Doppler energy

In real gases and liquids, however, atoms are never at rest. If y-emission takes place while the nucleus (or atom) is moving at velocity Un in the direction of the y-ray propagation, the y-photon of energy Ey is modulated by the Doppler energy Ep, [3] ... 

The dependence of Mossbauer parameters on geometric arrangements is mainly due to the cosine smearing of the velocity u. Since the Doppler energy shift AEy is given by... 

Hoyer PF, Schmid R, Wiinsch L, Vester U (1999) Colour Doppler Energy - a new technique to study tissue perfusion in renal transplants. Pediatr Nephrol 13 559-563... 

Hohenfellner K, Huntley TE, Brezinska R et al (1999) ACE I/D gene polymorphism predicts renal damage in congenital uropathies. Pediatr Nephrol 13 514-518 Hoyer PF, Schmid R, Wiinsch L et al (1999) Color Doppler energy-anewtechnique to study tissue perfusion in renal transplants. Pediatr Nephrol 13 559-563 Hunley TE, Kon V (1999) IgA nephropathy. Curr Opin Pediatr 11 152-157... 

In fact, there are some approaches to employ to shift the emission line so as to increase the probability of its overlapping with absorption lines. One approach is the Doppler effect when the source (nucleus) is moving at a velocity in the direction of the ray propagation, the gamma quantum of energy, Ey, receives a Doppler energy Ed,... 

There are several types of source, e.g. Co, Sm, Gd, and " " Sn, which are applicable for varied samples, respectively. When probing Fe samples, the excited radioactive source Co/Rh ( Co in a rhodium matrix) decays via electron capture with emitted gamma rays at 122 and 14.4 keV with additionally imparted Doppler energy since the source moves relative to the absorber. The source under the control of a velocity transducer can move back and forth with constant velocity, sinusoidally, in a symmetric sawtooth, or any other complicated way therefore, the Doppler energy as well as the energy of gamma quanta can be modified in a controllable marmer. 

Figure B2.5.12 shows the energy-level scheme of the fine structure and hyperfme structure levels of iodine. The corresponding absorption spectrum shows six sharp hyperfme structure transitions. The experimental resolution is sufficient to detennine the Doppler line shape associated with the velocity distribution of the I atoms produced in the reaction. In this way, one can detennine either the temperature in an oven—as shown in Figure B2.5.12 —or the primary translational energy distribution of I atoms produced in photolysis, equation B2.5.35.

Figure C3.3.6. Doppler-line profiles for molecules scattered into the CO COO O J= 72) state by collisions with hot methylpyrazine molecules as depicted by the equations above each half of the figure. The energy of methylpyrazine...

Figure C3.3.7. In the upper half of the figure are shown typical measured Doppler profiles for molecules scattered into the (OO O J= 72) or (OO l J = 17) states of CO2 by collisions with hot pyrazine having an energy of 40 640 cm In the lower half of the figure is shown a typical intennolecular potential identifying the hard and soft collision regimes and the kind of energy transfer they effect.

In practice the laser can operate only when n, in Equation (9.2), takes values such that the corresponding resonant frequency v lies within the line width of the transition between the two energy levels involved. If the active medium is a gas this line width may be the Doppler line width (see Section 2.3.2). Figure 9.3 shows a case where there are twelve axial modes within the Doppler profile. The number of modes in the actual laser beam depends on how much radiation is allowed to leak out of the cavity. In the example in Figure 9.3 the output level has been adjusted so that the so-called threshold condition allows six axial modes in the beam. The gain, or the degree of amplification, achieved in the laser is a measure of the intensity. 

Multiphoton Absorption and Ionization. High laser powers can induce the simultaneous absorption of two or more photons that together provide the energy necessary to excite a transition this transition may be one that is forbidden as a single-photon process (8,297). Such absorption can be made Doppler-free by propagating two laser beams of frequency V in opposite directions, so the Doppler shifts cancel and a two-photon transition occurs at 2v for any absorber velocity. The signal is strong because aU absorbers contribute, and peak ampHtudes are enhanced by, which may... 

Chapter 3 is devoted to pressure transformation of the unresolved isotropic Raman scattering spectrum which consists of a single Q-branch much narrower than other branches (shaded in Fig. 0.2(a)). Therefore rotational collapse of the Q-branch is accomplished much earlier than that of the IR spectrum as a whole (e.g. in the gas phase). Attention is concentrated on the isotropic Q-branch of N2, which is significantly narrowed before the broadening produced by weak vibrational dephasing becomes dominant. It is remarkable that isotropic Q-branch collapse is indifferent to orientational relaxation. It is affected solely by rotational energy relaxation. This is an exceptional case of pure frequency modulation similar to the Dicke effect in atomic spectroscopy [13]. The only difference is that the frequency in the Q-branch is quadratic in J whereas in the Doppler contour it is linear in translational velocity v. Consequently the rotational frequency modulation is not Gaussian but is still Markovian and therefore subject to the impact theory. The Keilson-... 

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