Raman spectra of molten MgCl2, MgCl2–KCl, and MgCl2–2KCl were recorded, at 730°, 525°, and 475°C, respectively, using a Cary 81 Raman spectrophotometer. Liquid MgCl2 exhibits three Raman lines with frequencies 269, 214, and 142 cm−1, which are explainable on the basis of the presence of MgCl64— ions with octahedral configuration. Liquid MgCl2–KCl exhibits four Raman lines with frequencies 451, 250, 208, and 158 cm−1; and their polarization characteristics indicate the existence of MgCl3− ions with pyramidal configuration C3v. The Raman spectrum of liquid MgCl2–2KCl is almost similar to that of liquid MgCl2–KCl. Force constants for the various Mg–Cl ionic species were calculated using generalized valence forces.
The Raman spectra of AgN03-CH3CN solutions (0.01 to 9 mol/1.) have been investigated with He-Ne and Ar+ ion lasers as excitation sources. In the symmetrical N03~stretching frequency region, two frequencies, 1036 and 1041 cm-1, are observed. The concentration dependence of the relative intensities of these two frequencies is examined from the viewpoint of ion-ion interactions. The band contours of C=N and C-C stretching frequencies of CH3CN have also been examined. As AgNG3 is added, these bands resolve into two components and the variations of their relative intensities with concentration are understood, largely, through marked solvation interaction in the solute-solvent system.
to 139.184.30.132. Redistribution subject to AIP license or copyright; see http://jcp.aip.org/about/rights_and_permissions 676 SERGIO PISSANETZKY computed values are of the order AlA2= 0.02 for both Ichishima's first and second lines, smaller by a factor of 5 than the experimental value. The fact that the quadrupole transitions are induced by the second torsional frequency at room temperature and by the first at 22°K, and that at nOK the computed transition probabilities for each torsional frequency are too small, suggests the possibility that at this temperature both frequencies contribute to the relaxation. In fact, by simply adding both values of Al and both values of A2 the following value is obtained: A l A 2 =0.095, very nearly the experimental value. This means that nOK is THE JOURNAL OF CHEMICAL PHYSICS a transition temperature, because the relaxation is produced by the lower-frequency torsional oscillation alone at 22°K and by the higher one, also alone, at 300°K.The substitution of (1) and (2) in 1/2TI = W I + W 2 gives a quadratic equation for Ta which yields two values, one of them corresponding to a W 2 /W I too large and the other to a W 2 /W I too small. But this is not representative, because Ta is very sensitive to variations in Al and A2, which, in turn, depend on insufficiently precise experimental values. Of course, all these considerations require a comparison with more experimental evidence than now exists.The Raman spectra of AlCh·KCl (solid and liquid) and AlC!a·NaCI (liquid) were recorded using a Cary 81 Raman spectrophotometer. Both solid and liquid AlC!a·KCl exhibit nine Raman lines. For liquid AlCla·NaCl, only four Raman lines were observed. Polarization measurements indicate the existence of the complex species AlCL.-, with a distorted tetrahedral structure (C2v) in solid and liquid AlCla·KCl and a regular tetrahedral structure (Td) in AlC!a·NaCI. The force constants for AlCl.-ion were calculated using a generalized valence force.
The laser Raman spectra of AgNO3 and TlNO3 have been investigated from the room temperature to an upper limit of about 25°C above their respective melting points (AgNO3, mp 210°C; TlNO3, mp 208°C). Striking results are the observation of the asymmetric shape in the totally symmetric N–O stretching mode (∼1046 cm−1) and the spectral changes accompanying the phase transitions in these solids. While various reasons can be advanced for the asymmetry of the 1046-cm−1 band, the explanation based on the coupling of vibrational modes of adjacent NO3− groups seems most reasonable.
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