Two-Dimensional Infrared (2D IR) Spectroscopy

Buchanan, Lauren E.; Xiong, Wei

doi:10.1016/b978-0-12-803581-8.09527-8

Cited by 9 publications

(9 citation statements)

References 150 publications

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“…3A) spectroscopy. 2D IR measures the third-order nonlinear optical response function of a material, providing detailed spectral and dynamical features (14,(26)(27)(28)(29)(30)(31) hidden from pump-probe spectra. Specifically, 2D IR can state-selectively excite and probe particular transitions, a feature that is critical to discern the origin of nonlinearities in polaritons and dark modes.…”

Section: Origin Of Polariton Bleach and Rabi Oscillation Dynamics Rev...mentioning

confidence: 99%

Manipulating optical nonlinearities of molecular polaritons by delocalization

et al. 2019

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Optical nonlinearities are key resources in the contemporary photonics toolbox, relevant to quantum gate operations and all-optical switches. Chemical modification is often employed to control the nonlinear response of materials at the microscopic level, but on-the-fly manipulation of such response is challenging. Tunability of optical nonlinearities in the mid-IR is even less developed, hindering its applications in chemical sensing or IR photonic circuitry. Here, we report control of vibrational polariton coherent nonlinearities by manipulation of macroscopic parameters such as cavity longitudinal length or molecular concentration. Further 2D IR investigations reveal that nonlinear dephasing provides the dominant source of the observed ultrafast polariton nonlinearities. The reported phenomena originate from the nonlinear macroscopic polarization stemming from strong coupling between microscopic molecular excitations and a macroscopic photonic cavity mode. RESULTS. Polariton bleach dependence on cavity longitudinal length.To investigate the optical nonlinearities of vibrational polaritons, we measure their third-order nonlinear susceptibilities by femtosecond IR pumpprobe spectroscopy. The hybrid light-matter system consists of a FP microcavity filled with an ensemble of asymmetric carbonyl stretch modes originating from W(CO)6 molecules in a hexane solution (14). At zero waiting time, when IR pump and probe pulses overlap, we see a notable reduction in the intensity of the polariton transmission (Figs. 1b). This reduction gives rise to absorptive features in the differential transmission spectra (Figs. 1c). Qualitatively, the observed behavior resembles the well-known "photon blockade effect" in the single-emitter quantum regime of the Jaynes-Cummings model (18)(19)(20): when a photon excites the emitter-cavity system, the latter is blocked from further interactions with incoming photons of the same frequency. Here, we observe a similar effect, although it is in the ensemble regime and the mechanism for reduced transmission is quite different from the single oscillator case. We hereafter term this phenomenon "polariton bleach". Note this effect is not a trivial coherent artifact from the overlap between the pump and probe pulses. The IR pulse duration is ~100 fs, while the bleach lasts for less than 5 ps (which is also the approximate lifetime of the cavity photon), indicating the effect is intrinsic to the lifetime of the cavity polaritons. The polariton bleach concept provides a foundation for developing mid-IR photonic devices in the ensemble regime of light-matter strong coupling. Chen for his help on designing Figure 1 and Jiaxi Wang for her help on the experiments.

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Section: Origin Of Polariton Bleach and Rabi Oscillation Dynamics Rev...mentioning

confidence: 99%

Manipulating optical nonlinearities of molecular polaritons by delocalization

et al. 2019

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“…Both polariton and dark modes have been studied, and their spectroscopic signatures have been reported by us and others. 1,2,6 In this work, building on our previous study, we describe the first state-resolved dynamics of molecular vibrational polaritons, using time-resolved pump−probe and two-dimensional infrared (2D IR) spectroscopy 31,32 (experimental setup illustrated in Figure 1c). Both spectroscopies are critical to characterize molecular vibrational polariton ultrafast physics, because unlike exciton-polaritons, vibrational-polaritons feature many more intramolecular vibrational relaxation pathways that can suppress their fluorescence, making techniques 10,26,27,33−39 developed for characterization of exciton-polaritons inapplicable here.…”

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confidence: 99%

“…Pump Probe and 2D IR Spectroscopy. The spectrometer follows the pulse shaper enabled 2D IR 31,32,42 setup, and a rotational stage is added to control beam incidence angle. In the 2D IR spectrometer, two pump-IR pulses and one probe-IR pulse interact with a sample sequentially to create two vibrational coherences.…”

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State-Selective Polariton to Dark State Relaxation Dynamics

et al. 2019

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The modification of vibrational dynamics is essential for controlling chemical reactions and IR photonic applications. The hybridization between cavity modes and molecular vibrational modes provides a new way to control molecular dynamics. In this work, we study the dynamics of molecular vibrational polaritons in various solvent environments. We find the dynamics of the polariton system is strongly influenced by the nature of the solvents. While the relaxation from upper polariton (UP) to dark modes is always fast (<5 ps) regardless of the medium, lower polariton (LP) in low polarity solvents shows much slower transfer (10–30 ps) into dark modes, despite the fact that the LP lifetime remains within 5 ps. This result suggests that in the latter media, the energy pumped into the LP is first transferred into intermediate states which only subsequently decay into dark modes. In contrast, in solvent environments that strongly interact with the solute, the LP population relaxes into the dense dark state manifold within a much faster time scale. We propose the intermediate state to be the high-lying excited states of dark modes, which are effectively populated by LP via, e.g., ladder-climbing. Such population in the high-lying states can be retained for tens of picoseconds, which could be pertinent to recently observed cavity-modified chemistry.

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“…The further image processing was finished using Nanoscope Analysis software (version 1.5, Bruker Corporation). All generalized two-dimensional correlation spectral (2DCOS) analyses were performed in 2D-shige software 28 , 40 , 41 . Images of two-dimensional correlation spectra were implemented using a homemade Matlab program.…”

Section: Methodsmentioning

confidence: 99%

New insights into the autofluorescence properties of cellulose/nanocellulose

Ding

Han

et al. 2020

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This work explored the fluorescence properties of nano/cellulose isolated from bleached softwood kraft pulp by TEMPO oxidation. Fluorescence spectra showed that all samples exhibited a typical emission peak at 574 nm due to the probabilistic formation of unsaturated bonds by glycosidic bonds independent of lignin. Increasing the excitation wavelengths (510–530 nm) caused red shift of fluorescence emission peaks (570–585 nm) with unchanged fluorescence intensity. Conversely, changing acid/alkaline conditions led to an increase of fluorescence intensity with no shifting of fluorescence emission peak. This can be attributed to an increase in the polarity of the solution environment but does not cause interaction of functional groups within the system identified by generalized two-dimensional correlation fluorescence spectroscopy. This study provides new insight in applying nano/cellulose with special luminous characteristics in biomedicine area such as multi-color biological imaging and chemical sensing.

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Two-Dimensional Infrared (2D IR) Spectroscopy

Cited by 9 publications

References 150 publications

Manipulating optical nonlinearities of molecular polaritons by delocalization

Manipulating optical nonlinearities of molecular polaritons by delocalization

State-Selective Polariton to Dark State Relaxation Dynamics

New insights into the autofluorescence properties of cellulose/nanocellulose

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