Electronic doppler effect

High-resolution spectroscopy used to observe hyperfme structure in the spectra of atoms or rotational stnicture in electronic spectra of gaseous molecules connnonly must contend with the widths of the spectral lines and how that compares with the separations between lines. Tln-ee contributions to the linewidth will be mentioned here tlie natural line width due to tlie finite lifetime of the excited state, collisional broadening of lines, and the Doppler effect. 

Mossbauer spectra are usually recorded in transmission geometry, whereby the sample, representing the absorber, contains the stable Mossbauer isotope, i.e., it is not radioactive. A scheme of a typical spectrometer setup is depicted in Fig. 3.1. The radioactive Mossbauer source is attached to the electro-mechanical velocity transducer, or Mossbauer drive, which is moved in a controlled manner for the modulation of the emitted y-radiation by the Doppler effect. The Mossbauer drive is powered by the electronic drive control unit according to a reference voltage (Fr), provided by the digital function generator. Most Mossbauer spectrometers are operated in constant-acceleration mode, in which the drive velocity is linearly swept up and down, either in a saw-tooth or in a triangular mode. In either case. 

Experimental details for the cross-section measurements were presented in the literature. Briefly, after the irradiation by electron beam pulse for a few nanoseconds, the time-dependent absorption for the atomic line transition Rg Rg -i-/zv was measured to observe the time-dependent population of the excited rare gas atoms Rg. The population of excited Rg was determined using an absorption law for the atomic lines, where the broadening of the absorption profile due to the thermal Doppler effect and due to the attractive interatomic potentials was reasonably taken into consideration. The time-dependent optical emission from energy transfer products, such as ... 

Absorption of electromagnetic radiation by monatomic gases leads either to production of atoms in excited states or, if the wavelength is short enough, to ionization. Absorption lines have widths which depend on the following factors1 (a) the temperature, i.e. there will be a Doppler effect which will broaden the line if the absorbing atoms are in motion (b) an intrinsic factor dependent on the nature of the electronic state and on the extent of perturbations by other states ... 

The thermal motion of the atoms in the source volume leads to a broadening of the observed line, because the thermal velocity vth of the electron-emitting atom is added to the electron velocity v0. For an estimation of the resulting disturbance by this kinematical effect it is sufficient to select for the thermal velocity the two directions at which the Doppler effect becomes extreme, i.e.,... 

The first part of the energy Eq(x, p) is the kinetic energy Kin(p) = p2 / 2 M. For the matter-field interaction, this energy produces the well-known Doppler effect of inhomogeneous broadening of optical transitions. The second part is the interaction with electrodes, i.e. the Lennard-Jones potential near the equilibrium point xq = 0 taken in the harmonic approximation as Upot(x) = M O2 r 2/2. The third part is the electrostatic interaction of the dot electron in... 

For radiofrequency measurements of the fine structure of hydrogen, on the other hand, the Doppler effect is completely tmimportant, since it is proportional to the frequency which is actually measured. The fine structure intervals are given by frequency differences in optical spectroscopy in radiofrequency spectroscopy they are measured directly. The greater precision of radiofrequency measurements would compel careful investigation of the conditions in a gas discharge if this method were chosen for the excitation of the atoms. In fact, in the radio-frequency experiments which have so far been performed on hydrogen and ionized helium, the method of excitation by electron bombardment has been used. 

K. Upon increasing the temperature the isomer shift decreases, consistent with expectations based on the second-order Doppler effect. Electron density maps of the complex support the E2g ground state with an electronic configuration of (d y) (d. z.d3iz) (dz2) Another... 

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