Time and frequency-Gated FID: a new approach to study the vibrational dephasing of water

Abstract

Abstract. The ultrafast frequency-resolved upconverted vibrational free induction decay (FID) of HDO in D 2 O was measured, allowing extraction of the amplitude and phase of the coherent transient. The FID Wigner spectrogram shows evidence of λ-dependent dynamics.Considerable experimental and theoretical effort has been expended toward understanding the behavior of liquid water at the molecular level, much of it striving to understand the structural and dynamical character of its hydrogen bonding interactions. Investigations of the hydrogen bonding nature of water via vibrational spectroscopy have focused on the OH-stretching band in the 3 µm region. The broad frequency profile of this band and the correlation between stretching frequency and hydrogen bond strength has prompted debate over the possible existence of distinct hydrogen-bonded species and their timescales of Femtosecond mid-infrared (MIR) pulses were generated by a type-I optical parametric amplifier (OPA) based on the nonlinear crystal KNbO 3 (KN).[7] The OPA is pumped by the fundamental of a home-built Ti:sapphire regenerative amplifier and seeded with the near-infrared portion of a white light continuum

Ultrafast Dephasing of Single Nanoparticles Studied by Two-Pulse Second-Order Interferometry

“…The ultrafast interferometric responses of single chromophores, if spectrally resolved, could provide more detailed information of homogeneous dynamics of different molecular states. 66 Both extensions are being explored.…”

The Future of Pulse Measurement: New Dilemmas

“…The lack of specificity in the transient absorbance spectrum, however, can become a problem when the features are broad and overlapping, as is often the case for biological molecules. As a result, a few researchers are looking directly at ultrafast emission or fluorescence [77][78][79]. The emitted luminescence (in particular, its intensity and phase vs. time) of a chromophore is sensitive to its electronic state, its conformation, and its surrounding environment.…”