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Mechanisms And Dynamics Of The Metastable Decay In Ar-2(+), J. Fedor, K. Gluch, R. Parajuli, S. Matt-Leubner, Olof E. Echt, P. Scheier, T. D. Mark

Physics & Astronomy

A detailed experimental as well as theoretical investigation of the properties of the metastable dissociation Ar-2(+)-->Ar++Ar is presented. The mass-analyzed ion kinetic energy (MIKE) scan technique has been performed using a three sector field mass spectrometer. The possible mechanisms of the metastability of Ar-2(+) have been examined and the observed decay process is assigned to the II(1/2)(u)-->I(1/2)(g) bound to continuum radiative transition, in agreement with earlier work. The calculation of the theoretical shape of the kinetic energy release distribution of fragment ions allowed us to construct the theoretical MIKE peak and compare it with the raw experimental data. …

High-Resolution Kinetic Energy Release Distributions And Dissociation Energies For Fullerene Ions C(N)(+), 42 <= N <= 90, K. Gluch, S. Matt-Leubner, Olof E. Echt, B. Concina, P. Scheier, T. D. Mark

Physics & Astronomy

We have measured the kinetic energy released in the unimolecular dissociation of fullerene ions, C(n)(+)-->C(n-2)(+)+C(2), for sizes 42less than or equal tonless than or equal to90. A three-sector-field mass spectrometer equipped with two electric sectors has been used in order to ensure that contributions from isotopomers of different masses do not distort the experimental kinetic energy release distributions. We apply the concept of microcanonical temperature to derive from these data the dissociation energies of fullerene cations. They are converted to dissociation energies of neutral fullerenes with help of published adiabatic ionization energies. The results are compared with literature values. …

High Resolution Measurements Of Kinetic Energy Release Distributions Of Neon, Argon, And Krypton Cluster Ions Using A Three Sector Field Mass Spectrometer, K. Gluch, S. Matt-Leubner, L. Michalak, Olof E. Echt, A. Stamatovic, P. Scheier, T. D. Mark

Physics & Astronomy

Using a newly constructed three sector field mass spectrometer (resulting in a BE1E2 field configuration) we have measured the kinetic energy release distributions of neon, argon, and krypton cluster ions. In the present study we used the first two sectors, B and E1, constituting a high resolution mass spectrometer, to select the parent ions in terms of mass, charge, and energy, and studied the decay of those ions in the third field free region. Due to the improved mass resolution we were able to extend earlier studies carried out with a two sector field machine, where an upper size limit …

Beam Spin Asymmetry Measurements In Deeply Virtual Compton Scattering, Gagik Gavalian

Doctoral Dissertations

Beam Spin Asymmetry (BSA) is studied in the Deeply Virtual Compton Scattering (DVCS) using CLAS detector at Jefferson Lab and longitudinally polarized electron beam with 4.8 GeV energy. This asymmetry is directly proportional to the imaginary part of the scattering amplitude, which relates it to the Generalized Parton distribution functions. Reaction ep → epX is studied. A fit to the line shape of the missing mass squared distribution of (ep) is used to extract the number of single photon final states in each kinematical bin for both helicities of the beam and for the helicity sum. DVCS beam spin asymmetry …

Sounding Rocket Measurements Of Thermal Electrons In Active Nightside Aurora, Elizabeth Macdonald

Doctoral Dissertations

On January 14th 2002 the SIERRA sounding rocket was launched from Poker Flat Research Range, Alaska into active substorm expansion aurora and reached 735 km. For the first time, direct measurements of the cold ionospheric population in darkness were made by the UNH Thermal Electron Detector (TED). At these middle altitudes, understanding this population is important because the thermal electrons can carry currents coupling the lower ionosphere and the magnetospheric auroral source. This thesis, focusing on the development and analysis of this new instrument, incorporates the study of two distinct areas. One area is the direct measurement of the ambient …

On The Rayleigh -Brillouin Scattering In Air, Qiuhua Zheng

Doctoral Dissertations

GroundWinds lidar system is a high-spectral-resolution lidar system that can directly measure the Rayleigh-Brillouin scattering (RBS) spectra, from which the wind, temperature, and turbulence in the troposphere can be measured. Its transmitter is a double-frequency Nd-YAG laser at 532nm. Most of the data used in this research were taken on 31 July 2002.

A widely used mathematic model---the S6 model---is fitted to the measured RBS spectra. The discrepancies between the measured temperature from the RayleighBrillouin spectra and from the radiosonde, combined with the discrepancies between the model and the measured RBS spectra, indicate that there is room for the S6 …