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Henrik G Kjaergaard - One of the best experts on this subject based on the ideXlab platform.
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molecular dynamic simulations of oh stretching Overtone induced photodissociation of fluorosulfonic and chlorosulfonic acid
Physical Chemistry Chemical Physics, 2010Co-Authors: Priyanka Gupta, Joseph R. Lane, Henrik G KjaergaardAbstract:We investigate the OH-stretching Overtone dynamics of fluorosulfonic acid (FSO3H) and chlorosulfonic acid (ClSO3H) using classical trajectory simulations. The initial nuclear coordinates and momenta for the trajectories are sampled from anharmonic correlation-corrected vibrational self consistent field (CC-VSCF) wavefunctions. We consider both OH-stretching Overtone states and combination states containing a mix of OH-stretching Overtones and SOH-bending or OSOH-torsional modes. Our molecular dynamics simulations confirm that photodissociation of these sulfonic acids to form the corresponding hydrogen halides and sulfur trioxide (HF + SO3 and HCl + SO3), is possible via highly vibrationally excited states on a picosecond timescale. Hydrogen-hopping events are also observed in the trajectories whereby the hydrogen atom of the excited OH group is found to migrate to one of the adjacent SO groups. The transition states, activation energies and dissociation dynamics of FSO3H and ClSO3H are found to be similar to those of H2SO4. We suggest that these halogenated sulfonic acids should be suitable proxy molecules for an experimental investigation of the OH-stretching Overtone induced photodissociation of H2SO4 thought to be important in Earths’ atmosphere.
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Fluorosulfonic acid and chlorosulfonic acid: possible candidates for OH-stretching Overtone-induced photodissociation.
The journal of physical chemistry. A, 2007Co-Authors: Joseph R. Lane, Henrik G KjaergaardAbstract:We have calculated the stationary points and internal reaction coordinate pathway for the dissociation of fluorosulfonic acid (FSO3H) and chlorosulfonic acid (ClSO3H). These sulfonic acids dissociate to sulfur trioxide and hydrogen fluoride and chloride, respectively. We have calculated the frequencies and intensities of the OH-stretching transitions of FSO3H and ClSO3H with an anharmonic oscillator local mode model. We find that excitation of the fourth and third OH-stretching Overtones provide adequate energy for photodissociation of FSO3H and ClSO3H, respectively. We propose that experimental detection of the products of OH-stretching Overtone-induced photodissociation of FSO3H and ClSO3H would be easier than the sulfuric acid (H2SO4) equivalent. The photodissociation of H2SO4 is thought to be important in the stratosphere. The FSO3H and ClSO3H experiment could be used in proxy to support the recently proposed OH-stretching Overtone-induced photodissociation mechanism of H2SO4.
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resonance coupling in the fourth oh stretching Overtone spectrum of formic acid
Journal of Chemical Physics, 2004Co-Authors: Daryl L Howard, Henrik G KjaergaardAbstract:The room-temperature vibrational Overtone spectra of the formic acid isotopomers HCOOH and DCOOH have been recorded in the third and fourth OH-stretching Overtone regions with intracavity laser photoacoustic spectroscopy. Resonance coupling between the OH- and CH-stretching vibrations in HCOOH is clearly identified in the fourth Overtone region. This is an example of strong coupling across bonds. In the third Overtone region, no resonance is observed. Vibrational energies and intensities of the OH- and CH-stretching Overtones and combination bands have been calculated with an anharmonic oscillator local mode model. The pure OH-stretching bright state carries almost all the intensity prior to resonance coupling.
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Vibrational Overtone Spectroscopy and Overtone Intensities of Cyclohexadiene Iron Tricarbonyl and 1,3-Cyclohexadiene
The Journal of Physical Chemistry A, 2001Co-Authors: A. V. Fedorov, D.l. Snavely, Henrik G Kjaergaard, Kathleen M. Gough, Brant E. BillinghurstAbstract:The CH stretching Overtone spectra of liquid cyclohexadiene iron tricarbonyl (CHDIT) have been recorded for the first, second, and third Overtone regions (∆V ) 2-4). The gaseous spectrum of CHDIT has also been obtained for the first Overtone region (∆V ) 2). Observed transitions are assigned to the Overtones of different nonequivalent CH bonds and to the local mode-normal mode combination bands. Oscillator strengths have been calculated with the harmonically coupled anharmonic oscillator (HCAO) local mode model and ab initio dipole moment functions. The theoretical values have been compared to the experimental oscillator strengths and agree well with experiment. The comparison of the Overtone spectrum of CHDIT to the corresponding spectrum of uncomplexed 1,3-cyclohexadiene reveal changes that occur in the ligand upon complexation with iron tricarbonyl. The presence of the metal lengthens the terminal olefinic CH bond by 0.002 A and shortens the nonterminal olefinic CH by 0.001 A. The axial and equatorial CH bonds of the free ligand become similar in length in the complex. The implications of the observed spectral features to the structure and bonding in the complex are discussed.
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Intensity of CH‐ and NH‐stretching transitions in the Overtone spectra of cyclopropylamine
The Journal of Chemical Physics, 1993Co-Authors: Bernadette I. Niefer, Henrik G Kjaergaard, Bryan R HenryAbstract:Vapor phase room temperature Overtone spectra of cyclopropylamine are measured both with conventional absorption spectroscopy for the lower Overtones and with intracavity laser photoacoustic spectroscopy for the higher Overtones. Spectra are recorded in both the CH‐stretching (ΔvCH=2–7) and NH‐stretching (ΔvNH=2–6) regions. The relative intensities of XH‐stretching peaks are explained in terms of the local mode model of harmonically coupled anharmonic oscillators, where all modes but the XH‐stretching modes are neglected. The dipole moment function is expanded in the XH‐stretching coordinates, with the expansion coefficients determined from ab initio molecular orbital calculations. The high number of peaks throughout the spectra makes assignment difficult, but allows the overlap of spectra from different experimental conditions. Thus it is possible to approximately determine the absolute intensities for the higher Overtone spectra that are obtained from the laser experiments. The simple intensity calculat...
E. Carry - One of the best experts on this subject based on the ideXlab platform.
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High-Overtone bulk-acoustic resonator gravimetric sensitivity: Towards wideband acoustic spectroscopy
Journal of Applied Physics, 2015Co-Authors: David Rabus, Eric Lebrasseur, Thierry Baron, Sylvain Ballandras, JEAN-MARIA FRIEDT, E. CarryAbstract:In the context of direct detection sensors with compact dimensions, we investigate the gravimetric sensitivity of High-Overtone Bulk Acoustic Resonators, through modeling of their acoustic characteristics and experiment. The high frequency characterizing such devices is expected to induce a significant effect when the acoustic field boundary conditions are modified by a thin adlayer. Furthermore, the multimode spectral characteristics is considered for wideband acoustic spectroscopy of the adlayer, once the gravimetric sensitivity dependence of the various Overtones is established. Finally, means of improving the gravimetric sensitivity by confining the acoustic field in a low acoustic-impedance layer is theoretically established.
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High-Overtone Bulk-Acoustic Resonator gravimetric sensitivity: towards wideband acoustic spectroscopy
Journal of Applied Physics, 2015Co-Authors: David Rabus, Eric Lebrasseur, Sylvain Ballandras, JEAN-MARIA FRIEDT, Thomas Baron, E. CarryAbstract:In the context of direct detection sensors with compact dimensions, we investigate the gravimetric sensitivity of high-Overtone bulk acoustic resonators, through modeling of their acoustic characteristics and experiment. The high frequency characterizing such devices is expected to induce a significant effect when the acoustic field boundary conditions are modified by a thin adlayer. Furthermore, the multimode spectral characteristics are considered for wideband acoustic spectroscopy of the adlayer, once the gravimetric sensitivity dependence of the various Overtones is established. Finally, means of improving the gravimetric sensitivity by confining the acoustic field in a low acoustic-impedance layer is theoretically established.
Veronica Vaida - One of the best experts on this subject based on the ideXlab platform.
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near infrared photochemistry of pyruvic acid in aqueous solution
Journal of Physical Chemistry A, 2012Co-Authors: Molly C Larsen, Veronica VaidaAbstract:Recent experimental and theoretical results have suggested that organic acids such as pyruvic acid, can be photolyzed in the ground electronic state by the excitation of the OH stretch vibrational Overtone. These Overtones absorb in the near-infrared and visible regions of the spectrum where the solar photons are plentiful and could provide a reaction pathway for the organic acids and alcohols that are abundant in the earth’s atmosphere. In this paper the Overtone initiated photochemistry of aqueous pyruvic acid is investigated by monitoring the evolution of carbon dioxide. In these experiments CO2 is being produced by excitation in the near-infrared, between 850 nm and ∼1150 nm (11 765–8696 cm–1), where the second OH vibrational Overtone (Δν = 3) of pyruvic acid is expected to absorb. These findings show not only that the Overtone initiated photochemical decarboxylation reaction occurs but also that in the aqueous phase it occurs at a lower energy than was predicted for the Overtone initiated reaction of...
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dynamics of vibrational Overtone excited pyruvic acid in the gas phase line broadening through hydrogen atom chattering
Journal of Physical Chemistry A, 2008Co-Authors: Kaito Takahashi, Kathryn L Plath, Rex T Skodje, Veronica VaidaAbstract:The dynamics of Overtone-excited pyruvic acid (PA) is studied using a combination of experimental and theoretical methods. It is experimentally observed that high Overtone excitation of the OH-stretching mode of PA in the gas phase leads to a unimolecular decarboxylation reaction. An RRKM analysis of the rate is consistent with previous experiments for the thermal reaction but is inconsistent with the present Overtone chemistry; from this it is concluded that the Overtone-induced reaction is likely to be a direct reaction. Using a Fourier transform infrared spectrometer and a cavity ring-down spectrometer, the spectrum for the OH-stretch fundamental and Overtone transitions is measured. We assign two conformers of PA in the spectrum, the Tc and Tt, corresponding to distinct orientations of the OH-group. The spectral peaks for the Tc-conformer broaden dramatically at the third and fourth Overtones while those of the Tt-conformer remain relatively narrow. Using a three-mode quantum mechanical model for the ...
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Experimental absolute intensities of the 4ν9 and 5ν9 O–H stretching Overtones of H2SO4
Chemical Physics Letters, 2006Co-Authors: Karl J. Feierabend, Steven S. Brown, Daniel K. Havey, Veronica VaidaAbstract:This work uses cavity ring-down spectroscopy to measure two high vibrational Overtones (4ν9 and 5ν9) of the O–H stretch in sulfuric acid. The frequencies, bandwidths, and intensities are obtained for these previously unobserved transitions. The atmospheric J-values for the Overtone-induced photodissociation are calculated using the experimental cross-sections. Accurate J-values are essential for understanding the formation of the springtime polar sulfate layer by Overtone-induced dehydration of H2SO4. The results are compared to previous experimental and theoretical studies of sulfuric acid.
David Rabus - One of the best experts on this subject based on the ideXlab platform.
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High-Overtone bulk-acoustic resonator gravimetric sensitivity: Towards wideband acoustic spectroscopy
Journal of Applied Physics, 2015Co-Authors: David Rabus, Eric Lebrasseur, Thierry Baron, Sylvain Ballandras, JEAN-MARIA FRIEDT, E. CarryAbstract:In the context of direct detection sensors with compact dimensions, we investigate the gravimetric sensitivity of High-Overtone Bulk Acoustic Resonators, through modeling of their acoustic characteristics and experiment. The high frequency characterizing such devices is expected to induce a significant effect when the acoustic field boundary conditions are modified by a thin adlayer. Furthermore, the multimode spectral characteristics is considered for wideband acoustic spectroscopy of the adlayer, once the gravimetric sensitivity dependence of the various Overtones is established. Finally, means of improving the gravimetric sensitivity by confining the acoustic field in a low acoustic-impedance layer is theoretically established.
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High-Overtone Bulk-Acoustic Resonator gravimetric sensitivity: towards wideband acoustic spectroscopy
Journal of Applied Physics, 2015Co-Authors: David Rabus, Eric Lebrasseur, Sylvain Ballandras, JEAN-MARIA FRIEDT, Thomas Baron, E. CarryAbstract:In the context of direct detection sensors with compact dimensions, we investigate the gravimetric sensitivity of high-Overtone bulk acoustic resonators, through modeling of their acoustic characteristics and experiment. The high frequency characterizing such devices is expected to induce a significant effect when the acoustic field boundary conditions are modified by a thin adlayer. Furthermore, the multimode spectral characteristics are considered for wideband acoustic spectroscopy of the adlayer, once the gravimetric sensitivity dependence of the various Overtones is established. Finally, means of improving the gravimetric sensitivity by confining the acoustic field in a low acoustic-impedance layer is theoretically established.
Eric Lebrasseur - One of the best experts on this subject based on the ideXlab platform.
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High-Overtone bulk-acoustic resonator gravimetric sensitivity: Towards wideband acoustic spectroscopy
Journal of Applied Physics, 2015Co-Authors: David Rabus, Eric Lebrasseur, Thierry Baron, Sylvain Ballandras, JEAN-MARIA FRIEDT, E. CarryAbstract:In the context of direct detection sensors with compact dimensions, we investigate the gravimetric sensitivity of High-Overtone Bulk Acoustic Resonators, through modeling of their acoustic characteristics and experiment. The high frequency characterizing such devices is expected to induce a significant effect when the acoustic field boundary conditions are modified by a thin adlayer. Furthermore, the multimode spectral characteristics is considered for wideband acoustic spectroscopy of the adlayer, once the gravimetric sensitivity dependence of the various Overtones is established. Finally, means of improving the gravimetric sensitivity by confining the acoustic field in a low acoustic-impedance layer is theoretically established.
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High-Overtone Bulk-Acoustic Resonator gravimetric sensitivity: towards wideband acoustic spectroscopy
Journal of Applied Physics, 2015Co-Authors: David Rabus, Eric Lebrasseur, Sylvain Ballandras, JEAN-MARIA FRIEDT, Thomas Baron, E. CarryAbstract:In the context of direct detection sensors with compact dimensions, we investigate the gravimetric sensitivity of high-Overtone bulk acoustic resonators, through modeling of their acoustic characteristics and experiment. The high frequency characterizing such devices is expected to induce a significant effect when the acoustic field boundary conditions are modified by a thin adlayer. Furthermore, the multimode spectral characteristics are considered for wideband acoustic spectroscopy of the adlayer, once the gravimetric sensitivity dependence of the various Overtones is established. Finally, means of improving the gravimetric sensitivity by confining the acoustic field in a low acoustic-impedance layer is theoretically established.
