Anisotropic ultrafast dissociation probed by the Doppler effect in resonant photoemission from CF4

The resonant Auger spectrum from the decay of F 1s-excited CF4 is measured. Several lines exhibit a nondispersive kinetic energy as the exciting photon energy is tuned through the resonance region. The F 1s(-1) atomiclike Auger line is split into two components due to the emission of Auger electrons by a fragment in motion, when electron emission is observed along the polarization vector of the light. This Doppler splitting is direct evidence that the core excitation leads to T(d)-->C(3v) symmetry lowering, by elongation of a specific C-F bond preferentially aligned along the polarization vector of the incident photon.     

On the anisotropy of electron backscattering and of the sticking coefficient of gases on single crystal surfaces

The influence of the anisotropy of backscattering of electrons with energies above the core hole ionization energy of selected Auger processes on the anisotropy of the Auger electron emission is studied using a cylindrical W single crystal. After the determination of the anisotropy of the elastic backscattering its contribution to the anisotropy of Auger electron emission from adsorption layers is obtained by postulating that all other anisotropy causes are negligible. When applied to an adsorbate with orientation-independent coverage such as Fe this leads to an orientation-dependent backscattering correction term which may be applied to adsorbates with orientation-dependent sticking coefficients such as O₂. In this manner Auger signals may be converted into true relative coverages (corrected for backscattering anisotropy). In the case of oxygen adsorption this correction is significant and leads to an orientation-independent initial sticking coefficient (of 1) over most of the 〈110〉 zone except in the neighbourhood of the {110} planes where it reaches its minimum value of 0.28.     

The operation of the relativistic Doppler effect

It is shown that the mode of operation of the relativistic Doppler effect and hence also its general formula can be deduced directly from the assumption of a cosmological fundamental reference frame, whose existence is now strongly supported by astronomical observation. Such a frame implies the existence of (relativistic) anisotropy effects on bodies and observers moving relative to it. The Doppler effect consequence is an interesting example of the emergence of relativistic effects from a simple intelligible assumption about light propagation, and shows how this assumption can provide a richer and clearer interpretation of special relativity than does the conventional formal approach.     

Mie-Rayleigh Doppler Wind Lidar with Two Double-edge Interferometers

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Angular distribution of the auger emission from aluminum and nickel surfaces

The angular distribution of the Auger emission from Ni(100), Ni(100)c(2 × 2)-S, Al(001) and Al(110) has been studied by recording azimuthal and polar profiles for the nickel and sulfur MVV Auger peaks and for the aluminum LVV Auger peak. The character of the anisotropy is very different for the aluminum and nickel surfaces: the profiles are rather smooth for aluminum and present numerous sharp structures for nickel. Moreover when the sulfur overlayer is present, the nickel Auger peak anisotropy is strongly perturbed and the emission anisotropy of the sulfur Auger peak is found very important.     

The Doppler shift and anisotropy of quasimolecular X-rays emitted in Nb+Nb collisions at 67 MeV

The quasimolecularKX-ray spectrum obtained by bombarding Nb with 67 MeV Nb ions has been found to undergo a Doppler shift with an effective Doppler velocity equal to the mean center-of-mass velocity of the intermediate Nb+Nb molecule, corresponding to the projectile velocity. By applying Doppler shift corrections the intrinsic anisotropy of the quasimolecularKX-radiation is found.     

Doppler spectroscopy on relativistic particle beams in the light of a test theory of special relativity

Modern experimental techniques based on collinear laser spectroscopy have led to greatly improved versions of the classical Ives-Stilwell experiment. The new experiments employ collinear laser beams and measure the Doppler shift as it is seen in the rest frame of a relativistic particle beam. This note analyzes these experiments in the framework of a test theory of special relativity due to Mansouri and Sexl. It is found that the experiments can test the coefficient functiona(υ² (responsible for time dilation), but are insensitive tob,d and?. While the Mansouri-Sexl theory in principle allows for an anisotropy of the velocity of light with respect to a moving reference frame, anisotropy effects cancel out in Ives-Stilwell type experiments. These experiments by themselves are not sufficient for a direct observation of such an anisotropy.     

Design of new seismometer based on laser Doppler effect

In order to improve the resolution of seismic acquisition, a new seismic acquisition system based on tangential laser Doppler effect with an optimized differential optical configuration is proposed. The relative movement of the inertia object and the immobile frame is measured by laser Doppler effect, which can avoid the electromagnetic and thermometric interference, and the adoption of frequency-modulated (FM)transmission can improve the ability of anti-jamming. The frequency bandwidth is properly determined by analyzing the frequency of the Doppler signal. The velocity, displacement, acceleration, and frequency to be measured can be real-time acquired by frequency/velocity (F/V) converting the FM Doppler signal.A 100-dB dynamic range and the linear frequency range of 1.0 to 1000 Hz are realized.     

Doppler angle and flow velocity mapping by combined Doppler shift and Doppler bandwidth measurements in optical Doppler tomography

Accurate estimation of flow velocity requires measurement of Doppler angle, which is not available in general clinical applications. We describe a novel method of direct Doppler angle and flow velocity mapping that uses a conventional single-beam optical Doppler tomography system. The Doppler angle is estimated by combination of Doppler shift and Doppler bandwidth measurements, and flow velocity is calculated from the Doppler shift and the estimated Doppler angle. In vivo study of lip microvascularization demonstrates that this method is capable of providing both flow speed and flow direction information.     

Angular resolved Auger emission from clean and sulfur covered Ni(110) surface

The angular dependence of the nickel M₂₃VV and of the sulfur L₂₃VV Auger transitions are studied in detail, on clean and sulfur covered Ni(110) surfaces. New experimental data are presented for the anisotropy of both transitions as a function of polar and azimuthai angles of emission. Our model, which incorporates at the same time the multiple scattering effects in the final state wave function and the intrinsic anisotropy of the Auger emitter, is found to give a satisfactory account of the observed auger anisotropy. We find a large sensitivity to the position of the sulfur adsorbed atoms. The best agreement is obtained for the hollow site. slightly less than 0.9 Å above the top nickel layer. This conclusion is consistent with previous LEED and MEIS studies, but does not agree with the long bridge site obtained from quantum chemistry calculations. Moreover the sulfur emitter on this particular Ni(110) face appears to have an intrinsic anisotropy.     

Spin polarization and angular distribution of Auger electrons formed as a result of decay of the 3<Emphasis Type="Italic">d</Emphasis><Superscript>−1</Superscript>5<Emphasis Type="Italic">p</Emphasis> state in the Kr atom

The results of numerical calculations of the energies of Auger transitions, as well as the angular distribution (α₂) and spin polarization (β₂) anisotropy parameters, are presented for transitions in a photoexcited Kr* atom with two open shells. Matrix elements are calculated by the multiconfigurational Fock-Dirac relativistic method using an intermediate type of coupling. The wavefunctions of the initial and final states of the Auger transition are calculated with allowance for relaxation effects. The one-electron wavefunction of the continuous spectrum for an Auger electron is obtained using the single-configuration Fock-Dirac method. The results are compared with experiment and a new experiment is proposed for identifying the Auger state not only from the energy, but also from the total angular momentum of the Auger state.     

Circularly polarized x rays: another probe of ultrafast molecular decay dynamics

Dissociative nuclear motion in core-excited molecular states leads to a splitting of the fragment Auger lines: the Auger-Doppler effect. We present here for the first time experimental evidence for an Auger-Doppler effect following F1s → a(1g)* inner-shell excitation by circularly polarized x rays in SF(6). In spite of a uniform distribution of the dissociating S-F bonds near the polarization plane of the light, the intersection between the subpopulation of molecules selected by the core excitation with the cone of dissociation induces a strong anisotropy in the distribution of the S-F bonds that contributes to the scattering profile measured in the polarization plane.     

Acoustic Doppler shifts in medicine

This is a brief discourse on the history of the uses of acoustic Doppler frequency shifts in modern medicine. The Doppler effect and the Doppler equation are discussed. The technological developments over the last half century are covered, as well as their applications in diagnostic medical sonography. A limited discussion of the pathologies that may be diagnosed using the Doppler effect is also presented.     

Experimental study of the Doppler shift generated by a vibrating scatterer

We report an experimental study of the backscattering of a sound wave of frequency f by a surface vibrating harmonically at frequency F (F < f) and amplitude A in the regime where the Doppler effect overcomes bulk nonlinear effects. When the duration to of the analyzed time series of the scattered wave is small compared to the vibration period, the power spectrum of the backscattered wave is proportional to the probability density function of the scatterer velocity, which presents two peaks shifted from f by roughly 2fAomega/c (omega = 2piF). On the contrary, when t0 > F(-1), sidebands at frequencies f +/- nF (n integer) appear in the power spectrum, which are due to the phase modulation of the backscattered wave induced by its reflection on a moving boundary. We use the backscattered power spectrum to validate the phase modulation theory of the Doppler effect in the latter case for 2kA < 1 and 2kA approximately > 1 (k = 2pif/c, where c is the wave velocity) and we test the validity of an acoustic nonintrusive estimator of A as a function of power spectrum bandwidth and of A itself.     

多普勒展宽和多普勒频移在光谱分析中的应用

分析了多普勒展宽和多普勒频移区别，讨论了高斯拟合和弦积分线形分布的差异。利用多道光学分析仪（OSMA）测量HT-6M托卡马克限制器前Hα线形分布，通过高斯拟合由多普勒展宽和多普勒频移分别得出等离子温度和粒子入射速度。     

Mie-Rayleigh Doppler Wind Lidar with Two Double-edge Interferometers

The Mie-Rayleigh direct detection Doppler lidar (DDDL) with two double-edge etalons is presented. Fabry-Perot (F-P) etalon is used as the spectral analyzer for Doppler measurement formthe aerosol and molecule backscattered signals. The aerosol and molecular backscattering signals are separated by a polarization isolator with less signal decrement, so this system has about same accuracy as individual Rayleigh Doppler lidar or Mie Doppler lidar system. The simulation on a proposed ground-based DDDL at 532 nm shows that the velocity error is less than 2 m/s below 8 km for a 100 m vertical resolution by Mie channel and 2m/s up to 20 km by Rayleigh channel, respectively.     

Emitter velocity and anisotropy for quasi-molecular radiation in I-Au collisions

The velocity of the quasimolecular x-ray emitter is found via Doppler shift measurements. It is in agreement with the center of mass velocity. Applying Doppler shift corrections the intrinsic anisotropy of the quasi-molecularM radiation is determined as a function of x-ray energy for 6 to 45 MeV I bombardment on thin Au targets. Position and amplitude of the maximum anisotropy in the x-ray spectrum depend on impact energy.     

多卜勒计程仪

本文简要回顾多卜勒计程仪的发展和用途，分析了多卜勒计仪为导航设备的优点，工作原理，主要性能及组成部件，最后介绍了多卜勒计程仪在我国的设计情况。     

Argon L-shell Auger spectra produced in Ar+ -Ar collisions

Argon L-shell Auger spectra were measured by 100 to 550 keV Ar⁺ impact on Ar. Observed line structure in the spectra are interpreted both by multiple outer-shell ionization and Doppler effects.