Elementary Electron Research Articles

3-D period doubling and magnetic moments of particles

Several invariant properties of matter seem to fit remarkably well to quantized values obtained from Planck domain units by period doubling in three dimensions. The units are defined using natural constants only. Such properties include the elementary electric charge, electron and proton rest energies and others. It has been shown by W. G. Tifft that the quantized redshifts of galaxies fit the pattern, too. Magnetic moments of the electron, proton, neutron, muon and lambda particles also seem to obey the doubling rule. The same number of doublings seems to yield the electron and proton rest masses and magnetic moments correspondingly. The proton rest mass is E0×2−64 and the magnetic moment µ o × 264, where E0 and µ o are the Planck domain units. The corresponding exponent of 2 for the electron is 75.66. The units for the proton and the electron differ by a factor of\(\sqrt \pi \). The magnetic moment of the muon suggests a close relationship between the magnetic structures of the muon and the proton, whereas the lambda particle seems to be related to the neutron. Reasons for the supposed existence of quantized 3-d time are represented.

Electron dose profile shaping by modulation of a scanning elementary beam

The use of multiple high energy electron beams has been limited in the treatment of deep seated tumors. This is principally because of the rapid increase in the physical electron beam penumbra as a result of the rise in large angle scattering with depth in the patient. This decreases the transverse dose gradient between the target volume and sensitive dose limiting structures and diminishes the ability to conform electron isodose lines to the target volume. If the beam is flat in air, then its profile will become progressively more rounded with depth, due to the increase of scatter out of the beam edges. With a scanning elementary electron beam, such as produced by the Microtron MM50, the characteristics of a broad beam profile are determined by the scan pattern. Using an appropriate scan pattern one can create, at any depth within the range of electrons, various dose profiles with the sharpness not exceeding that of the elementary beam. The objective of this work was to study methods that produce the desired electron beam profile at the depth of the target volume, and to derive the surface fluence profile required. Two approaches were explored to modulate the elementary beam distribution: "amplitude modulation" (AM) and "frequency modulation" (FM). We calculated coordinate and intensity distributions of the 25, 40, and 50 MeV elementary beam pulses at the surface that would yield a flat field at various prescribed depths. The results are in good qualitative agreement with iterative deconvolution calculations by Brahme et al. [Acta Radiol. Oncol. 19, 305-319 (1980)]. The scattering penumbra between the 50%-90% isodose lines can be reduced by up to 40% by beam modulation. The modulation should also enable the combination of multiple electron beams so as to achieve the desired conformal isodose profile as is customarily seen with photon beam planning, but with greater normal tissue sparing due to higher electron longitudinal depth--dose gradients. The results can be also used for electron accelerators that do not use a scanning elementary beam.

Elementary electron transfer processes in aqueous ionic solution

Les premieres etapes d'un transfert d'electron dans une solution de chlorure de sodium sont etudiees par spectroscopie d'absorption femtoseconde du solute ionique. L'influence du rapport moleculaire (R = [H 2 O]/[NaCl]) sur les configurations electroniques de Cl - et sur la dynamique de differents canaux de detachement d'electron est analysee dans la gamme spectrale 3.44-0.99 eV (360 - 1250 nm). Les resultats mettent en evidence l'effet de champ electrique de l'ion sodium sur un processus specifique de transfert d'electron. Ce canal met en jeu des paires electron-atome de chlore a tres courte duree de vie ({(Cl :e - ) pair :(Na + ) hyd }) et aboutit a un etat relaxe de type polaron ({e - :Na + ) hyd }).

Relaxation of excited species in He/N2 pulsed RF discharges: kinetics of metastable species

The relaxation in the afterglow of excited species produced in a pulsed parallel plate RF discharge of N2 and/or He has been investigated. Diagnostic aspects about the measurement of the electron energy distribution function by time-resolved Langmuir probe, of the decay of N2(A3 Sigma u+, V=0,4) and He(23S) metastable by LIF spectroscopy, and of N2(C3 Pi u,V'), N2+(B2 Sigma u+, V') species by time-resolved emission spectroscopy are examined. The features of the relaxation of such species in the afterglow are reviewed in the light of some elementary electron and metastable kinetics which affect the properties of the afterglow in a millisecond timescale.

RADIATION FROM A RINDLER-DIRAC ELECTRON

We evaluate the elementary quantum electrodynamics vertex involving Rindler particles and the elementary vertex involving Rindler electrons and a Minkowski photon. Also, we study the general features of the radiation emitted and the possible changes in the electron quantum numbers arising from the corresponding processes. A particularly interesting result is a spin depolarization effect arising even in the absence of external magnetic fields. Similarities to other classical and semiclassical results are briefly discussed.

Multiphoton mechanism of generation of elementary excitations in disperse SiO 2

The generation of elementary electron excitations in small particles of SiO 2 under intensive infrared excitation ( λ exc = 1064 nm, F exc = 10 5 −2 × 10 8 W/cm 2, τ p = 20 ns) was examined. The analysis of these processes was based on the investigations of spectral-luminescence properties under multiphoton excitation of a dispersion of small particles of SiO 2. It was determined that the generation mechanisms of elementary electron excitations in such samples of SiO 2 are the photoionization process under multiphoton charge modification of defect centers and the generation of relaxed excitons in non-disturbed silica.

The construction and evaluation of a low-cost isokinetic knee exerciser

An inexpensive knee exerciser which closely approximates the performance of state-of-the-art isokinetic equipment has been constructed and a preliminary evaluation has been carried out. Unlike other exercisers, the lower limb angular velocity cannot be set a priori but, on the basis of patient performance it is possible to restrict limb velocity to within upper and lower bounds. The exerciser makes use of a shock absorber and lever mechanism which allow easy calibration of the system while elementary electronics and computer interfacing allow the measurement angle, velocity and torque in real time. A significant advantage of this exerciser over some isokinetic knee exercisers currently on the market is that limited arc rotation can be enforced. This type of limb restriction is important in many rehabilitation programs.

Role of charge transfer for the vibrational-mode-specific chemical reaction of excited ammonia(1+) cation and ammonia

New reaction pathways involving (NH[sub 3] [center dot] NH[sub 3])[sup +] charge-transfer (CT) complex formation have been proposed for the vibrational-mode-specific reaction of NH[sub 3][sup +]([nu]) with NH[sub 3] using the concept of a meta-IRC (intrinsic reaction coordinate). It is known experimentally for the reaction that there are three elementary processes, electron transfer (ET), proton transfer (PT), and hydrogen abstraction (HA). The CT complex formation plays a key role in the authors' proposed reaction pathways for both ET and HA processes: in ET the reactants form the CT complex, which then dissociates to NH[sub 3][sup +] and NH[sub 3] with an electron transferred from one to the other, while in HA the CT complex does not dissociate but undergoes a rearrangement to form the (NH[sub 4] [center dot] NH[sub 2])[sup +], complex, which dissociates to NH[sub 4][sup +] and NH[sub 2]. The overall HA process has been predicted to have no energy barrier and to be exothermic by 15.8 kcal/mol at the HF/4-31G level of calculation. The authors have suggested that three characteristic transition points (TP's) exist for the reaction pathway of HA: (1) the primary TP of the CT process prerequisite for the HA to occur, (2) the geographical more » TP of the potential surface, i.e., the conventional transition state (TS) for the HA process, and (3) the secondary TP of the geometrical change for the HA process. For the ordinary reaction coordinate, the conventional TS merges the TP of CT and the geometrical TP, but in this case the character of the conventional TS splits into the three TP's. In particular, it is found that the CT process around the primary TP is most significant for the vibrational-mode specificity of the ET and HA processes. Moreover, their mechanism elucidates the non-state-selected experimental results: the reaction proceeds via PT (85%) rather than HA (15%) and ET is negligible. « less

On the energy gap for Fe-poor oxide and silicate minerals

A relationship between the energy gap (E G) and the density (ρ) over mean atomic weight (〈A〉) ratio for Fe-poor oxide and silicate minerals is derived from simple properties of their free atom-components. Theoretical considerations are based on the Lorentz electron theory of solids. The eigenfrequency ν 0 of elementary electron oscillators, in energy units h ν 0, is identified with the energy gap of a solid. The numerical relation is of the form $$(\langle U_0 \rangle ^2 - E_G^2 )\frac{{\langle A\rangle }}{\rho } = \frac{4}{3}\pi \hbar ^2 \frac{{e^2 }}{m}N = 276.79 eV^2 cm^3 /mol$$ where 〈U 0〉 is the average first ionization potential (per free atom), ħ is crossed Planck's constant, e is the electron charge, m is the electron rest mass, and N is Avogadro's number. For several geophysically interesting oxide and silicate minerals which are in general composed of four different elements (O, Si, Mg and Al), we obtain from laboratory data that the mean value of $$\left\langle {[\langle U_0 \rangle ^2 - (E_G^{lab} )^2 ]\frac{{\langle A\rangle }}{\rho }} \right\rangle \approx 248.2 \pm 20.9eV^2 cm^3 /mol.$$ .

Temperature dependence of cytochrome photooxidation and conformational dynamics of Chromatium reaction center complexes

A temperature dependence of multiheme cytochrome c oxidation induced by a laser pulse was studied in photosynthetic reaction center preparations from Chromatium minutissimum. Absorbance changes and kinetic characteristics of the reaction were measured under redox conditions where one or all of the hemes of the cytochrome subunit are chemically reduced (E h =+300 mV or E h =-20 to -60 mV respectively). In the first case photooxidation is inhibited at temperatures lower than 190-200 K with the rate constant of the photooxidation reaction being practically independent on temperature over the range of 300 to 190 K (k=2.2×10(5) s(-1)). Under reductive conditions (E h =-20 to -60 mV) lowering the temperature to 190-200 K causes the reaction to slow from k=8.3×10(5) s(-1) to 2.1×10(4) s(-1). Under further cooling down to the liquid nitrogen temperature, the reaction rate changes negligibly. The absorption amplitude decreases by 30-40% on lowering the temperature. A new physical mechanism of the observed critical effects of temperature on the rate and absorption amplitude of the multiheme cytochrome c oxidation reaction is proposed. The mechanism suggests a close interrelation between conformational mobility of the protein and elementary electron tunneling act. The effect of "freezing" conformational motion is described in terms of a local diffusion along a random rough potential.

Energy gap and density in SiO2 polymorphs

A relationship between the energy gap (E G) and density (ρ) for pure SiO2 polymorphs is derived from atomic weights and first ionization potentials of free silicon and oxygen atoms. Theoretical considerations are based on the Lorentz electron theory of solids. The eigenfrequency v0 of elementary electron oscillators, in energy units h v0, is identified with the energy gap of a solid. The numerical relation is expressed as $$E_G = \sqrt {139.24 - 13.8327\rho } $$ is in eV. For low-quartz with a density of 2.65 g/cm3 and also for stishovite with a density of 4.28 g/cm3, the energy gap E G=10.1 eV and 8.9 eV, respectively. From laboratory measurements for low-quartz E G=10.2 eV. The energy gap-density relation suggests a critical density value of ρx ≈ 10.1 g/cm3 for an SiO2 phase when the energy gap vanishes (E G=0), which is consistent with estimated densities for a high pressure silica polymorph with the fluorite structure.

Elementary Electronics

Elementary Electronics

Design principles and clinical possibilities with a new generation of radiation therapy equipment. A review.

The main steps in the development of isocentric megavoltage external beam radiation therapy machines are briefly reviewed identifying three principal types or generations of equipment to date. The new fourth generation of equipment presented here is characterized by considerably increased flexibility in dose delivery through the use of scanned elementary electron and photon beams of very high quality. Furthermore the wide energy range and the possibility of using high resolution multileaf collimation with all beam modalities makes it possible to simplify irradiation techniques and increase the accuracy in dose delivery. The main design features are described including a dual dipole magnet scanning system, a photon beam purging magnet, a helium atmosphere in the treatment head, a beam's eye view video read-out system of the collimator setting and a radiotherapeutic computed tomography facility. Some of the clinical applications of this new type of radiation therapy machine are finally reviewed, such as the ease of performing beam flattening, beam filtering and compensation, and the simplification of many treatment techniques using the wide spectrum of high quality electron and photon beams. Finally the interesting possibility of doing conformation and more general isocentric treatments with non-uniform beams using the multileaf collimator and the scanning system are demonstrated.

Redox migration mechanism of charge transport in molecularly doped polymers

Abstract A simple model of hopping transport in a molecularly doped polymer is described based on a small electric-field perturbation of diffusional (random walk) electron self-exchange reactions in the solid state. A master expression is derived which quantitatively accounts for the electrical field, temperature and concentration dependence of the hole mobility in the N,N′-diphenyl-N,N′-bis(3-methylphenyl)-[1,1′-biphenyl]-4,4′-diamine/polycarbonate system in terms of fundamental electron exchange parameters employed in modern (semi-classical) electron-transfer theory. Charge mobility which is simply related to electron hopping between neighbouring oxidized/reduced sites is assumed and shown to be normally thermally activated. The electric-field dependence of mobility is derived by modifying the zero-field Arrhenius rate expression for charge diffusion in a manner analogous to the derivation of the overpotential (electric field) dependence of charge transfer at an electrified interface. The intersite distance dependence of the mobility arises from the pre-exponential factor A′. Predictions of the model are an exponential field dependence of mobility at high fields, field-independent mobility at low fields, normal Arrhenius behaviour, decreasing activation enthalpy with increasing field, and an exponential decrease in mobility with increasing intersite distance. The free energy of activation for the elementary electron exchange reaction for this system at zero field is 0·3 eV while the inner (small molecule) and outer-sphere (medium) contributions to the overall free energy of activation are estimated, respectively, to be 0·19 and 0·13eV at 80wt%.

Crystallized and fluid intelligence in a “new” instructional situation

Twenty-four measures of crystallized intelligence (Gc) and fluid intelligence (Gf) were obtained for samples of graduates and failures of an innovative instructional setting where computer-managed mastery learning was implemented to teach elementary electricity and electronics. Seven stepwise multiple discriminant analyses and associated statistics were computed to determine which linear combinations of Gf and Gc measures could optimally separate the two groups. Corresponding classification functions derived for the discriminant analyses were applied to these measures obtained from the subjects to evaluate the effectiveness of differentiating failures and graduates. The results did not substantiate the hypothesis that Gf measures would be associated with student success in new instructional situations more so than Gc measures. Contrary to theory, the findings suggest that some unconventional educational environments are not necessarily dysfunctional for better abled students. In these situations they can just as easily exercise and exploit those skills developed and applied in more traditional instructional settings.

On the relationship between refractive index and density for SiO2 polymorphs

The Gladstone-Dale law (specific refraction) and the Drude law (molecular refraction) for silica polymorphs, at “sodium light” (λ D =0.5893 μm), are derived from simple atomic properties of SiO2 complex (atomic weight, first ionization potential). The considerations are based on the Lorentz electron theory of solids. The characteristic frequency (or eigenfrequency) v 0 of elementary electron oscillators (in energy units, hv) is identified with the band gap E G of a solid; on the other hand, this E G -gap is identified with the single ionization potential $$\tilde U$$ of non-free atoms. For $$\tilde U$$ =E G =10.2 eV (energy gap of quartz, see Nitsan and Shankland 1976b) the Gladstone-Dale law, or specific refraction, is (n−1)/ρ=0.208 cm3/g, where n and ρ are the refractive index and the density of medium, respectively. According to empirical data, the average value of the specific refraction of pure SiO2 polymorphs (except stishovite-high density phase of silica) is (〈n〉−1)/ρ=0.207±0.001 (〈n〉 denotes the mean refractive index of crystal). For stishovite the Drude law (n 2−1)/ρ=0.542 cm3/g is valid under an assumption that the first ionization potential $$\tilde U$$ =E G ≈9 eV; this result is good agreement with the empirical value (〈n〉2−1)/ρ=0.536 cm3/g.

Elementary surface excitations and electron energy loss spectroscopy

Energy loss spectroscopy of electrons reflected from solid surfaces has become a major source of information about a variety of elementary excitations of the surface. These excitations comprise plasmons of free carriers in metals and semi-conductors, interband transitions, electronic excitations of adsorbed molecules and, with high resolution spectroscopy, vibrations of adsorbates and the substrate. Our understanding of surface chemistry is greatly improved by the spectroscopy of adsorbate vibrations since decomposition reactions of adsorbed molecules on surfaces are easily analysed by the characteristic eigenmodes of the products. In many cases new and unexpected surface species have been identified. One of the advantages of electron energy loss spectroscopy as opposed to other techniques is that different scattering mechanisms may be employed which have different selection rules with respect to the symmetry elements of adsorbate complexes. Recently even surface phonon spectroscopy has become possible, and the dispersion of Rayleigh waves has been measured throughout the Brillouin zone.

USTAAD — An interactive pedagogical aid for elementary electronic circuit analysis

Describes USTAAD, a Computer Aided Learning (CAL) program which provides self-paced test and drill facilities in elementary electronics circuit analysis. Circuits, either synthesized or user-specified, are displayed on the user's terminal. The user can be quizzed on electrical properties of these circuits and/or he can interactively analyze them. A sophisticated calculator frees the user from paper-and-pencil calculations, and an adequate editing facility allows interactive circuit design. The integration of USTAAD's varied capabilities and the environmental features of USTAAD are emphasized.

Elementary Electronic Excitations in Pure Sodium Silicate Glasses

AbstractElectronic structure in high‐purity sodium silicate glasses is studied. The spectral dependence of the relative quantum yield of the external and internal photoemission, the luminescence excitation spectra, the luminescence decay, and the polarization degree of the luminescence are measured. The luminescence band at 3.4 eV is created by the intrinsic anisotropic luminescence centre labelled L, whose absorption causes the fundamental absorption tail of high‐purity silicate glasses, where the localized elementary excitations are created by photons. The phonon‐assistent or tunneling delocalization processes produce colour centres. An electron release from the L‐centre leads to the creation of the H‐centre. An electron capture of the L‐centre results in the E‐centre. A model of the structure Na+ ‐ O−‐ Si = is proposed for the L‐centre. Hence the structure for the E‐centre model will be Na0. O−  Si =, but for the H‐centre it will be Na+ O  Si =. The pair of E and H‐centres can probably recombine in a tunneling process.

The idea of the neutrino

During the 1920's physicists came to accept the view that matter is built of only two kinds of elementary particles, electrons and protons, which they often called “negative and positive electrons.” A neutral atom of mass number A and atomic number Z was supposed to contain A protons, all in the nucleus, and A negative electrons, A–Z in the nucleus and the rest making up the external electron shells of the atom. Their belief that both protons and negative electrons were to be found in the nucleus arose from the observations that protons could be knocked out of light elements by alpha-particle bombardment, while electrons emerged spontaneously (mostly from very heavy nuclei) in radioactive beta decay. Any other elementary constituent of the atom would have been considered superfluous, and to imagine that another might exist was abhorrent to the prevailing natural philosophy.