S. R. Polo

Vibration—Rotation Interaction in Polyatomic Molecules. I. The Zeta Matrices

Some properties of the zeta matrices which simplify the analytical treatment of vibration‐rotation interaction are given. Methods of obtaining relationships among the zeta elements which depend only on the atomic masses and geometry of the molecule are outlined and some examples are discussed. Symmetry arguments are introduced to simplify the results further.

Infrared Intensities in Liquid and Gas Phases

It is shown that Debyes and Onsagers theories of dielectric polarization lead to the same expression for the relation between the intensities of an infrared absorption band in the liquid and in the gas phases.

Vibration—Rotation Interaction in Polyatomic Molecules. II. The Determination of Coriolis Coupling Coefficients

A general method for the analytical treatment of vibration‐rotation interaction in polyatomic molecules is presented. The method is especially adapted to carry out the calculation of the Coriolis coupling coefficients along with the normal coordinate treatment in terms of any chosen set of internal coordinates. The relations existing among the ζ elements and the potential constants are established in a general and convenient form. Particular attention is given to symmetric top molecules, and the effect of vibration‐rotation interaction on band structure is discussed. Approximate methods for the calculation of zeta values are considered also.

Infrared Spectra and Molecular Structures of SiH3F, SiH3Cl, and SiH3Br

The structure of the e‐type fundamentals of SiH3F, SiH3Cl, and SiH3Br has been resolved and analyzed. The values of the small amount of inertia thus obtained has been combined with microwave measurements to yield the dimensions of the SiH3 group in these molecules. It is shown that the differences in the structure of the SiH3 group are probably within experimental error. Several revisions have been made in the vibrational assignments for SiH3F and SiH3Cl.

The Infrared Spectra of NF3 and PF3

The infrared spectra of NF3 and PF3 have been investigated with a prism instrument in the range 250 cm−1 to 5000 cm−1. The fundamental frequencies are for NF3, ν1(A1)=1032 cm−1, ν2(A1)=647 cm−1, ν3(E)=905 cm−1, and ν4(E)=493 cm−1; and for PF3, ν1(A1)=892 cm−1, ν2(A1)=487 cm−1, ν3(E)=860 cm−1, and ν4(E)=344 cm−1. Force constants as well as thermodynamic functions are calculated for both molecules.

Infrared Spectrum of S16O18O and the Potential Constants of SO2

An investigation of the infrared spectrum of S16O18O results in the following frequency assignment: ν1=1122±1 cm−1,  ν2=506.8±0.5 cm−1,  ν3=1341±0.5 cm−1. These data combined with the fundamental frequencies of S16O2 have been used to calculate the potential constants for sulfur dioxide. These are fd=10.02,  fdd=0.03,  1dfdα=0.20,  1d2fα=0.793.

The Infrared Spectrum of CF3D

CF3D was prepared in high purity and its infrared spectrum investigated. The fundamental frequencies are ν1(a1)=2257 cm−1,ν2(a1)=1111 cm−1,ν3(a1)=693 cm−1,ν4(e)=1210 cm−1,ν5(e)= 977 cm−1,ν6(e)=502 cm−1. Thermodynamic functions have been calculated with the usual assumptions.

Substituted Methanes. XXVI. Raman and Infrared Spectral Data, Assignments, Potential Constants, and Thermodynamic Properties for CHBrCl2 and CDBrCl2

Raman displacements, semiquantitative relative intensities, and quantitative depolarization factors for liquid bromodichloromethane and deuterobromodichloromethane, as well as infrared wave numbers and percent transmission curves for both the liquid and gas in the region 400—4000K (K = kaysers = cm—1), were obtained and compared with previous data. Assignments were made for both molecules and a reasonable set of potential constants was determined by use of Wilsons FG matrix method. The heat content, free energy, entropy, and heat capacity were calculated for 12 temperatures from 100° to 1000°K.

Rotational Constants of SiH3D

The analysis of the rotational structure of the Si — D stretching fundamental yields the following values: B′′=2.11±0.01 cm−1,  B′′−B′=0.019 cm−1,  ν0=1594.4±0.1 cm−1. The value of the Si — H distance obtained under the assumption that it remains unchanged by isotopic substitution is dSi−H=1.477±0.003 A.