Large Amount Of Vibrational Energy Research Articles

Blood loss and Procedure Time in Major Salivary Glands Benign Tumors Resection Using Harmonic Scalpel

Ultrasonic vibration is mainly used in minimally invasive surgery since it uses longitudinal mechanical waves with the ability to propagate in a solid and liquid medium, conducted to the tissues through an active tip, a large amount of vibrational energy is produced at the point of contact getting the section, coagulation and dissection of tissue. Objective. To evaluate the operating time and blood loss in major salivary glands benign tumors resection using harmonic scalpel during the period from August 2018 to March 2019 at the Dr. Darío Fernández General Hospital. Material and methods. Twelve patients with benign salivary gland tumors of both sexes between 39 and 76 years of age were included for the study, time and intraoperative bleeding were quantified and analyzed with measures of central tendency. Results: The most frequently performed surgery was submaxilectomy (50%), followed by superficial parotidectomy (33.3%) and submaxilectomy plus lymph node resection (16.6%). The intraoperative time lasted from 20 to 65 minutes with an average 44.16 minutes, bleeding in milliliters ranged from 25 to 60 milliliters with a mean of 42. 9 ml. Conclusions: The use of ultrasonic vibration significantly reduces operating time and blood loss due to coagulation and cutting simultaneously with less heat production.

NO Vibrational Energy Transfer on a Metal Surface: Still a Challenge to First-Principles Theory

During a collision of highly vibrationally excited NO with a Au(111) surface, the molecule can lose a large fraction of its vibrational energy into electronic excitation of the metal. This process violates the Born–Oppenheimer approximation and represents a major challenge to theories of molecule–surface interaction. Two ab initio approaches to this problem, one using independent electron surface hopping (IESH) and the other electronic friction, previously reported good agreement with the limited available data on multiquantum vibrational relaxation; however, at that time only experiments for NO(vi = 15) at an incidence translational energy of Ei = 0.05 eV were available. In this work, we report a comparison of recently reported experiments characterizing the multiquantum vibrational relaxation of NO on Au(111) for a wider range of incidence translational and vibrational energies to IESH and molecular dynamics with electronic friction (MDEF) calculations for these conditions. Both theories fail to explain the large amount of vibrational energy transferred from NO to the solid.

Photoionization of tris(2-phenylpyridine)iridium

The photoionization of gas-phase tris(2-phenylpyridine)iridium (Ir(ppy)3) has been examined. One- and two-photon studies yield a conservative estimate for the upper bound to the ionization energy of 6.4 eV. The one-photon experiment used 193 nm radiation. The latter experiments used tunable UV radiation to excite the ligand-centered 1LC state, which is followed by radiationless decay and photoionization. An accompanying paper presents a theoretical study of excited singlets and triplets and low-energy states of . The calculated ionization energy is ∼5.9 eV. The experimental and calculated results together indicate an ionization energy of ∼6 eV. An undulation in the ion yield spectrum (∼270 cm−1 spacing) was observed. It is due to structure in the transition that originates from T1, which is populated through radiationless decay of 1LC. At low fluence, is produced without fragmentation, despite the fact that a large amount of vibrational energy is present in T1. Specifically, this vibrational energy is the sum of and the thermal energy due to the 177 Ir(ppy)3 vibrational degrees of freedom at 500 K, i.e. the temperature at which the experiments were carried out. This vibrational energy is transported efficiently to the cation.

Electronic structure of tris(2-phenylpyridine)iridium: electronically excited and ionized states

A computational study of tris(2-phenylpyridine)iridium, Ir(ppy)3, is presented. The perspective is that of using organo-transition-metal complexes as phosphorescent species in light-emitting diodes (OLED's). Quantum yields approaching 100% are possible through a triplet harvesting mechanism. Complexes such as Ir(ppy)3 are amenable to exacting experimental and theoretical studies: small enough to accommodate rigor, yet large enough to support bulk phenomena in a range of host materials. The facial and meridional isomers differ by ∼220 meV, with fac-Ir(ppy)3 having the lower energy. Because fac-Ir(ppy)3 dominates in most environments, focus is on this species. Time-dependent density functional theory using long-range-corrected functionals (BNL and ωB97X) is used to calculate excited states of Ir(ppy)3 and a few low energy states of . The calculated T1 – S0 energy gap (2.30 eV) is in reasonable agreement with the experimental value of 2.44 eV. Only a few percent of singlet character in T1 is needed to explain so short a phosphorescence lifetime as 200 ns, because of the large and absorption cross-sections. Equilibrium geometries are calculated for S0, T1, and the lowest cation state (D0), and several ionization energies are obtained: adiabatic (5.86 eV); vertical from the S0 equilibrium geometry (5.88 eV); and vertical ionization of T1 at its equilibrium geometry (5.87 eV). These agree with a calculation by Hay (5.94 eV), and with the conservative experimental upper bound of 6.4 eV. Molecular orbitals provide qualitative explanations. A calculated UV absorption spectrum, in which transitions are vertical from the S0 equilibrium geometry, agrees with the room temperature experimental spectrum. This is consistent with Franck–Condon factors dominated by , as expected given the delocalized nature of the orbitals. Ir(ppy)3 vibrational frequencies were calculated and used to estimate the probability density for 500 K, i.e. the temperature at which the experiments were carried out. In combination with the vibrational energy imparted through photoexcitation, it is seen that a large amount of vibrational energy appears in without causing its fragmentation. Specifically, for = 15,000 cm−1, the probability density for total vibrational energy peaks at ∼31,000 cm−1 with a 7800 cm−1 width.

Hydrogen-Bond Disruption by Vibrational Excitations in Water

An excitation of the OH-stretch nu(OH) of water has unique disruptive effects on the local hydrogen bonding. The disruption is not an immediate vibrational predissociation, which is frequently the case with hydrogen-bonded clusters, but instead is a delayed disruption caused by a burst of energy from a vibrationally excited water molecule. The disruptive effects are the result of a fragile hydrogen-bonding network subjected to a large amount of vibrational energy released in a short time by the relaxation of nu(OH) stretching and delta(H2O) bending excitations. The energy of a single nu(OH) vibration distributed over one, two, or three (classical) water molecules would be enough to raise the local temperature to 1100, 700, or 570 K, respectively. Our understanding of the properties of the metastable water state having this excess energy in nearby hydrogen bonds, termed H2O*, has emerged as a result of experiments where a femtosecond IR pulse is used to pump nu(OH), which is probed by either Raman or IR spectroscopy. These experiments show that the H2O* spectrum is blue-shifted and narrowed, and the spectrum looks very much like supercritical water at approximately 600 K, which is consistent with the temperature estimates above. The H2O* is created within approximately 400 fs after nu(OH) excitation, and it relaxes with an 0.8 ps lifetime by re-formation of the disrupted hydrogen-bond network. Vibrationally excited H2O* with one quantum of excitation in the stretching mode has the same 0.8 ps lifetime, suggesting it also relaxes by hydrogen-bond re-formation.

Collision-induced annealing of octanethiol self-assembled monolayers by high-kinetic-energy xenon atoms

Collisions with high-energy xenon atoms (1.3 eV) induce structural changes in octanethiol self-assembled monolayers on Au(111). These changes are characterized at the molecular scale using an in situ scanning tunneling microscope. Gas-surface collisions induce three types of structural transformations: domain boundary annealing, vacancy island diffusion, and phase changes. Collision-induced changes that occur tend to increase order and create more stable structures on the surface. We propose a mechanism where monolayer transformations are driven by large amounts of vibrational energy localized in the alkanethiol molecules. Because we monitor incremental changes over small regions of the surface, we can obtain structural information about octanethiol monolayers that cannot be observed directly in scanning tunneling microscopy images.

White-light-induced fragmentation of toluene.

We investigate the influence of continuum generation on the photofragmentation dynamics of the toluene molecule. By sending an 80-fs Ti:sapphire laser beam through a 2-mm-thick CaF2 plate we show that even moderately broadened laser frequency spectra considerably increase the degree of fragmentation, while it is nearly absent without continuum generation. The measured broadening of the frequency spectra and the known Raman-active vibrational modes of toluene afford an explanation in terms of a stimulated Raman scattering scheme, in which the molecule absorbs large amounts of vibrational energy.

Multiple Roles of Highly Vibrationally Excited Molecules in the Reaction Zones of Detonation Waves

Recent experimental and theoretical advances in the understanding of high-pressure, high-temperature chemical kinetics are used to extend the nonequilibrium Zeldovich−von Neumann−Doring (NEZND) theory of self-sustaining detonation in liquid and solid explosives. The attainment of vibrational equilibrium behind the leading shock front by multiphonon up-pumping and internal vibrational energy redistribution establishes a high-temperature, high-density transition state or series of transition states through which the chemical decomposition proceeds. The reaction rate constants for the initial unimolecular decomposition steps are accurately calculated using high-temperature, high-density transition-state theory. These early reactions are endothermic or weakly exothermic, but they channel most of the available energy into excited vibrational states of intermediate product species. The intermediate products transfer some of their vibrational energy back into the transition states, accelerating the overall reaction rates. As the decomposition progresses, the highly vibrationally excited diatomic and triatomic molecules formed in very exothermic chain reactions are rapidly vibrationally equilibrated by “supercollisions”, which transfer large amounts of vibrational energy between these molecules. Along with vibrational−rotational and vibrational−translational energy transfer, these excited vibrational modes relax to thermal equilibrium by amplifying pressure wavelets of certain frequencies. These wavelets then propagate to the leading shock front and reinforce it. This is the physical mechanism by which the leading shock front is sustained by the chemical energy release.

Decomposition of highly vibrationally excited CDCl3

Decomposition of highly vibrationally excited CDCl3 was studied in the time domain by measuring laser-induced fluorescence from one of the decomposition products CCl2 or by observing luminescence from CCl2 radical fragments produced in the Ã(1B1) state following IR excitation. It is shown that highly vibrationally excited CDCl3 can be made via two different routes: i/mple optical absorption of an incident 13CO2 laser pulse or through collision-moderated energy pooling coupled with photon absorption. Higher fluence measurements are consistent with the former and support previous claims that the infrared multiphoton decomposition probability for CDCl3 is pressure independent. At a lower fluence the vibrational up-pumping mechanism apparently relies heavily upon collisions, which supports other claims that the decomposition probability is pressure dependent. The results of the present work reconcile these previous disparate claims. Furthermore, there is an indication that the vibrational energy transferred during a collision could be much larger than collision-induced dipole selection rules would allow. In some of the experiments, electronically excited CCl2 fragments are created but only through post-laser-pulse collisions that appear to involve exchanges of very large amounts of vibrational energy. By contrast, no electronically excited CCl2 is produced following excitation with the CO2 laser alone. The experiments also corroborate an earlier prediction that the extent of reaction is governed by adiabatic expansion of the centrally heated zone, even at pressures as low as 0.66 kPa, rather than by diffusion, as is commonly believed.

Observation of highly energetic collisions in classical trajectory studies of collisional energy transfer

The importance of collisions transferring large amounts of vibrational energy to and from highly vibrationally excited molecules is studied. In single collisions of hot CS{sub 2} with different collision partners (CO, Ar, HCl, CH{sub 4}) up to 40 kcal/mol can be transferred. The relative importance of such supercollisions is small, but they can be observed in several phenomena. The authors show that the largest energy transfer does not correlate directly with either the initial CS{sub 2} energy for low-order moments of the vibrational energy transfer distribution.

UV multiphoton excitation: An access to the energy dependence of unimolecular reactions and collisional energy transfer

Repetitive absorption of UV (or visible) photons followed by fast internal conversions allows to deposit large amounts of vibrational energy in polyatomic molecules. Intra- and intermolecular processes with relatively weak energy dependences can be studied by this excitation over broad energy ranges. The technique is illustrated for the unimolecular isomerization azulene → naphthalene and collisional energy transfer of vibrationally excited azulene. With ns excimer laser pulses, up to three photons at λ=308 nm were deposited in the molecule, and collisional quenching competing with isomerization was studied. The results can be modeled conveniently by a multistep mechanism.

Microslip and macroslip in bolted joints

The dynamic forces which occur in structures whose jointed parts may slide during dynamic loading are associated with energy dissipation. The high-strength friction grip bolted joint (HSFGBJ) is a structural element which under certain circumstances may dissipate a large amount of vibrational energy. This energy is an increasing function of the frictional force and of the magnitude of slip of the joint. However, in a joint with a relatively large number of bolts, the amount of slip cannot be large, as the bolt holes are not much larger than the bolt diameter. Thus, some bolts of the joint may be sheared at the beginning of the full-slip stage of loading. In this paper, mathematical equations for the frictional force and slip in both stages of loading—partial slip and full slip—are established, and the dissipation of energy is evaluated. It is shown that if the joint is designed so that the magnitude of slip is at the border partial slip/full slip, the joint may dissipate a large amount of vibrational energy.

Investigation of the oxidation of carbon disulfide in gas flows using ir spectroscopy

The oxidation of carbon disulfide has been intensively studied recently because the carbon monoxide molecules formed during the chemical reaction have a large amount of vibrational energy and can be used to create laser media. Previously, studies have been made of the IR emission from a carbon disulfide flame and the dependence of the intensoty of emission from CO and CO/sub 2/ molecules on the stoichiometric ratio between the oxide and fuel concentrations has been found. In this paper the authors present the results from a spectroscopic study of the emission from a flame in the near infrared. The purpose of this work is to compare the spectra of carbon disulfide flames in different mixtures as well as to find the dependence of their shape on the pressure of the medium for a more detailed study of the effect of chemical and vibrational kinetics on the emission from CO molecules.

Vibrational and electronic excitation in p-benzoquinone by electron impact

Vibrational and electronic excitation by electron impact in p-benzoquinone was studied using a trochoidal electron spectrometer. Two distinct patterns of vibrational excitation were observed. First, low quanta of a few selected vibrations are specifically excited at incident electron energies corresponding to shape resonances. Some resonances excite mainly the CO stretch, others the CH stretch vibration, and this selectivity is used in the discussion of the assignment of the resonances. A second pattern is an unspecific excitation of a quasi-continuum where no structure due to individual vibrational levels can be discerned. This feature peaks at threshold, large amounts of vibrational energy can be deposited in the molecule, and the excitation also proceeds via shape resonances. Electronic excitation spectra in the valence and Rydberg regions are also presented and discussed. A band observed at 4.37 eV with low residual energies has been tentatively assigned to the second π — π* triplet state 3B3g.

Collisional deactivation of laser excited singlet molecular oxygen by ozone

The effect of small amounts of ozone (5–38 mm) on the rate of collisional deactivation of singlet molecular oxygen O2(1Δg) excited by means of laser radiation at 1.064 μ has been investigated. Due to the fact that high oxygen pressures were used (35 atm), the rate of deactivation of O2(1Δg) by collision with ground electronic state oxygen O2(3Σ−g) competes with deactivation by O3, a situation not encountered by previous investigators at much lower pressures. In the case of minimum O3 partial pressure (5 mm), the effect of O3 in direct deactivation of O2(1Δg) is negligible, with the controlling process being an intersystem crossing (electronic–vibration) O2(1Δg)(v′=0) →O2(3Σ−g)(v=5). Analysis of the data indicates that transfer of this large amount of vibrational energy to O3 en bloc must take place with high efficiency, producing O3 in a highly excited vibrational state lying just below the dissociation limit. Dependence of the overall deactivation rate of O2(1Δg) on O3 partial pressure exhibits a quadratic term in addition to the linear variation observed by other investigators at lower pressures. The effect of adding a third component (He, SO2, CO2, and NO2) with the ozone partial pressure held constant was also studied.

Inelastic scattering of vibrationally excited KBr by small nonpolar and essentially nonpolar partners

Scattering intensities as functions of angle and velocity, for the interaction of highly vibrationally excited potassium bromide with neon, argon, nitrogen, carbon dioxide, and carbon monoxide under molecular beam conditions, are. reported. Long range attractive forces are of relatively little importance in these systems; energy transfer proceeds through essentially impulsive interactions. Inelastic collisions transferring large amounts of vibrational energy into translation occur with cross sections on the order of 20Å 2. Effects due to competition between V → V and V → T processes are clearly present in some systems.