scholarly journals Viscosity Dependence of the Ultrafast Vibrational Dynamics of Borohydride in NaOH Solutions: Crowding Effect on Dihydrogen Bonds

2019 ◽  
Author(s):  
Clinton Johnson ◽  
Kai C. Gronborg ◽  
Thomas Brinzer ◽  
Zhe Ren ◽  
Sean Garrett-Roe
Keyword(s):  
Ground State ◽  
Vibrational Energy ◽  
Vibrational Energy Relaxation ◽  
Energy Redistribution ◽  
Vibrational Dynamics ◽  
Structure And Dynamics ◽  
2D Ir ◽  
Intramolecular Vibrational Energy Redistribution ◽  
Two Dimensional Infrared Spectroscopy ◽  
Viscosity Dependence

<p>Two-dimensional infrared spectroscopy (2D-IR) probes the local solvent structure and dynamics of the nu<sub>3</sub> mode (BH antisymmetric stretch) of borohydride (BH<sub>4</sub><sup>-</sup> ) in aqueous solution. The 2D-IR spectra of the BH stretches have broad and overlapping bands. Vibrational energy relaxation occurs on a 2 ps timescale. Energy that is initially deposited in BH stretching modes and directly in the solvent generates a long lived hot ground state. Before the hot ground state appears, some indications of intramolecular vibrational energy redistribution are observed. The solvent viscosity was varied (1.5–6 cP) by increasing the hydroxide concentration (0.1–7 M). Within the vibrational lifetime of the BH stretching modes, the rate of structural relaxation slows proportionally to the viscosity due to the overlap of the ions’s solvation shells.</p>

scholarly journals Viscosity Dependence of the Ultrafast Vibrational Dynamics of Borohydride in NaOH Solutions: Crowding Effect on Dihydrogen Bonds

2019 ◽  
Author(s):  
Clinton Johnson ◽  
Kai C. Gronborg ◽  
Thomas Brinzer ◽  
Zhe Ren ◽  
Sean Garrett-Roe
Keyword(s):  
Ground State ◽  
Vibrational Energy ◽  
Vibrational Energy Relaxation ◽  
Energy Redistribution ◽  
Vibrational Dynamics ◽  
Structure And Dynamics ◽  
2D Ir ◽  
Intramolecular Vibrational Energy Redistribution ◽  
Two Dimensional Infrared Spectroscopy ◽  
Viscosity Dependence

<p>Two-dimensional infrared spectroscopy (2D-IR) probes the local solvent structure and dynamics of the nu<sub>3</sub> mode (BH antisymmetric stretch) of borohydride (BH<sub>4</sub><sup>-</sup> ) in aqueous solution. The 2D-IR spectra of the BH stretches have broad and overlapping bands. Vibrational energy relaxation occurs on a 2 ps timescale. Energy that is initially deposited in BH stretching modes and directly in the solvent generates a long lived hot ground state. Before the hot ground state appears, some indications of intramolecular vibrational energy redistribution are observed. The solvent viscosity was varied (1.5–6 cP) by increasing the hydroxide concentration (0.1–7 M). Within the vibrational lifetime of the BH stretching modes, the rate of structural relaxation slows proportionally to the viscosity due to the overlap of the ions’s solvation shells.</p>

Two-Dimensional Infrared Spectroscopy From the Gas to Liquid Phase: Density Dependent J-Scrambling, Vibrational Relaxation, and the Onset of Liquid Character

2019 ◽  
Author(s):  
Greg Ng Pack ◽  
Matthew Rotondaro ◽  
Parth Shah ◽  
Aritra Mandal ◽  
Shyamsunder Erramilli ◽  
...  
Keyword(s):  
Vibrational Energy ◽  
Rotational Relaxation ◽  
Vibrational Energy Relaxation ◽  
Pump Probe ◽  
Solution Dynamics ◽  
Supercritical Phase ◽  
Supercritical Solution ◽  
Asymmetric Stretch ◽  
Two Dimensional Infrared Spectroscopy ◽  
Vibrational Equilibrium

Ultrafast 2DIR spectra and pump-probe responses of the N2O n 3 asymmetric stretch in SF6 as a function of density from the gas to supercritical phase and liquid are reported. 2DIR spectra unequivocally reveal free rotor character at all densities studied in the gas and supercritical region. Analysis of the 2DIR spectra determines that J-scrambling or rotational relaxation in N2O is highly efficient, occurring in ~1.5 to ~2 collisions with SF6 at all non-liquid densities. In contrast, N2O n 3 vibrational energy relaxation requires ~15 collisions, and complete vibrational equilibrium occurs on the ~ns scale at all densities. An independent binary collision model is sufficient to describe these supercritical state point dynamics. The N2O n 3 in liquid SF6 2DIR spectrum shows no evidence of free rotor character or spectral diffusion. Using these 2DIR results, hindered rotor or liquid-like character is found in gas and all supercritical solutions for SF6 densities ³ r * = 0.3, and increases with SF6 density. 2DIR spectral analysis offers direct time domain evidence of critical slowing for SF6 solutions closest to the critical point density. Applications of 2DIR to other high density and supercritical solution dynamics and descriptions are discussed. <br>

Multiple timescales in the intramolecular vibrational energy redistribution of highly excited methanol

1995 ◽  
Vol 102 ◽  
pp. 167 ◽  
Author(s):  
Lucia Lubich ◽  
Oleg V. Boyarkin ◽  
Rebecca D. F. Settle ◽  
David S. Perry ◽  
Thomas R. Rizzo
Keyword(s):  
Vibrational Energy ◽  
Energy Redistribution ◽  
Multiple Timescales ◽  
Intramolecular Vibrational Energy Redistribution

scholarly journals Intramolecular vibrational energy redistribution and the quantum ergodicity transition: a phase space perspective

2020 ◽  
Vol 22 (20) ◽  
pp. 11139-11173 ◽  
Author(s):  
Sourav Karmakar ◽  
Srihari Keshavamurthy
Keyword(s):  
Phase Space ◽  
Energy Flow ◽  
Vibrational Energy ◽  
Energy Redistribution ◽  
Quantum Ergodicity ◽  
Connected Network ◽  
Intramolecular Vibrational Energy Redistribution ◽  
Vibrational Energy Flow ◽  
Classical Phase Space

The onset of facile intramolecular vibrational energy flow can be related to features in the connected network of anharmonic resonances in the classical phase space.

scholarly journals Direct observation of structural dynamics upon photo-excitation in a spin crossover crystal with femtosecond electron diffraction

2019 ◽  
Vol 205 ◽  
pp. 07005
Author(s):  
Yifeng Jiang ◽  
Lai Chung Liu ◽  
Henrike M. Müller-Werkmeister ◽  
Cheng Lu ◽  
Dongfang Zhang ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Structural Dynamics ◽  
Spin Crossover ◽  
Vibrational Energy ◽  
Intersystem Crossing ◽  
Structural Reorganization ◽  
Energy Redistribution ◽  
Intramolecular Vibrational Energy Redistribution ◽  
Femtosecond Electron Diffraction ◽  
Ligand Bond

Photoinduced spin transitions are studied by femtosecond electron diffraction to understand ultrafast structural dynamics associated with intersystem crossing. The results indicate the structural reorganization occurs within 2.3 ps, as the metal-ligand bond distribution narrows during intramolecular vibrational energy redistribution.

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