Femtosecond Time-Resolved Infrared-Resonant Third-Order Sum-Frequency Spectroscopy

Abstract

We demonstrate a coherent vibrational spectroscopy based on molecular infrared (IR)-active resonance. We apply two femtosecond pulses (one in near-IR and the other in mid-IR) to generate the femtosecond time-resolved IR-resonant third-order sumfrequency signal. The mid-IR pulse is tuned to be resonant with molecular vibrations. This experimental configuration converts the IR light into a visible signal and exhibits high sensitivity to the vibrational mode of the molecule. The technique can be applied to acquire chemical information on various biological samples, including living tissues in their natural water-rich state. This approach can also be used to study the dynamics of IRactive vibrational modes, that is, measure the decoherence time.

Parametric Nonlinear Optics with Layered Materials and Related Heterostructures

“…It can provide a deeper insight into interactions of different vibrational and electronic states by resonant excitation of multiple states. [ 150–152 ] A time‐resolved extension of TSF spectroscopy with $$\omega _1 = \omega _2 = \omega _3$$ (i.e., pump–THG‐probe) was recently exploited by Morrow et al., to measure multidimensional transient spectra on polycrystalline thin films and spiral nanostructures of MoS 2 and WS 2 . [ 153 ] Besides the possibility to isolate transitions with large dipole moments ( Figure a) due to the $$\mu ^8$$ scaling of the TSF signal with transition dipole $$\mu$$, TSF probe provided high contrast signal for the investigated nanostructure morphologies (Figure 6b).…”

Infrared spectroscopic monitoring of solid-state processes

“…50–52 IR spectroscopic insight to even faster phenomena, which occur at the femtosecond time scale, are enabled by the recent development of advanced laser pump–probe methodologies. 53–57 The range of mid-IR electromagnetic waves covers the ∼10–300 fs region, which defines the limit of time resolution that can be achieved by IR spectroscopy.…”

“…393 This is especially true for surface and interface phenomena, where there is plenty of room for further development. 57,394–398 The development in the field of femtosecond IR spectroscopy also promises deep insight into ultrafast dynamics of solid-state systems, and significant breakthroughs are also to be expected here. 399–401…”