Charles A. Frenzel

Investigations of the Raman and Infrared Spectra of Thiophosgene and Polymeric Species

The Raman and infrared spectra of thiophosgene and its dimer have been reinvestigated and assignments based on new data and a normal coordinate analysis of the monomer are presented. The spectra obtained in gas, liquid, and solid phases are compared and two polymeric species and their spectra are discussed. A description of the fundamentals of thiophosgene is presented in terms of atom displacements, potential energy distributions, and Coriolis coupling coefficients. The transferability of the valence force field between thiophosgene and phosgene is demonstrated.

New Measurements of the Infrared and the Raman Spectrum of S2Cl2

The Raman spectrum of S2Cl2 has been excited with a 6‐mW He–Ne laser, 6328 A, and new depolarization ratios of the Raman bands have been obtained. The Raman band at 449 cm−1 previously reported by earlier workers is shown to be two bands corresponding to two fundamentals, one of Type A and another Type of B, at 446 cm−1 and 434 cm−1, respectively. The Raman band at 102 cm−1 corresponding to the torsional mode is found to be polarized in disagreement with earlier investigations; the torsional mode is far‐infrared active at 106 cm−1. Three infrared‐active fundamentals and six overtones were observed in the 3000–400 cm−1 region. One of these overtones at 1340 cm−1 has not been reported previously. One Raman overtone band and one Raman combination band have been observed at 858 cm−1 and 647 cm−1, respectively. The Raman and infrared data have been correlated with the right‐angle configuration of C2 symmetry, and thermodynamic properties have been calculated for the liquid state using the harmonic‐oscillator a...

New measurements of the Raman and the IR spectrum of K2Cr2O7

Abstract Raman spectra of a monocrystal of K 2 Cr 2 O 7 and a water solution of K 2 Cr 2 O 7 have been excited with a 6-mW He-Ne laser, 6328A, and new bands and bands splittings have been observed. The far- ir spectrum of the crystal powder in a polyethylene matrix has been obtained from 400–40 cm −1 and six new bands are recorded. In the monocrystal three new Raman bands are seen at 130 cm −1 , 564 cm −1 and 744 cm −1 . The Raman bands observed in the monocrystal correlate well with the earlier ir data up to 556 cm −1 .

On a Vibrational Analysis of S2Br2 and S2Cl2

Recent investigations of the Raman and infrared spectra of S2Br2 and S2Cl2 have reported new polarization data and the observation of previously unreported fundamentals. A normal coordinate analysis investigates the transferability of the valence force field for these molecules, and the results of these calculations are reported in terms of potential‐energy distributions, vibrational mean amplitudes, Cartesian atom displacements, and Coriolis coupling coefficients. The respective spectra are discussed in light of these data, and a value for the S—S force constant is reported.

Reinvestigation of the Raman spectrum of benzophenone using a He-Ne laser

Abstract The Raman spectrum of powdered benzophenone, molten benzophenone, and a solution of benzophenone in methyl alcohol was excited with a He-Ne laser, 6328 A. Thirty-two Raman bands have been observed for the powdered sample, fifteen of which were not reported previously for the powdered sample. Three new bands are observed at 107, 172, and 366 cm −1 in the case of molten benzophenone. Only one carbonyl frequency at 1653 cm −1 is known to be present from this work, in contradiction to two carbonyl frequencies at 1660 and 1708 cm −1 in molten benzophenone, as reported by previous workers. Nineteen Raman bands are reported in the case of a methyl-alcohol solution of benzophenone, fifteen of which are polarized, three depolarized and one weakly polarized. The intensity of several of the Raman bands suggests that this molecule may exhibit stimulated Raman scattering in the solid state.

New Measurements of the Raman and the Far‐Infrared Spectrum of S2Br2

The Raman spectrum of S2Br2 has been excited with a 6‐mW He–Ne laser operating at 6328 A, and new depolarization ratios of the Raman bands have been obtained. The Raman band at 68 cm−1 corresponding to the torsional mode is found to be polarized in disagreement with an earlier Raman investigation; the torsional mode is far‐infrared active at 70 cm−1. The Raman band at 534 cm−1 is found to be polarized and of type A in contrast to earlier work in which this band was found to be depolarized and of type B. The Raman band at 304 cm−1 is found to be depolarized and of type B whereas in an earlier investigation the band was reported as polarized and of type A. The new Raman and infrared data have been correlated with the right‐angle configuration of C2 symmetry and new assignments have been made. Six coincident Raman‐ and infrared‐active fundamentals are now known from this work and the work of others.

Raman Spectrum of a Crystalline Polyethylene

New data have been obtained for the Raman spectrum of a crystalline polyethylene and a detailed examination of the Raman spectrum is presented from 40 to 3000 cm−1. Raman bands correlating with neutron‐scattering data are observed. The region of rotary and translational crystalline bands has been searched for bands correlating with calculated infrared‐active crystal lattice modes.

Slit-Function Corrections Applied to Laser-Excited Raman Bands of Liquids

The use of small spectral slitwidths complicates Raman intensity measurements of laser-excited spectra. The nature of the slit-function correction in medium-resolution laser-Raman instruments is discussed and some effects of asymmetric slit functions on asymmetric and symmetric Raman bands are explored. Corrections to bandwidth and band shape for nonideal slit functions are obtained from the concept of an intermediate standard which represents the pure slit function at some limiting spectral slitwidth. The corrections are applied to the contours of the Raman bands of CCl4 at 458 cm−1 and CH3OH at 1028 cm−1, and the corrected contour of the 1028-cm−1 band is compared to that obtained for the same band on a high-resolution laser-Raman spectrometer. A codification of Raman band shapes by means of two shape parameters is discussed.

The Bicarbonate Ion in Solid Solution in Alkali Halides: An Optical Filter at 10.6 μm

When single impurity ions go into solid solution in alkali halide crystals, very narrow absorption bands appear in the infrared spectra of these materials. These narrow bands arise from the isolation of the individual impurity ions in the crystal lattice. Such bands have a bandwidth of 2 to 6 cm−1 at room temperature and 0.5 to 2.0 cm−1 at liquid nitrogen temperature. The frequency of the band shifts 2 to 4 cm−1 higher at liquid nitrogen temperature.

Detection of salts of 2,4-D in aqueous solution by laser Raman spectroscopy

Abstract Laser Raman spectroscopy is used to detect a salt of a herbicide, 2,4-dichlorophenoxy acetic acid, in water solution at concentrations as low as 500 ppm. The Raman spectrum of the powder is substantially different from the spectrum of the pollutant in aqueous solution. The spectrum of the potassium and sodium salts are the same for the powder or aqueous solution. Five strong bands exist in aqueous solution, and four of these bands are detectable at concentrations as low as 500 ppm. A plausible assignment to group frequencies for some of the Raman bands is given. All spectra were excited with a 50 mW He-Ne gas laser at 6328 A. Lower concentrations should be detectable with a more powerful laser at a higher frequency because: (1) the intensity of the scattered radiation is proportional to the product of the intensity of the electric field perturbing the molecule and the fourth power of the scattered frequency; (2) the attenuation coefficient of water is less; (3) the photocathode used is more efficient at higher frequencies and (4) the monochromator grating used is blazed at 5000 A. The resonance Raman effect is discussed as a possible method for the detection and identification of small optimal concentrations of pollutant in water.