Infrared dephasing and librational motion in liquid methyl iodide

Rothschild, Walter G.; Soussen-Jacob, J.; Bessiere, J.; Vincent‐Geisse, J.

doi:10.1063/1.446130

Cited by 25 publications

(8 citation statements)

References 26 publications

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“…5͑d͔͒ or the expression for R ͑5͒ ͑ 1 , 2 ͒ in Appendix B, in which the states are explicitly shown. This term is proportional to the inverse of the oscillation frequency squared, while the pure two-quantum one is inversely proportional to 3 . Note that these are stronger frequency dependencies than that of the leading term of the third-order nuclear response ͑ϳ Ϫ1 ͒.…”

Section: ͑24͒mentioning

confidence: 99%

“…Traditionally, the dynamics of atomic and molecular liquids are studied by far-infrared ͑FIR͒ absorption spectroscopy 3,4 or by Rayleigh-Raman scattering, [5][6][7][8] that measure the Fourier transform of the one-time correlation function of the dipole moment and polarizability, respectively. In the thermal range below 300 cm Ϫ1 , the fluctuations in these bulk properties are associated with the same lowfrequency intermolecular motions.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Time resolved four- and six-wave mixing in liquids. I. Theory

Steffen¹,

Fourkas

Duppen

1996

The Journal of Chemical Physics

155

154

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Low-frequency intermolecular dynamics in liquids is studied by ultrafast four-and six-wave mixing. The theory of these nonlinear optical processes is given for electronically nonresonant optical interactions up to fifth order in the electric field. The Born-Oppenheimer approximation is used to separate the motional part of the response functions from coordinate independent electronic hyperpolarizabilities. A large variety of experiments, involving far-infrared absorption, ordinary Rayleigh-Raman or hyper Rayleigh-Raman scattering is covered by this theory. The response in nonresonant six-wave mixing comprises four dynamically different processes. It is shown that one of the terms contains information on the time scale͑s͒ of intermolecular dynamics, that is not available from lower-order nonresonant experiments. For instance, homogenous and inhomogeneous contributions to line broadening can be distinguished. The optical response of harmonic nuclear motion is calculated for nonlinear coordinate dependence of the polarizabilities. Results for level-dependent and level-independent damping of the motion are compared. It is shown that level-dependent damping destroys the interference between different quantum mechanical pathways, yielding an extra contribution to the fifth-order response that has not been discussed before. When two or more nuclear modes determine the optical response, their relative contributions to the four-and six-wave mixing signals are in general different. These contributions are determined by the coordinate dependence of the electronic polarizability, which is usually not fully known. Model calculations are presented for the dynamic parameters of liquid CS 2. The theory of this paper will be employed in Part II, to analyze experimental results on femtosecond four-and six-wave mixing.

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Section: ͑24͒mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Time resolved four- and six-wave mixing in liquids. I. Theory

Steffen¹,

Fourkas

Duppen

1996

The Journal of Chemical Physics

155

154

View full text Add to dashboard Cite

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“…On the experimental side, manifestations of cage effects were found by different means, for example from careful analysis of infrared 12 and Raman 13 band shapes. Also lower frequency spectroscopies like EPR can detect them when the frequency dependence of spectral densities is analyzed, showing both higher frequency and lower frequency effects.…”

Section: Introductionmentioning

confidence: 99%

Rotational dynamics of axially symmetric solutes in isotropic liquids. I. A collective cage description from molecular dynamics simulations

Polimeno

Moro

Freed

1995

The Journal of Chemical Physics

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An operational definition of collective cage variables previously introduced for liquid argon is extended, via a molecular dynamics study, to the rotational properties of axially symmetric molecules. Quantitative measures of the static and dynamic cage properties are extracted for liquid Cl 2 near the triple point. The collective cage variables are well described by the potential acting on an arbitrary molecule ͑i.e. solute͒ for a fixed configuration of the other molecules ͑i.e. solvent͒. A dynamic separability of the solute orientation relative to the cage potential and of the relative solute displacement is justified in part by the faster relaxation found for the latter. Large and persistent orientational cage potentials ͑ϳ15-20 k B T) lead to substantial alignment of the solute in the cage with an average local order parameter of 0.87. The reorientational correlation times for the cage are consistent with axially symmetric Brownian motion. The reorientational correlation times for the solute are nearly equal to the equivalent ones of the cage, consistent with the strong coupling of solute within its cage which leads to a collective reorientation of solute and cage ͑e.g. cage (2) ϭ1.4 ps, and solute (2) ϭ1.2 ps͒. Solute librations within the cage are much faster (libr (2) ϭ0.12 ps͒ and are comparable to the relaxation of the relative solute displacements (r ϭ0.15 ps͒. The solute angular momentum exhibits the fastest correlation time (J ϭ0.06 ps͒. While the orientational cage potential shows rapidly and slowly relaxing components (f ϭ0.14 ps and s ϭ2.87 ps, respectively͒, its dominant portion shows a very long persistence.

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“…Data fit of the theory for the polycrystal is straightforward; it has been described previously (12).…”

Section: Methodsmentioning

confidence: 99%

“…Without attempting to define any specijic modulation process for a glass, this, at least, gives a useful hint to the effect that the dynamics of the glassy quinoline which lead to a modulation event at the active oscillator site are far removed from a chain of uncorrelated random steps ( a = 1, h(t) = constant). Equation [12] shows that the later is the time instant of observation, the smaller is the rate h(t) = f(t)/F(t); in other words, the later is t, the smaller is the probability density f(t) that the autocorrelation of the random oscillator frequency w '(t) changes at t relative to the probability F(t) (survivor probability (24)) that it has not yet changed at times ti 5 t. The effect of the sets of a , T (ps) = 1.00,3; 0.60,7; 0.30,40 on h(t) are shown in Fig. 2, which also contains the (near-identical) associated F(t): the increased drop of h(ij with decreasing a is evident.…”

Section: Glassy Statementioning

confidence: 99%

Models of picosecond-scale mobilities in glassy and polycrystalline quinoline

Rothschild¹

1988

Can. J. Chem.

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This paper is dedicated to Professor J. A. Morrison WALTER G. ROTHSCHILD. Can. J. Chem. 66,725 (1988). The observed inhomogeneous band broadening of the 1033-cm-' ir C-H in-plane deformation fundamental of quinoline in a glassy state and a polycrystal at 115 K was related to the theoretical concepts of the underlying vibrational T2 processes. The motional narrowing model that fits best the spectral data and reflects the particular physical nature of the locally-ordered glass is the recently introduced stretched ("extended", "fractional") exponential exp [-(t/~)"]. Extension of the model to shorter time regimes is discussed. The modulation model which simulates the corresponding spectral data and describes the longer-range order of the polycrystal is the damped oscillator exp (

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Infrared dephasing and librational motion in liquid methyl iodide

Cited by 25 publications

References 26 publications

Time resolved four- and six-wave mixing in liquids. I. Theory

Time resolved four- and six-wave mixing in liquids. I. Theory

Rotational dynamics of axially symmetric solutes in isotropic liquids. I. A collective cage description from molecular dynamics simulations

Models of picosecond-scale mobilities in glassy and polycrystalline quinoline

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