Spectroscopic determination of dipole-dipole interaction in solutions of trioctylammonium halides

Dimerization energies of trioctylammonium halides in carbon tetrachloride solution, associated as a result of dipole-dipole interaction, were calculated from the infrared absorption spectra. The values obtained were 5, 4, and 1.5 kcal/mole for the chloride, bromide, and iodide, respectively. The calculation showed that the dimers of these salts are contact dimers.     

Nonresonant and resonant mode-specific intermolecular vibrational energy transfers in electrolyte aqueous solutions

The donor/acceptor energy mismatch and vibrational coupling strength dependences of interionic vibrational energy transfer kinetics in electrolyte aqueous solutions were investigated with ultrafast multiple-dimensional vibrational spectroscopy. An analytical equation derived from the Fermi's Golden rule that correlates molecular structural parameters and vibrational energy transfer kinetics was found to be able to describe the intermolecular mode specific vibrational energy transfer. Under the assumption of the dipole-dipole approximation, the distance between anions in the aqueous solutions was obtained from the vibrational energy transfer measurements, confirmed with measurements on the corresponding crystalline samples. The result demonstrates that the mode-specific vibrational energy transfer method holds promise as an angstrom molecular ruler.     

Thermal lens spectroscopy in liquid argon solutions: (Deltav = 6) C-H vibrational overtone absorption of methane

A dual-beam thermal lens technique has been used to obtain the absorption spectrum of the (Deltav = 6) C-H stretch of liquid methane and methane in liquid argon solutions. The lowest concentration detected was 1 x 10(-3) (mole fraction) of CH(4) in liquid Ar with a continuous wave laser power of 20 mW. The thermal lens signal is linear with the mole fraction of methane up to 1 x 10(-2) but not for higher concentrations. Considering the system CH(4)-Ar as an ideal solution, the factors that contribute to the thermal lens signal were calculated as a function of the concentration of methane. A mechanism of energy transfer based on the gas-phase results could explain qualitatively the dependence of the magnitude of the signal on the mole fraction of methane.     

On the 3s-subshell excitation spectrum of argon

New results on the high resolution spectrum of ArI in the 3s-subshell excitation region are reported. The spectra are recorded in the second order of a 3-meter vacuum spectrograph and synchrotron radiation as the background source of continuum. The transitions: $$\begin{array}{*{20}c} {3s^2 3p^6 {}^1S_0 \to 3s({}^2S_{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} )3p^6 np} & {{}^1P_1 (4 \leqq n \leqq 25)} \\ \end{array} $$ have been extended to highern-values and more accurate level positions and binding energy of the 3s-subshell is achieved from the series limit. The spectrum has been analysed within the framework of non-relativistic Hartree-Fock and relativistic Hartree-Fock calculations. Intensity anomalies aroundn=9 have been atributed to an additional level arising from doubly excited state 3s ²3p ⁴4s4p.     

The vibrational spectrum of tetrafluoropropyne

The i.r. spectrum of gaseous tetrafluoropropyne has been measured from 4000 to 100 cm⁻¹, and all of the observed bands have been assigned. The e mode frequencies of the CF₃ group are similar to those of other CF₃CCX species, and even though the a₁ modes are less regular, the variations can be explained without changes in force constants other than those involving the CX bond. Several bands, particularly ν₁ and combinations with ν₁, show pronounced sequence structure due to excited levels of ν₁₀, the CCC skeletal bend.     

The vibrational spectrum of anisole

The infrared and Raman spectra of C₆H₅OCD₃, C₆D₅OCH₃ and C₆D₅OCD₃ have been recorded in the liquid state. Vibrational assignments have been made and values for most of the fundamental vibrations have been obtained and correlated with those of C₆H₅OCH₃. Studies of the ultraviolet absorption spectrum have provided gas-phase data on a number of totally symmetric modes.     

The effect of dipole-dipole interaction on zero-THz frequency polarisation

The effect of intramolecular dipole-dipole interaction on polarisation at frequencies from 0 – 10¹² Hz in dipolar media is investigated using a numerical solution of the Sturm-Liouville eigenvalue problem to which the governing Smoluchowski equation reduces. The results of Budó for the long-wavelength limit are extended to all frequencies up to the far infrared, where the predominant inertial effects are treated using a preliminary first-order correction. The numerical method of Pryce may be used to investigate much more realistic interaction potentials than the simple harmonic and cosine form considered by Budó. These simple forms are, however, sufficient to indicate that the integrated absorption intensity per molecule in the far infrared is very sensitive to dipole-dipole interaction and relative hydrodynamic drag on both interacting groups. Applications of the theory to the disordered solid and nematic phases are considered.     

Coriolis interaction in the raman spectrum of gaseous and liquid fluoroform

A study on the depolarization ratio of Raman spectrum in the region of the ν₂ and ν₅ fundamentals of CHF₃ shows clearly that both bands interact by strong Coriolis coupling. The effect is very obvious in the gas, but is also demonstrated for liquid CH F₃.     

The vibrational spectrum and structure of trifluorotrichlorodisiloxane

The vibrational spectrum of trifluorotrichlorodisiloxane (F₃SiOSiCl₃) is reported, analyzed and assigned in terms of a linear C_3v model, by comparison with that of structurally related hexachlorodisiloxane (Cl₃SiOSiCl₃). This is the first assignment of the vibrational spectrum for this molecule. The vibrational spectrum of Cl₃SiOSiCl₃ is assigned on the basis of a linear D_3d model, which is different from a bent C_2v model in the previous literature.     

The vibrational spectrum of dibutadieneiron carbonyl

A vibrational assignment has been proposed for (C₄H₆)₂Fe(CO). The internal butadiene modes show that there is very little interaction between the two C₄H₆ molecules, and that electronically it is very similar to C₄H₆ in (C₄H₆)Fe(CO)₃.     

The vibrational spectrum of allene-d1

The i.r. spectra of allene-d₁ in the vapour phase and as a crystalline solid at 90 K were recorded in the region 5000-200 cm⁻¹. Raman spectra, including semi-quantitative polarization data, of the vapour and of the neat liquid, contained in a sealed tube at ambient temperature, were obtained. The fundamental frequencies were assigned in good agreement with results from earlier normal coordinate calculations.     

Cis- and trans-3-hexene: infrared spectrum in liquid argon solution, ab initio calculations of equilibrium geometry, normal coordinate analysis, and vibrational assignments

The infrared spectra of cis-3-hexene and trans-3-hexene dissolved in liquid argon have been obtained at temperatures from 93 to 120 K. The absorptions were observed with a low-temperature cell and a Fourier transform infrared spectrophotometer. Ab initio molecular orbital calculations were performed to obtain the equilibrium geometry, vibrational frequencies, force fields, and infrared intensities. The calculations were done at the Hartree-Fock level using 6-31G basis set. The Cartesian force fields from ab initio calculations have been converted to the force field in symmetry coordinates. The scale factors of ab initio calculated force fields were determined. Normal coordinate calculations were performed using a scaled quantum mechanical (SQM) force field. Vibrational normal modes calculated for the lowest energy rotamers of cis- and trans-3-hexene have been assigned to infrared absorption bands observed in liquid argon solution. The assignments were based on calculated frequencies and potential energy distributions. The equilibrium geometries of the two lowest energy rotamers (symmetry C₂ and C_s) of cis-3-hexene and of the three lowest energy rotamers (symmetry C_i, C₂, and C₁) of trans-3-hexene were calculated. Variable temperature studies of the infrared spectrum of cis- and trans-3-hexenes dissolved in liquid argon were done to obtain the ΔH of conversion between the rotamers C₂ and C_s of cis-3-hexene and between the rotamers C_i, C₂, and C₁ of trans-3-hexene.     

按非刚性转子模型计算NF3和环氧乙烷的光谱熵

NF_3和环氧乙烷(C_2H_4O)作为推进剂,曾由Sundaram按刚性转子-谐振子模型计算了其光谱熵.但由于忽略了离心力的影响,必然致使计算结果偏低(尤其在高温下).本文按Kivelson等给出的离心力校正参数τ值与离心力伸长常数D_J、D_(JK)和D_K间的关系式,由微波谱给出的数据计算了C_2H_4O的离心伸长常数(表1).改按非刚性转子—谐振子模型,采用直接加和法重新精确计算转动、振动配分函数,进而在100～2000K范围内计算了NF_3和C_2H_4O的光谱熵(表2).比较了所得结果与Sundaram的计算值     

Infrared spectrum of the CH3OCH2 radical in solid argon

The methoxymethyl radical, CH(3)OCH(2), is prepared via hydrogen photodissociation from dimethyl ether during codeposition of CH(3)OCH(3) in excess argon at 4 K with laser-excited metal plume radiation. The spectrum of this radical is characterized by four infrared absorptions at 1468.1, 1253.9, 1226.6, and 944.4 cm(-1), which are assigned by deuterium substitution as well as frequency and intensity calculations using density functional theory. The O-CH(2) bond length is calculated to be 0.07 ? shorter than the CH(3)-O bond due to additional π bonding interactions. In the matrix near-UV irradiation destroys the CH(3)OCH(2) radical with the formation of HCO radical and CH(4), which is different from the decomposition mechanism of CH(3)OCH(2) radical to H(2)CO and CH(3) radical proposed for the gas phase process.     

The vibrational spectrum and conformations of allyl chloride

Infrared and Raman spectra are reported for allyl chloride in vapour and liquid phases and also by matrix isolation in argon and nitrogen. Assignments are made in terms of a predominant low energy gauche form with a smaller amount of high energy cis form in all phases.