Transfer and storage of vibrational energy in liquids: collisional up-pumping of carbon monoxide in liquid argon

Anex, Deon S.; Ewing, George E.

doi:10.1021/j100399a030

Cited by 22 publications

(5 citation statements)

References 6 publications

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“…A measurement of a <100 fs anisotropy decay in the ν OH band of neat water was attributed to very fast intra- and intermolecular vibrational energy hopping. Intermolecular vibrational energy transfer is ordinarily thought to be inefficient in polyatomic liquids and solutions, where VER is usually faster than hopping between adjacent molecules, although intermolecular transfer can be quite efficient in the long-lived vibrations of diatomic liquids or solutions. , A few studies have shown moderately efficient intermolecular transfer in polyatomic solutions provided there are strong interactions such as hydrogen bonds between donors and acceptors. , Thus, it is a very interesting and possibly unique feature of water that intermolecular vibrational transfer is so efficient that it can effectively compete with a ∼1 ps VER decay rate …”

Section: Introductionmentioning

confidence: 99%

Vibrational Energy Relaxation and Spectral Diffusion in Water and Deuterated Water

et al. 2000

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In the broad water stretching band (2900−3700 cm-1), frequency-dependent vibrational energy relaxation (VER), and spectral diffusion both occur on the time scale of a few picoseconds. Ultrafast IR−Raman spectroscopy of water is used to study both processes. VER is also studied in solutions of HDO in D2O (HDO/D2O). The OH stretch (νOH) lifetime for water and HDO is ∼1 ps. The OD stretch (νOD) lifetime for D2O is ∼2 ps. Stretch decay generates substantial excitation of the bending modes. The lifetimes of bending vibrations (δ) in H2O, HDO, and D2O can be estimated to be in the 0.6 ps ≤ T 1 ≤ 1.2 ps range. νOH decay in water produces δH 2 O with a quantum yield 1.0 ≤ φ ≤ 2.0. In HDO/D2O solutions, νOH(HDO) decay generates νOD(D2O), δHDO, and δD 2 O. The quantum yield for generating νOD(D2O) is φ ≈ 0.1. The quantum yield for generating both δHDO and δD 2 O is φ ≥ 0.6. Thus, each νOH(HDO) decay generates at minimum 1.2 quanta of bending excitation. After narrow-band pumping, the distribution of excitations within the stretch band of water evolves in time. Pumping on the blue edge instantaneously (within ∼1 ps) generates excitations throughout the band. Pumping on the red edge does not instantaneously generate excitations at the blue edge. Excitations migrate uphill to the blue edge on the 0−2 ps time scale. The fast downhill spectral diffusion is attributed to excitation hopping among water molecules in different structural environments. The slower uphill spectral diffusion is attributed to evolution of the local liquid structure. Shortly after excitations are generated, an overall redshift is observed that is attributed to a dynamic vibrational Stokes shift. This dynamic shift slows down the rate of excitation hopping. Then energy redistribution throughout the band becomes slow enough that the longer VER lifetimes of stretch excitations on the blue edge can lead to a gradual blue shift of population over the next few picoseconds.

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Section: Introductionmentioning

confidence: 99%

Vibrational Energy Relaxation and Spectral Diffusion in Water and Deuterated Water

et al. 2000

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“…This approach allows the sustaining of strong vibrational disequilibrium at high densities and a low power budget. Optical pumping by a CO laser has been previously achieved in gas phase carbon monoxide [2][3][4][5][6][7] at pressures of up to 20 atm [2], gas phase nitric oxide [8,9], liquid phase CO [10,11], and solid CO and NO matrices [12,13]. Recently, optical pumping has also been demonstrated in infrared inactive gases, such as nitrogen and air, at atmospheric pressure [14].…”

Section: Introductionmentioning

confidence: 99%

“…In the experiments of [2][3][4][5][6][7][8][9][10][11][12][13][14], the CO laser power was fairly low, ranging from a few watts to 200 W continuous wave (c.w.). Ionization in optically pumped gases is produced by an associative ionization mechanism, in collisions of two highly vibrationally excited molecules when the sum of their vibrational energies exceeds the ionization potential [6,15,16]:…”

Section: Introductionmentioning

confidence: 99%

Ionization measurements in optically pumped discharges

Plönjes

Palm

Adamovich

et al. 2000

J. Phys. D: Appl. Phys.

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The kinetics of ionization and electron removal in optically pumped non-equilibrium plasmas sustained by a CO laser are studied using non-self-sustained dc and RF electric discharges. Experiments in optically pumped CO/Ar/N2 mixtures doped with O2 and NO demonstrated that associative ionization of CO produces free electrons at a rate up to S = 1015 cm-3 s-1. The ionization rate coefficient, inferred from the CO vibrational population measurements, is kion = (1.1-1.8)×10-13 cm3 s-1. It is shown that excited NO and possibly O2 molecules also contribute to the vibrationally stimulated ionization process. In a CO/Ar plasma, applying a dc bias to the cell electrodes resulted in the rapid accumulation of a deposit on the negative electrode due to a large cluster ion current. The average mass of an ion in this plasma, estimated by measuring the mass of the deposit, is m≅250 amu, which is consistent with the mass spectrometer analysis of the deposit. The deposit did not accumulate when small amounts of O2 and NO were added to the CO/Ar plasma, which presumably indicates the destruction of the cluster ions. It is demonstrated that adding small amounts of O2 to the optically pumped CO/Ar plasmas significantly increases the electron density, from ne = (4-7)×109 cm-3 to ne = (1-2)×1011 cm-3. This effect occurs at a nearly constant (within 50%) electron production rate S, indicating a substantial reduction in the overall electron removal rate. This reduction can be qualitatively interpreted as the destruction of rapidly recombining cluster ions in the presence of the O2 additive, and their replacement by monomer ions with a slower recombination rate. Further studies of the ion composition in optically pumped plasmas are suggested.

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“…Studies of vibrationally excited CO have been used to investigate dynamics in many condensed-phase systems, including CO dissolved in monatomic and diatomic liquids, , crystalline CO, organometallic complexes in solution containing CO bound to a single metal atom or a cluster of metal atoms, ,− CO bound to clean metal surfaces, − CO bound to heme proteins, ,,, and CO bound to model compounds …”

Section: Introductionmentioning

confidence: 99%

Vibrational Dynamics of Carbon Monoxide at the Active Sites of Mutant Heme Proteins

Hill¹,

Dlott²,

Rella

et al. 1996

J. Phys. Chem.

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Picosecond mid-IR pump-probe measurements of vibrational relaxation (VR) of CO bound to the active sites of wild-type and mutant myoglobins (Mb) reveal that an approximately linear relationship exists between the protein matrix-induced CO frequency shift and the VR rate. This relation parallels a similar linear relationship seen in a series of heme model compounds where Fe was replaced by Ru and Os. The VR rate of CO in the Mb is sensitive only to the magnitude of protein-induced carbonyl frequency shifts and apparently is not sensitive to the specific details of how the shift is induced, e.g., hydrogen bonding to CO or electrostatic interactions in the heme pocket. CO VR is insensitive to substantial changes in protein structure that do not affect the CO vibrational frequency. These observations suggest that the mechanism of carbon monoxide VR in heme proteins such as Mb occurs by through-π-bond anharmonic coupling, which, as shown in prior work, is also the dominant coupling in the model compounds. The experiments indicate that differing protein structures influence VR of CO bound at the active site not by opening and closing channels for vibrational energy flow from CO to the protein but by affecting the rate of energy flow from CO to heme. The rates are determined by the extent of back-bonding, which determines the magnitude of through-π-bond anharmonic coupling between CO and heme. The back-bonding and, therefore, the extent of anharmonic coupling are influenced by the electric fields in the heme pocket, which likely differ in the proteins studied here.

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Transfer and storage of vibrational energy in liquids: collisional up-pumping of carbon monoxide in liquid argon

Cited by 22 publications

References 6 publications

Vibrational Energy Relaxation and Spectral Diffusion in Water and Deuterated Water

Vibrational Energy Relaxation and Spectral Diffusion in Water and Deuterated Water

Ionization measurements in optically pumped discharges

Vibrational Dynamics of Carbon Monoxide at the Active Sites of Mutant Heme Proteins

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