Local Modes of Vibration: The Effect of Low‐Frequency Vibrations

Vogt, Emil; Hansen, Anne S.; Kjaergaard, Henrik G.

doi:10.1002/9783527814596.ch14

Cited by 2 publications

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“…The coupling between the two OH-stretching oscillators in ( t -BuOOH) 2 was estimated using a two-dimensional (2D) harmonically coupled anharmonic oscillator LM (HCAO LM) model. , The 2D PES was sampled along the displacement coordinates of the two chemically equivalent oscillators: q 1 , q 2 = [−0.075; 0.075 Å] in 0.025 Å increments around the ωB97X-D/AVTZ equilibrium geometry. The force constants were determined by fitting the 7 × 7 PES grid to a 2D polynomial to the sixth order.…”

Section: Computational Detailsmentioning

confidence: 99%

“…The force constants were determined by fitting the 7 × 7 PES grid to a 2D polynomial to the sixth order. The harmonic coupling was then estimated from the second-order force constants by , γ ′ = prefix− 1 2 F 12 F 11 F 22 · ω̃ where γ′ is the coupling parameter, F ij is the second-order derivative of the PES with respect to the displacement coordinates, ω̃ = F 11 μ OH / ( 2 π c ) is the harmonic transition wavenumber of the OH b -stretch, and μ OH is the reduced mass of the oscillator.…”

Section: Computational Detailsmentioning

confidence: 99%

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Gas-Phase Room-Temperature Detection of the tert-Butyl Hydroperoxide Dimer

Jensen,

Kjaergaard

2023

J. Phys. Chem. A

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We have detected the tert-butyl hydroperoxide dimer, (t-BuOOH) 2 , in the gas phase at room temperature using conventional FTIR techniques. The dimer is identified by an asymmetric absorbance band assigned to the fundamental hydrogen-bound OH b -stretch. The weighted band maximum of the dimer OH b -stretch is located at ∼3452 cm −1 , red-shifted by ∼145 cm −1 from the monomer OH-stretching band. The gas-phase dimer assignment is supported by Ar matrix isolation FTIR experiments at 12 K and experiments with a partially deuterated sample. Computationally, we find the lowest energy structure of (t-BuOOH) 2 to be a doubly hydrogen bound six-membered ring with non-optimal hydrogen bond angles. We estimate the gas-phase constant of dimer formation, K, to be 0.4 (standard pressure of 1 bar) using the experimental integrated absorbance and a theoretically determined oscillator strength of the OH b -stretching band.

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Section: Computational Detailsmentioning

confidence: 99%