made on the basis that two planar conformations are present both in the liquid and vapour phases: cis—cis and cis—trans. Simple normal coordinate calculations have been used to confirm the assignments.     

The resonance Raman spectrum of azulene

Excitation profiles have been measured for three Raman lines of azulene in CS₂ solution in the spectral range of the visible absorption system, viz. 665—570 nm. The results are unexpected in as much as the excitation profiles do not exhibit maxima at or near the absorption peaks. The results are interpreted on the basis of contributions to the A-term by other modes than the one studied in the Raman effect. These terms give rise to interferences which lower the excitation profile in some regions while causing maxima at other frequencies.     

The far infrared spectrum of nitroethane

The far infrared spectrum of nitroethane measured by Founer spectroscopy in the 8-60 cm^?1 is presented and interpreted in terms of a rigid frame-rigid top model for free internal rotation group. Ratational-internal rotational energy levels and absolute absorption intensities are calculated to first order for an optimal choice of molecule-fixed axes. The computed absorption based on a permanent dipole moment of 3.4 debye along the NC direction is in excellent agreement with the observed band.     

The infrared and Raman spectra of guanidinium salts

The i.r. and Raman spectra of guanidinium chloride, guanidinium perchlorate, and the deuterated derivatives of these salts, have been determined as solids and in solutions.     

The infrared and Raman spectra of pyromellitic dianhydride

The infrared and Raman spectra of solid state samples of pyromellitic dianhydride have been measured. The infrared—Raman mutual exclusion rule has been observed and the frequencies have been tentatively assigned on the basis of D_2h symmetry. The values of the CO and skeletal ring stretching frequencies have been interpreted in terms of a conjugated π-system.     

The infrared spectrum of californium-249

The Cf-249 spectrum between 3700 and 12,000 cm^?1 has been recorded. The strongest 90 lines are listed.     

The infrared and Raman spectra of trans- and cis-tetrachloro-tetramethylbicyclopropylidene

The title compounds trans- and cis-2,2,2',2'-tetrachloro-3,3,3',3'-tetramethyl-bicyclopopylidene were synthesized, and their infrared and Raman spectra were recorded. Non-coincidence between the IR and Raman bands of the trans compound suggested C(2h) symmetry and a planar ring system. In the cis compound most of the IR and Raman bands coincided and a C(2v) symmetry seems likely. The exocyclic CC double bond gave rise to a medium/weak Raman band at 1,847 cm(-1) in the trans compound. In the cis derivative IR and Raman bands both at 1,825 cm(-1) were observed. From similarities with related molecules, the ring breathing, the antisymmetric ring stretch, the CCl(2) out-of-phase and in-phase stretch and the out-of-plane ring bending modes have been tentatively assigned for the trans and cis compounds.     

The infrared and Raman spectra of octachloro- and octabromocyclotetrasilane

The infrared and Raman spectra of cyclo-Si₄Cl₈ and cyclo-Si₄Br₈ have been measured and assigned. The selection rules indicate that the Si₄ ring is not planar. A normalcoordinate analysis (NCA) has been performed. The SiSi stretching-force constants are calculated to be 1.75–1.5·10² Nm^?1 and are lower than in the corresponding perhalogenated five- and six-membered rings. The SiCl and SiBr force constants seem to be somewhat higher (2.7–2.35·10² Nm^?1).     

The matrix infrared spectrum of PN and SiS

Gaseous PN and SiS have been prepared at high temperatures from P₃N₅ and from CS₂ + Si respectively, and the species have been trapped in krypton matrices at 10°K. Infrared studies using P¹⁴N and P¹⁵N showed matrix isolated PN monomer and its aggregation to P₃N₃, a molecule isostructural with Si₃O₃ with D_3h symmetry; P₂N₂ was not detected. Both SiS and Si₂S₂ were detected by i.r. in the SiS/Kr matrix but no higher polymers could be characterised. The molecular parameters of SiS and Si₂S₂ calculated from the infrared data are in line with those for other matrix isolated Group IV chalcogenides.     

The laser Raman and infrared spectra of crystalline dibenzyl

The Raman spectrum of crystalline dibenzyl has been excited with a 50-mw He-Ne laser (6328 Å) and thirty one Raman bands have been recorded. The far infrared spec trum which reveals six absorptions in the 10–270 cm⁻¹ region and the infrared spectrum from 300–3200 cm⁻¹ have been observed, and correlations with the Raman frequencies have been established. Assignments of some of the characteristic frequencies have been made, and the implications of the data regarding the geometry of the molecule are discussed.     

The identification of fibers by infrared and Raman microspectroscopy

The application of Raman and infrared microspectroscopy to fiber identification has been investigated. Natural and synthetic fibers, both organic and inorganic in nature, can be rapidly characterized by these techniques. In general, it has been found that infrared microspectroscopy offers a nonsubjective method of fiber identification that is quicker, easier, and occasionally, more selective than classical methods. Raman microspectroscopy has also been proven useful for these analyses. It provides low-frequency information, requires virtually no sample preparation, and supplies data complementary to that furnished by infrared microspectroscopy. In many cases one may use these methods for a quick differentiation of fibers of the same type which have undergone different chemical treatments.     

The Fourier Transform Raman and infrared spectra of naphthazarin

The FT Raman spectra of the three naphthazarin polymorphs have been recorded for the first time and compared with the FTIR spectra of the polymorphs and of naphthazarin with deuterated hydroxyl groups. It is possible to distinguish between the polymorphs, to deduce that the room temperature static symmetry point group of naphthazarin is C_2v, to assign the ν(CH), σ(OH), γ(OH) vibrations and to confirm the absence of the ν(OH) mode.     

The Raman spectrum of predissociating nitrogen dioxide

The Raman spectrum of NO₂ excited at 355 nm is found to be dominated by bands containing up to six quanta of the bending vibration and four quanta of the symmetric stretch, with an almost complete absence of bands containing asymmetric stretch quanta. These results are interpreted within a time-dependent view to provide insight into the predissociation dynamics of NO₂.     

The Raman spectrum of hexamethylbenzene single crystal

A set of polarized Raman spectra obtained from suitable hexamethylbenzene single crystals at room temperature is presented. All the observed frequencies are attributed to intramolecular vibrations or lattice modes on the basis of clear polarization data.     

The resonance Raman spectrum of ultramarine blue

The resonance Raman spectrum of ultramarine blue has been observed by the use of 457.9, 488.0, 514.5, 568.2 and 647.1 nm excitation. With 457.9 nm excitation three progressions are observed; comparison of the results with earlier data from sulphur-doped alkali halide crystals indicates that ultramarine blue contains the S₂^? as well as the S₃^? anion.     

The far infrared spectrum of pyridine n-oxide

The two lowest internal modes of pyridine N-oxide and three of its lattice oscillations in the solid state at room temperature are reported for the first time on the basis of careful far infrared investigations from 33 to 525 cm^?1.