Sum-Frequency Signals in 2D-Terahertz-Terahertz-Raman Spectroscopy

Abstract

We demonstrate that halogenated methane 2D-Terahertz Terahertz Raman (2D-TTR) spectra are determined by the complicated structure of the instrument response function (IRF) along ω 1 and by the molecular coherences along ω 2. Experimental improvements have helped increase the resolution and dynamic range of the measurements, including accurate THz pulse shape characterization. Sum-frequency exci

2D Raman–THz Spectroscopy of Binary CHBr3–MeOH Solvent Mixture

“…The most recent interpretation of the TTR signals by Blake and coworkers suggested that the observed signal stems from the instantaneous excitation of intramolecular vibrations through a two-photon absorption process by a pair of strong THz fields (sum-frequency excitation pathway). 23 This explanation is consistent with the interpretation of the THz-Kerr effect observed earlier for similar liquids. [24][25][26][27] Our RTT pulse sequence lacks the strong initial THz process required for that process.…”

2D Raman-THz spectroscopy of binary CHBr3-MeOH solvent mixture

“…The most recent interpretation of the TTR signals by Blake and coworkers suggested that the observed signal stems from the instantaneous excitation of intramolecular vi-brations through a two-photon absorption process by a pair of strong THz fields (sum-frequency excitation pathway). 23 This explanation is consistent with the interpretation of the THz-Kerr effect observed earlier for similar liquids. [24][25][26][27] Our RTT pulse sequence lacks the strong initial THz process required for that process.…”

“…[38][39][40][41] Furthermore, the double peak structure of the cross peak, or correspondingly, the beating of the time-domain data in the t 2 -direction, emphasize that the response is not instantaneous in the THz dimension in our RTT pulse sequence, unlike for the TTR pulse sequence. 23 The demonstrated sensitivity of 2D Raman-THz spectroscopy toward lowfrequency intra/intermolecular vibrational couplings can be utilized further to study structural characteristics of hydrogen bond network forming systems.…”

Equilibrium-nonequilibrium ring-polymer molecular dynamics for nonlinear spectroscopy

“…Two-dimensional vibrational spectroscopy is a versatile technique to study microscopic interactions at their natural, femtosecond time scales. 1 Recently, a series of hybrid spectroscopic experiments [2][3][4][5] involving mid-infrared, far-infrared (or terahertz), and visible (Raman) pulses have been developed to study electrical and mechanical anharmonicities, [6][7][8][9] structural heterogeneities of liquids, [10][11][12] and the couplings between intermolecular and intramolecular vibrational modes. 13,14 However, the interpretation of such spectra is still an open question and requires adequate simulation methods.…”