Analysis of Intermolecular Coordinate Contributions to Third-Order Ultrafast Spectroscopy of Liquids in the Harmonic Oscillator Limit

Abstract

The apparently-multicomponent subpicosecond intermolecular dynamics of carbon disulfide liquid are addressed in a unified manner in terms of an inhomogeneously broadened quantum mechanical harmonic oscillator model for a single vibrational coordinate. For an inhomogeneously broadened (Gaussian) distribution of oscillators, the model predicts naturally the bimodal character of the subpicosecond intermolecular dynamics of carbon disulfide liquid, and also the spectral evolution effects (spectral narrowing and saturation) that are observed for solutions of carbon disulfide in weakly interacting alkane solvents. The unique dynamical signature of these low-frequency vibrational coordinates is determined largely by the physical constraints on the coordinates (near equality of oscillator frequency, dephasing frequency, and inhomogeneous bandwidth), such that constructive and destructive interference effects play a dominant role in shaping the experimental observable.

Cation and anion substitution effects on the ultrafast dynamics of interionic interaction in imidazolium based ionic liquids

“…6 ] well agrees with the previously reported data [23,24]. As shown in Figure 1, we observed two-period oscillations in the fs-OHD-RIKES signal of [31][32][33][34][35][36][37]. As for the ILs systems, researchers generally converted their time domain fs-OHD-RIKES signals into frequency domain through FFT theorem, and then decomposed the fs-OHD-RIKES FFT spectra with either a summation of one Ohmic or BL function and several antisymmetrized Gaussian functions or a summation of several BOs [18][19][20][21][22][23][24][25][26].…”

“…The BO model has been successfully employed to analyze the fs-OHD-RIKES signal in time domain in simple molecular liquid [31][32][33][34][35][36][37]. Here, we applied the BO model into the ILs system.…”

Intermolecular Dynamics and Structure of Carbon Disulfide in Isoviscous Alkane Solutions: An Optical Kerr Effect Study

“…25 Since the intermolecular spectrum cannot extend below zero frequency, intermolecular spectra are necessarily asymmetric and do not reflect the spectral distribution of any underlying inhomogeneity directly. The intermolecular portion of the response function is given by 21 where g(ω) is the inhomogeneous distribution of frequencies and r nuc,inter (3) (ω,t) is a frequency-dependent response function. We will consider a recently proposed model for this response function.…”

“…We will consider a recently proposed model for this response function. 21 In this model, the oscillators are not allowed to overdamp, i.e., For the inhomogeneous distribution function we chose to use an antisymmetrized Gaussian,…”

The Effect of Induced Multipoles on the Fifth-order Raman Response

“…Therefore the dynamics of liquids have been studied extensively experimentally applying, for example, third-order time resolved Raman techniques. [1][2][3][4][5][6] In the last decade substantial efforts have been made in order to measure, 7-15 model [16][17][18][19][20][21][22][23] and calculate [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41] the fifth-order Raman response suggested by Tanimura and Mukamel. 16 Spectroscopies relying on this response should be able to distinguish between different relaxation mechanisms, which the lower order techniques cannot.…”