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Physical Sciences and Mathematics Commons™
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- <p>Magnetostriction<br />Cadmium</p> (1)
- <p>Semiconductors -- Impurity distribution<br />Effective mass (Physics)</p> (1)
- Carbon monoxide<br />Molecular spectra<br />Photons (1)
- Elastic wave propagation<br />Elastic waves -- Mathematical models<br />Acoustic surface waves (1)
- Electromagnetic fields -- Permeability<br />Dielectric measurements<br />Filters and filtration<br />Infrared spectroscopy (1)
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- Helium ions<br />Electron energy loss spectroscopy (1)
- Liquids<br />Liquids -- Mathematical models<br />Lattice theory (1)
- Perovskite<br />Phase transformations (Statistical physics) (1)
- Surfaces (Physics)<br />Alkali metal halides<br />Thin films (1)
- Water vapor, Atmospheric<br />Atmospheric nucleation<br />Ionization of gases (1)
Articles 1 - 10 of 10
Full-Text Articles in Physical Sciences and Mathematics
Structures And Relationships Of Some Perovskite-Type Compounds, Christian Michel
Structures And Relationships Of Some Perovskite-Type Compounds, Christian Michel
Doctoral Dissertations
"A model for crystallographic transitions in perovskites is proposed. The model consists of regular octahedra sharing corners and topologically able to rotate without distortion around their three-fold axes. This model, with R3̄c symmetry (18e position) can be described in terms of a continuous rotation of angle, w, of octahedra from two ideal symmetry forms: the hexagonal close-packed and the cubic face-centered configurations. A parametric relation is derived between w and the rhombohedral cell angle, α, or the corresponding hexagonal axial ratio c/a . A wide range of atomic structures based on a framework of regular or slightly distorted octahedra sharing …
Radiative Lifetime Of The A¹Π State And The Transition Moment Variation Of The Fourth Positive Band System Of Carbon Monoxide, Joseph George Chervenak
Radiative Lifetime Of The A¹Π State And The Transition Moment Variation Of The Fourth Positive Band System Of Carbon Monoxide, Joseph George Chervenak
Doctoral Dissertations
"The lifetime of the A¹π state of carbon monoxide has been measured using a pulsed invertron excitation source and delayed coincidence measurement technique on the fourth positive system. Eighteen bands, originating from the upper states v' = 0 to 5, were examined at pressures between 500 and 50 microns, with no pressure dependence noted. The data were corrected for photon "pile up" and least-squares fitted to the sum of two exponentials. The transition moment was found to vary and was expanded about the r-centroid of the v' = 0 to v" = 0 transition. Oscillator strengths are calculated and compared …
Realistic Impulsive P Wave Source In An Infinite Elastic Medium, Joseph Hugo Hemmann
Realistic Impulsive P Wave Source In An Infinite Elastic Medium, Joseph Hugo Hemmann
Doctoral Dissertations
"The generally assumed instantaneous impulsive pressure sources for an elastic P wave in an infinite medium lead to basic contradictions, a step function source yielding infinite displacements as the shear modulus goes to zero, and the total energy radiated by a delta function (or any derivative of the delta function) source being infinite. By noting that the character of the solution in the elastic region must match the acoustic case near the source, a realistic impulsive pressure source is postulated which has a finite time history. The elastic field produced by this source is then obtained in closed form. A …
An Experimental And Theoretical Study Of The Nucleation Of Water Vapor On Ions In Helium And Argon, Daniel R. White
An Experimental And Theoretical Study Of The Nucleation Of Water Vapor On Ions In Helium And Argon, Daniel R. White
Doctoral Dissertations
"The nucleation of water vapor on ions in atmospheres of helium and argon was studied using an expansion type cloud chamber. Separation of the positive and negative ions was achieved so that the nucleation could be studied as a function of both the sign of the ionic charge and the supersaturation. A semiphenominological theory was developed as an extension of the classical theory to include the effects of the ionic charge on the nucleation process. The theoretical model of the prenucleation embryo was assumed to possess an oriented dipole surface layer with the direction of orientation dependent on the sign …
Absolute Excitation Cross Sections Of He⁺ In 20-100 Kev He⁺-He Collisions Using Energy-Loss Spectrometry, Donald Roy Schoonover
Absolute Excitation Cross Sections Of He⁺ In 20-100 Kev He⁺-He Collisions Using Energy-Loss Spectrometry, Donald Roy Schoonover
Doctoral Dissertations
"Application of positive-ion energy-loss spectrometry has been extended to include experimental determination of absolute excitation cross sections of ground state helium ions. Helium ion-atom collisions were studied for impact energies ranging between 20-100 keV, in 10 keV intervals. The data were taken with an apparatus resolution between 0.6-o.8 eV FWHM. Cross sections for transitions from ground state to the second and third principal quantum levels of the ion plotted as a function of impact energy were still rapidly increasing at 100 keV. The cross sections at this energy were 1.64(± 0.28) x 10⁻¹⁸cm² for He⁺(l²s1/2) -> He⁺(n = …
Investigation Into The Monotonic Magnetostriction And Magnetic Breakdown In Cadmium, James Milo Carter
Investigation Into The Monotonic Magnetostriction And Magnetic Breakdown In Cadmium, James Milo Carter
Doctoral Dissertations
"Observations of the monotonic magnetostriction of cadmium at 4.2 K and in fields of 65 kilogauss have been made. The angular dependence of an extremal point (Hm) in the monotonic magnetostriction is found to follow inverse cosine behavior. The magnitude of Hm (27 kG) for fields parallel to [0001] is in fair agreement with the onset of γ1/3 from the breakdown of the trifoliate orbit, γ. The range of observation of hm coincides with the reported range of the trifoliate orbit. A "klink" in the monotonic magnetostriction is demonstrated. The "klink" field, Hk, …
A Quasi-Lattice Model Of Simple Liquids, Jesse Herbert Collins
A Quasi-Lattice Model Of Simple Liquids, Jesse Herbert Collins
Doctoral Dissertations
"A cellular model of simple liquids is proposed which eliminates the objectionable feature of long range order found in other cell models. The volume is divided into N identical spherically symmetric cells, each occupied by one molecule. The cell-center density distribution relative to an average given cell center forms a series of Gaussian peaks whose width is proportional to the square root of the distance from the given cell center. The number of cell centers and average radial distance represented by each of the peaks correspond to a face-centered cubic lattice. The molecular pair distribution function is determined for several …
A Study Of Far Infrared Grid Filters, Harold Victor Romero
A Study Of Far Infrared Grid Filters, Harold Victor Romero
Doctoral Dissertations
"The diffraction theory for the transmission of electromagnetic fields through a grid in a dielectric is derived and experimentally checked in the visible wavelength region. In the far infrared, an approximate mathematical representation is found to describe the grids in dielectrics. The empirical equations in the far infrared are combined with the electrical circuit-transmission line analog for inductive grids. Detailed structure of the transmittance versus wave number curves are presented. Then the theory of multielement grid filters is derived and compared with experiment. The properties of the filters can be predicted from a knowledge of the characteristics of the individual …
Theory Of Shallow Donor Impurity Surface States, Vidal Emmanuel Godwin
Theory Of Shallow Donor Impurity Surface States, Vidal Emmanuel Godwin
Doctoral Dissertations
"A variational approach has been used to solve the effective-mass equation, when the impurity ion is located at a depth d from the surface of a semiconductor, where 0 < d < db and db represents the case when the impurity ion is in the bulk of the semiconductor. The ground state and the excited state having the largest electric dipole coupling to the ground state have been determined. We have plotted the energy dependence on the depth of the impurity ion from the surface of the semiconductor. The energy has also been calculated as a function of the orientation of the …
The Surface Effects Of Alkali Halides In The Infrared, Vincent Joseph Llamas
The Surface Effects Of Alkali Halides In The Infrared, Vincent Joseph Llamas
Doctoral Dissertations
"The surface state extension of the shallow donor theory is reviewed. The surface state theory and its applications to F-centers of alkali halides is presented. Experimental infrared data show an absorption which seems to correspond with the ground state to first excited state transition. Surface state concentrations of F-centers as a function of depth into the crystal are given. The ratio of surface to bulk cross sections in KBr and experimental calculations of effective masses in various alkali halides are in excellent agreement with theory. The theoretical cross sections are derived from transition probabilities. However, lack of excited states, the …