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in subjects: "Vibrational States"

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Hierarchical analysis of molecular spectra

A novel representation of molecular spectra in terms of hierarchical trees has proven to be an important aid for the study of many significant problems in gas-phase chemical dynamics. Trees are generated from molecular spectra by monitoring the changes that occur in a spectrum as resolution is changed in a continuous manner. A tree defines a genealogy among all lines of a spectrum. This allows for a detailed understanding of the assignment of features of a spectrum that may be difficult to obta… more

Date: March 1, 1996

Creator: Davis, M.J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Optical spectroscopy of a nitrogen-hydrogen complex in ZnSe

We have observed two local vibrational modes related to H bonded to N acceptors in ZnSe samples. grown by metal organic vapor phase epitaxy. The modes have been seen in both infrared and Raman spectroscopy. The new mode seen at 3194 cm{sup {minus}1} is assigned to an N-H stretching vibrational mode and the mode found at 783 cm{sup {minus}1} is tentatively assigned to an N-H wagging, vibrational mode. Polarized Raman spectroscopy was used to determine that the symmetry of the defect complex is C… more

Date: February 1, 1994

Creator: Wolk, J. A.; Ager, J. W., III; Duxstad, K. J.; Haller, E. E.; Taskar, N. R.; Dorman, D. R. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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The photodissociation and reaction dynamics of vibrationally excited molecules. Technical progress report, 1993--1994

Combined vibrational overtone excitation and laser induced fluorescence detection was used to study dissociation dynamics of hydroxylamine (NH{sub 2}OH), laser induced grating experiments on water were analyzed, discovering the important role that electrostriction and thermal relaxation play, and a new apparatus for preparing vibrationally excited molecules with simulated Raman excitation was completed and the first measurements made. Role of vibrational excitation in photodissociation dynamics… more

Date: April 1, 1994

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Molecule-cluster collisions: Reaction of D{sub 2} with Ni{sub 13}

The reactive channel (dissociative adsorption of the molecule on the cluster) of the D{sub 2} + Ni{sub 13} collision system is studied via quasiclassical molecular dynamics simulations. The effects of the initial rovibrational state of the molecule and of the cluster structure are examined. Pronounced mode-selectivity of the reaction and a strong structure-reactivity correlation are found. A technique to analyze cluster-molecule complex (``resonance``) formation is presented and used to charact… more

Date: December 31, 1991

Creator: Jellinek, Julius & Guevenc, Ziya B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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A Nonlocal Model of Dissociative Electron Attachment andVibrational Excitation of NO

We present the results of a study of elastic scattering and vibrational excitation of NO by electron impact in the low-energy (0-2eV) region where the cross sections are dominated by resonance contributions. The {sup 3}{Sigma}{sup -}, {sup 1}{Delta} and {sup 1}{Sigma}{sup +} NO{sup -} resonance lifetimes are taken from our earlier study [Phys. Rev. A 69, 062711(2004)], but the resonance energies used here are obtained from new configuration-interaction studies. Here we employ a more elaborate n… more

Date: January 1, 2005

Creator: Trevisan, Cynthia S.; Houfek, Karel; Zhang, Z.; Orel, Ann E.; McCurdy, C. William & Rescigno, Thomas N.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Isotope, Electric Field, and Vibrational State Dependence of Single Rotational Level Lifetimes of S1 Formaldehyde

Additional single rovibronic level lifetimes of S{sub 1} H{sub 2}CO and D{sub 2}CO have been measured under collisionless conditions. The H{sub 2}CO 4{sup 1} lifetimes vary at least a factor of 150, from 20 nsec to 3.10 {micro}sec. The observed D{sub 2}CO 4{sup 1} lifetimes fluctuate about {+-} 20% around a mean value of 6.2 {micro}sec, which is probably close to the pure radiative lifetime. In contrast, the observed D{sub 2}CO 4{sup 3} lifetimes vary from 1.09 to 2.46 {micro}sec and the 2{sup … more

Date: December 1, 1979

Creator: Weisshaar, James C. & Moore, C. Bradley

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Two interesting features in the infrared and raman spectra of the 12K organic superconductor {chi}-(ET){sub 2}Cu[N(CN){sub 2}]Br

Two of the larger features in the infrared conductivity spectra of {chi}-(ET){sub 2}Cu[N(CN){sub 2}]Br are analyzed and one is reassigned with the aid of infrared and Raman spectra of isotopically substituted compounds.

Date: December 31, 1995

Creator: Eldridge, J. E.; Xie, Y.; Wang, H. H.; Williams, J. M.; Kini, A. M. & Schlueter, J. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Vibrational spectroscopy of water interfaces

The second order nonlinear optical processes of second harmonic generation and sum frequency generation are powerful and versatile tools for studying all kinds of surfaces. They possess unusual surface sensitivity due to the symmetry properties of the second order nonlinear susceptibility. The technique of infrared-visible sum frequency generation (SFG) is particularly attractive because it offers a viable way to do vibrational spectroscopy on any surfaces accessible to light with submonolayer … more

Date: December 1, 1994

Creator: Du, Q.

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

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Vibration-rotation-tunneling dynamics in small water clusters

The goal of this work is to characterize the intermolecular vibrations of small water clusters. Using tunable far infrared laser absorption spectroscopy, large amplitude vibration-rotation-tunneling (VRT) dynamics in vibrationally excited states of the water dimer and the water trimer are investigated. This study begins with the measurement of 12 VRT subbands, consisting of approximately 230 transitions, which are assigned to an 82.6 cm{sup {minus}1} intermolecular vibration of the water dimer-… more

Date: November 1, 1992

Creator: Pugliano, N.

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

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Low frequency dynamics of CO/Cu-breakdown of Born-Oppenheimer approximation

Synchrotron infrared studies of adsorbates on surfaces offer the possibility of probing low frequency vibrational modes and dynamics at high resolution (1 cm{sup {minus}1}, 125 {mu}eV). Extensive experiments have been performed for ordered submonolayers of CO on low index Cu surfaces [({radical}3 {times} {radical}3)R30{degree} CO/Cu(1ll), c(2 {times} 2) CO/Cu(100) and (1 {times} 2) CO/Cu(l10)], in the 100-2500 cm{sup {minus}1} ({approximately}12.5 {minus} 312.5 MeV) range. These are the first I… more

Date: December 31, 1993

Creator: Hirschmugl, C.; Williams, G. P.; Chabal, Y. J. & Hoffmann, F. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Kinetics of an H$sub 2$--F$sub 2$ explosion as initiated by a pulse of fluorine atoms

The elementary reactions occurring in an H/sub 2/-F/sub 2/ explosion are given with each vibrational level of H/sub 2/ and HF considered as a separate reacting species. Rate coefficients for all the elementary reactions are either estimated or calculated, and the major assumptions entering into the determination of each rate coefficient are given. The effect of non-Maxwell distributions in the translational energies of some of the species is estimated. For strong pulses of F atoms, the explosio… more

Date: February 1, 1974

Creator: Sullivan, John H. & Feber, Roy C.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Direct observation of infrared free induction decay of liquid water molecules with a femtosecond OPO at 3 micron

The infrared vibrational quantum beats of solution phase water molecules are directly observed at room temperature by up-coverting the free induction decay generated with a femtosecond optical parametric oscilator.

Date: May 1, 1994

Creator: Crowell, R. A.; Holtom, G. R. & Xie, S. X.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Quantum phase space theory for the calculation of v{center_dot}j vector correlations

The quantum state-counting phase space theory commonly used to describe barrierless dissociation is recast in a helicity basis to calculate photofragment v{center_dot}j correlations. Counting pairs of fragment states with specific angular momentum projection numbers on the relative velocity provides a simple connection between angular momentum conservation and the v{center_dot}j correlation, which is not so evident in the conventional basis for phase space state counts. The upper bound on the o… more

Date: July 1, 1995

Creator: Hall, G. E.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Crossed molecular beams study of O({sup 1}D) reactions with H{sub 2} molecules

Reaction dynamics of O({sup 1}D) atoms with H{sub 2} molecules was reinvestigated using the crossed molecular beams technique with pulsed beams. The O({sup 1}D) beam was generated by photodissociating O{sub 3} molecules at 248 nm. Time-of-flight spectra and the laboratory angular distribution of the OH products were measured. The derived OH product center-of-mass flux-velocity contour diagram shows more backward scattered intensity with respect to the O({sup 1}D) beam. In contrast to previous s… more

Date: May 1, 1995

Creator: Miau, T.T.

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

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Highly excited molecular spectra. Progress report, January 1, 1992--December 31, 1992

Goal is to devise new methods to analyze spectra and dynamics of highly excited vibrational states of molecules. Strong mode coupling and anharmonicity give rise to complicated classical dynamics, making the simple normal mode analysis unsatisfactory. New methods of spectral analysis, pattern recognition, and assignment are sought using techniques of nonlinear dynamics including bifurcation theory, phase space classification, and quantization of phase space structures. Emphasis in the past year… more

Date: December 31, 1992

Creator: Kellman, M. E.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Interaction of highly vibrationally excited molecules with clean metal surfaces. Final technical report

The authors present results from a grant funded under the Department of Energy Office of Basic Energy Sciences. A collaboration between Prof. Alec Wodtke of the Department of Chemistry at UCSB and Daniel J. Auerbach of IBM Almaden Research Labs has allowed new experiments on the dynamics of surface chemical reactivity to be successfully executed. High quality data has been generated which provides an excellent test of theoretical models of surface reactivity, a topic of importance to catalysis.… more

Date: November 1, 1998

Creator: Wodtke, A. M. & Auerbach, D. J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Thermodynamic properties for polycyclic systems by non-calorimetric methods. Progress report, August 1, 1992--September 30, 1993

A detailed vibrational spectroscopic study of furan, pyrrole, and thiophene has been completed. These compounds form part of the base of five-membered ring systems on which the rest of the research program will be built Several methyl-substituted derivatives were also studied. The results will be used to confirm the model for alkyl- substitution in the ring systems. Gas-phase spectra and fundamental- frequency assignments were completed for 2,3- and 2,5-dihydrofuran. Those compounds initiate wo… more

Date: March 1, 1993

Creator: Steele, W. V.; Chirico, R. D. & Klots, T. D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Time-Resolved Infrared Absorption Studies Applied to the Study of Radical Plus Molecule Reactions

Reaction of the cyano radical (CN) with ethane (C{sub 2}H{sub 6}) was studied using time resolved infrared absorption to monitor the product hydrogen cyanide (HCN) in individual to-vibrational states. Pulse laser photolysis was used to provide an initial excess of the CN radical and the time dependence of individual ro-vibrational states of the high frequency anti-symmetric stretching mode of HCN (0,0,v{sub 3}) was followed. These experiments reveal that the initial product state distribution o… more

Date: February 1, 1994

Creator: Bethardy, G. A.; Macdonald, R. G. & Northrup, F. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Ultraviolet Absorption Spectrum of Nitrous Oxide as Function of Temperature and Isotopic Substitution

The ultraviolet absorption spectra of nitrous oxide and its {sup 15}N isotopes over the wavelength range 197 to 172 nm and between 150 and 500 K show a weak continuous absorption and a pattern of diffuse banding that became pronounced at higher temperatures. The temperature dependence of the absorption spectrum results from the activation of the n{sub 2}{double_prime} bending mode. Deconvolution of the data shows that absorption by molecules in the (010) vibrational mode results in a spectrum o… more

Date: July 1, 1980

Creator: Selwyn, G. S. & Johnston, H. S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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An experimental and density functional theory study of the interactions of CH4 with H-ZSM-5

The interactions of methane with Bronsted acid sites in H-ZSM-5 were investigated both experimentally and theoretically. Diffuse reflectance infrared spectroscopy was used to acquire spectra for methane adsorbed on H-ZSM-5 at room temperature and at 77 K. Upon adsorption, the v1 and v3 vibrational bands of methane shift by -15 and -23 cm-1, respectively, and the vibrational band for OH groups associated with Bronsted acid sites shifts by -93 cm-1. Quantum chemical calculations conducted at the … more

Date: August 25, 2001

Creator: Khaliullin, Rustam Z.; Bell, Alexis T. & Kazansky, Vladimir B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Use of the 7.6 MeV {sup 16}O({alpha},{alpha}) resonance in studying the anomalous channeling behavior of Yba{sub 2}Cu{sub 3}O{sub 7-x} near T{sub c}

By using the intense {sup 16}O ({sup 4}He,{sup 4}He) elastic scattering resonance at 7.3--7.6 MeV, we have been able to extend the earlier investigations of the channeling behaviour in YBa{sub 2}Cu{sub 3}O{sub 7-x} around T{sub c} to include the backscattered signal from the oxygen sublattice. We have also developed a computer code enabling us to simulate c-axis angular scans for each atomic sublattice as a function of depth. These simulations reproduce very well the observed oxygen angular sca… more

Date: June 1, 1995

Creator: Andersen, J. U.; Ball, G. C. & Davies, J. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Inelastic Neutron Scattering From Amorphous Germanium

No Description Available.

Date: January 1, 1974

Creator: Axe, J. D.; Keating, D. T.; Cargill, G. S., III & Alben, R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Infrared Heating of Hydrogen Layers in Hohlraums

The authors report results of modeling and experiments on infrared heated deuterium-hydride (HD) layers in hohlraums. A 2 mm diameter, 40 {micro}m thick shell with 100-400 {micro}m thick HD ice inside a NIF scale-1 gold hohlraum with 1-3 {micro}m rms surface roughness is heated by pumping the HD vibrational bands. Models indicate control of the low-mode layer shape by adjusting the infrared distribution along the hohlraum walls. They have experimentally demonstrated control of the layer symmetr… more

Date: August 15, 2001

Creator: Kozioziemski, B J; McEachern, R L; London, R A & Bitter, D N

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Hydrogen vibrational density of states of adsorbed water on rare-earth modified zirconia

Rare-earth (RE) doped ZrO{sub 2} prepared by a method of coprecipitation from aqueous solution shows many properties such as good thermal stability and large surface area ({approximately}80 m{sup 2}/g) that are suitable for use as catalyst supports and sorbents for a variety of molecules. The authors have measured the vibrational densities of states of surface hydroxyl groups as well as physisorbed water molecules in La{sub 0.1}Zr{sub 0.9}O{sub 1.95} and Nd{sub 0.1}Zr{sub 0.9}O{sub 1.95} by ine… more

Date: July 20, 1994

Creator: Loong, C. K.; Iton, L. E. & Ozawa, Masakuni

Item Type: Article

Partner: UNT Libraries Government Documents Department