Effect of ion–molecule interaction on fermi-resonance in acetonitrile studied by ultrafast vibrational spectroscopy

Kwon, Young Ah; Lee, Chiho; Park, Sungnam

doi:10.1016/j.chemphys.2014.10.017

Cited by 23 publications

(30 citation statements)

References 48 publications

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“…This decrease in the coupling upon interaction with metal ions is consistent with the previously reported decrease of W for Li + -coordinated conventional CH 3 CN compared to the free CD 3 13 CN ( W = 14.3 vs 19.6 cm –1 , respectively). 64 Furthermore, in our case, the most polarizing and hence the most perturbing Zn 2+ and Mg 2+ cations disrupt the FR completely for the cation-coordinated solvent. This is obvious in Zn 2+ electrolytes that demonstrate only a single peak of the cation-coordinated C≡N stretch around 2256 cm –1 in the presence of high quantities of Zn 2+ salt ( Figure 7 d).…”

Section: Resultsmentioning

confidence: 57%

“…The main issue with the protiated family is the presence of the combination band of C–C stretch and C–H bend at frequencies higher than the C≡N stretch band that gains intensity from the latter via Fermi resonance ( Figure 1 a and Table S2 ). 64 Accidental FR is a common situation in this spectral region 84 and significantly complicates IR spectroscopy of the local modes. The key point is that the combination band not only borrows oscillator strength of the marker mode, thus effectively decreasing its intensity, but its location at higher frequencies and 30 cm –1 spectral separation from the C≡N band overlaps it significantly with the IR band of the cation-coordinated acetonitrile for most of the cations of interest ( Figures 2 c and S4 ).…”

Section: Resultsmentioning

confidence: 99%

“…This magnitude of Fermi coupling constant is slightly lower than that in neat conventional CH 3 CN ( W = 19.6 cm –1 ). 64 …”

Section: Resultsmentioning

confidence: 99%

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Characterization of Acetonitrile Isotopologues as Vibrational Probes of Electrolytes

et al. 2021

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Acetonitrile has emerged as a solvent candidate for novel electrolyte formulations in metal-ion batteries and supercapacitors. It features a bright local C≡N stretch vibrational mode whose infrared (IR) signature is sensitive to battery-relevant cations (Li + , Mg 2+ , Zn 2+ , Ca 2+ ) both in pure form and in the presence of water admixture across a full possible range of concentrations from the dilute to the superconcentrated regime. Stationary and time-resolved IR spectroscopy thus emerges as a natural tool to study site-specific intermolecular interactions from the solvent perspective without introducing an extrinsic probe that perturbs solution morphology and may not represent the intrinsic dynamics in these electrolytes. The metal-coordinated acetonitrile, water-separated metal–acetonitrile pair, and free solvent each have a distinct vibrational signature that allows their unambiguous differentiation. The IR band frequency of the metal-coordinated acetonitrile depends on the ion charge density. To study the ion transport dynamics, it is necessary to differentiate energy-transfer processes from structural interconversions in these electrolytes. Isotope labeling the solvent is a necessary prerequisite to separate these processes. We discuss the design principles and choice of the CD 3 13 CN label and characterize its vibrational spectroscopy in these electrolytes. The Fermi resonance between 13 C≡N and C–D stretches complicates the spectral response but does not prevent its effective utilization. Time-resolved two-dimensional (2D) IR spectroscopy can be performed on a mixture of acetonitrile isotopologues and much can be learned about the structural dynamics of various species in these formulations.

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Section: Resultsmentioning

confidence: 57%

Section: Resultsmentioning

confidence: 99%

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Characterization of Acetonitrile Isotopologues as Vibrational Probes of Electrolytes

et al. 2021

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“…Twelve such representative pathways showing the temporal evolution from left to right of the density matrix elements contributing to the signal polarization [31][32][33] are shown in Fig. 3, and all 36 of these pathways are summarized in SI (Fig.…”

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confidence: 99%

Ultrafast Two-Dimensional Infrared Spectroscopy of a Quasifree Rotor: J Scrambling and Perfectly Anticorrelated Cross Peaks

et al. 2018

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Ultrafast two-dimensional infrared (2DIR) spectra of the N_{2}O ν_{3} mode in moderately dense SF_{6} gas exhibit complex line shapes with diagonal and antidiagonal features in contrast to condensed phase vibrational 2DIR spectroscopy. Observed spectra for this quasifree rotor system are well captured by a model that includes all 36 possible rovibrational pathways and treats P (ΔJ=-1) and R (ΔJ=+1) branch resonances as distinct Kubo line shape features. Transition frequency correlation decay is due to J scrambling within one to two gas collisions at each density. Studies of supercritical solvation and relaxation at high pressure and temperature are enabled by this methodology.

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“…Consequently, Fermi resonances are used to aid assignment of peaks probed in Raman scattering and infrared absorption spectra that do not correspond with known fundamental vibrations. The investigation of Fermi resonance has great significance not only in the areas of physics and chemistry, such as the establishment of Fermi resonance modeling, solvent effects, isotopic effects, ion–molecule interaction, vibrational lifetime and hydrogen bond, but also for practical applications in the field of material science, biology (protein transfer), geology and sensor . Although past research has yielded fruitful results, it is still a significant challenge to fully explore the mechanisms of Fermi resonance.…”

Section: Introductionmentioning

confidence: 99%

Pressure‐induced Fermi resonance between fundamental modes in 7,7,8,8‐tetracyanoquinodimethane

Sun

Hong-liang

Liu

et al. 2017

J Raman Spectroscopy

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Herein, in‐situ high pressure Raman spectra of 7,7,8,8‐tetracyanoquinodimethane (TCNQ) have been measured up to 10 GPa, and a first‐order phase transition was detected at about 2.3 GPa. An anharmonic coupling (Fermi resonance) between fundamental modes was observed. The relationship of Fermi resonance parameters (intensity ratio, coupling coefficient, frequency separation and frequency separation of unperturbed transition) with pressure was discussed. The frequency separation dominated the decay of the intensity ratio of Fermi resonance doublets, and this would be another character of anharmonic coupling between fundamental modes. Copyright © 2017 John Wiley & Sons, Ltd.

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Effect of ion–molecule interaction on fermi-resonance in acetonitrile studied by ultrafast vibrational spectroscopy

Cited by 23 publications

References 48 publications

Characterization of Acetonitrile Isotopologues as Vibrational Probes of Electrolytes

Characterization of Acetonitrile Isotopologues as Vibrational Probes of Electrolytes

Ultrafast Two-Dimensional Infrared Spectroscopy of a Quasifree Rotor: J Scrambling and Perfectly Anticorrelated Cross Peaks

Pressure‐induced Fermi resonance between fundamental modes in 7,7,8,8‐tetracyanoquinodimethane

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