Single beam low frequency 2D Raman spectroscopy

Abstract

Low frequency Raman spectroscopy resolves the slow vibrations resulting from collective motions of molecular structures. This frequency region is extremely challenging to access via other multidimensional methods such as 2D-IR. In this paper, we describe a new scheme which measures 2D Raman spectra in the low frequency regime. We separate the pulse into a spectrally shaped pump and a transform-limited probe, which can be distinguished by their polarization states. Low frequency 2D Raman spectra in liquid tetrabromoethane are presented, revealing coupling dynamics at frequencies as low as 115 cm−1. The experimental results are supported by numerical simulations which replicate the key features of the measurement. This method opens the door for the deeper exploration of vibrational energy surfaces in complex molecular structures.

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

“…4,5 Recently, a single pulse 2D Raman technique developed by Silberberg and coworkers was implemented to overcome the most significant experimental obstacle in the form of parasitic low-order cascading process 6 and demonstrated the ability to measure intramolecular coupling of simple halogenated liquids. 7 Steady progress in the generation and manipulation of strong THz fields 8 stimulated the development of alternative spectroscopic path toward lowfrequency multidimensional spectroscopy -third-order 2D THz spectroscopy 9 which probes multipoint correlation function of the nuclear dipole moment of lowfrequency transitions. 2D THz spectroscopy was successfully realized on molecules in a gas phase 10,11 and semiconductor solids 12 , however, the still rather limited available energies and bandwidth of THz pulses, and the experimental limitation in generation and recombination of multiple THz pulses, have not allowed yet the realization of such experiments in liquids, where transition dipoles of the low-frequency modes are extremely small.…”

Full molecular dynamics simulations of molecular liquids for single-beam spectrally controlled two-dimensional Raman spectroscopy

“…In contrast to the signals used in conventional 1D and 2D Raman spectroscopy, which are created using ultrashort Raman pulses, those of SBSC Raman spectroscopy are, in principle, frequency-domain measurements, although in a real-time description of these measurements, they can be regarded as being composed of short pulse trains. [48][49][50][51][52] These measurements rely on the vibrational excitations that are created by a pulse sequence whose time period corresponds to a vibrational mode. Gaussian electric field, G(ω)…”

“…Therefore, a new SBSC setup that consists of a spectrally shaped pump and a transform-limited probe has been developed. 52 The electric field is now defined as…”

“…Although the original pulse design for such measurements had difficulty in separating the contributions of the fifth-and third-order polarizations, a recently introduced pulse design overcomes this problem and opens up a new possibility for SBSC 2D Raman spectroscopy. 52 Thus, we are now able to investigate complex dynamics of molecular liquids, where both intermolecular and intramolecular modes and the interaction among these modes play significant roles.…”

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

“…4,5 Recently, a single pulse 2D Raman technique developed by Silberberg and coworkers was implemented to overcome the most significant experimental obstacle in the form of parasitic low-order cascading process 6 and demonstrated the ability to measure intramolecular coupling of simple halogenated liquids. 7 Steady progress in the generation and manipulation of strong THz fields 8 stimulated the development of alternative spectroscopic path toward lowfrequency multidimensional spectroscopy -third-order 2D THz spectroscopy 9 which probes multipoint correlation function of the nuclear dipole moment of lowfrequency transitions. 2D THz spectroscopy was successfully realized on molecules in a gas phase 10,11 and semiconductor solids 12 , however, the still rather limited available energies and bandwidth of THz pulses, and the experimental limitation in generation and recombination of multiple THz pulses, have not allowed yet the real-ization of such experiments in liquids, where transition dipoles of the low-frequency modes are extremely small.…”