Frequency Shifts Of Spectral Lines Research Articles

Frequency Shifts of Spectral Lines Generated by Young's Pinhole Wave Scattering Upon a Quasi-Homogeneous Medium

Frequency shifts of light scattered from either a deterministic or random medium have shown great importance in remote sensing imaging applications, however, such scattering system which combines random scatterer with obstacles has not been specifically discussed so far. To solve this problem, we derive analytical expressions for showing the phenomenon that the Young's pinhole wave scattered from a quasi-homogeneous (QH) medium exhibits the red shift of spectral lines, while the first-order Born approximation is applied to treat the weak scattering between the diffractive wave and the medium. The shifted amount of spectrum is strongly dependent of the scattering angle, correlation length of the medium, and Young's pinhole parameter. Furthermore, we also observe that the red shift of the scattered spectrum converts to the blue shift when the correlation length reaches a certain magnitude. Through numerical simulations, analyses are performed on revealing the effects of Young's pinhole parameter and medium's correlation on the spectral shift and spectral switch of the scattered spectrum.

Spectral changes of stochastic beams scattered on a deterministic medium

It is well known that scattering of a polychromatic plane wave by a random medium, i.e., by a medium whose refractive index varies randomly with position, may produce frequency shifts of spectral lines. It has been a common perception that a random medium is required for generation of such spectral shifts by scattering. In this Letter we show that such a phenomenon occurs even when the refractive index of the medium is a deterministic function of position. We also show that this phenomenon may be used to obtain information about the structure of a deterministic medium.

Frequency shifts of spectral lines induced by scattering from a rotational anisotropic particle

We investigate the scattering of a polychromatic plane light wave incident upon an anisotropic particle. It is different from light wave scattered by an isotropic particle that the frequency shifts of spectral lines will be induced by the rotation of the anisotropic particle. The analytical expression for the spectrum of the scattered field is derived and numerical examples are also illustrated. We suggest an application that the angular speed of rotation of the anisotropic scatterer can be scaled by measurement of the spectrum of the scattered field.

Broadening of spectral lines due to dynamic multiple scattering and the Tully-Fisher relation

The frequency shift of spectral lines is most often explained by the Doppler effect in terms of relative motion, whereas the Doppler broadening of a particular line mainly depends on the absolute temperature. The Wolf effect, on the other hand, deals with the correlation-induced spectral change and explains both the broadening and shift of the spectral lines. In this framework a relation between the width of the spectral line is related to the redshift z for the line and hence with the distance. For smaller values of z a relation similar to the Tully-Fisher relation can be obtained and for larger values of z a more general relation can be constructed. The derivation of this kind of relation based on dynamic multiple-scattering theory may play a significant role in explaining the overall spectra of quasistellar objects. We emphasize that this mechanism is not applicable for nearby galaxies, $z<~1$.

Effect of multiple scattering on broadening and the frequency shift of spectral lines

The effect of multiple scattering on the broadening and the shift of the spectral lines of light propagating in a medium is investigated within Wolf's framework. The condition for no blueshift is derived. It is shown that under the same hypothesis the property $\ensuremath{\Delta}{\ensuremath{\omega}}_{N+1}\ensuremath{\gg}{\ensuremath{\delta}}_{N}$ is satisfied. Moreover, the no blueshift condition has been found to be closely related to the no blurring condition. These results might be of relevance in the astronomical domain.

Frequency Shift of Spectral Lines Generated by Multiple Dynamic Scattering

The frequency shift of spectral lines generatedby single dynamic scattering is known from Wolf'spioneering work. The multiple scattering effect isdiscussed and for the case of redshift two main results are shown: (1) the multiple scattering effectcauses a larger shift than does single scattering, and(2) m scatterings with scattering angle θ/m eachproduce a larger shift than that done by n scatterings with scattering angle θ/n each if m >n. These results might be of particular interest inconnection with the observed spectra ofquasars.

A class of scattering media which generate Doppler-like frequency shifts of spectral lines

It has been known for some time that under certain circumstances scattering from fluctuating media can generate shifts of spectral lines which are indistinguishable from those due to the Doppler effect, even though the source of the radiation, the scatterer and the observer are at rest with respect to each other. In this Letter a class of correlation functions of scattering media is introduced, each of which can generate such Doppler-like shifts. Red shifts as well as blue shifts can be produced by this mechanism, depending on the scattering geometry. We illustrate the results by an example involving diffusion in the presence of a random source.

Shifts of spectral lines caused by scattering from fluctuating random media

view Abstract Citations (40) References (25) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Shifts of Spectral Lines Caused by Scattering from Fluctuating Random Media James, Daniel F. V. ; Savedoff, Malcolm P. ; Wolf, Emil Abstract A model scatterer is introduced, whose dielectric response function is a random function of space and time and which produces frequency shifts of spectral lines that imitate the Doppler effect in its main features. The possible relevance of this effect to the origin of discrepancies observed in some quasar spectra is discussed. Publication: The Astrophysical Journal Pub Date: August 1990 DOI: 10.1086/169034 Bibcode: 1990ApJ...359...67J Keywords: Dielectric Properties; Doppler Effect; Light Scattering; Line Spectra; Quasars; Red Shift; Active Galactic Nuclei; Random Processes; Rayleigh Scattering; Astrophysics; GALAXIES: REDSHIFTS; QUASARS; RADIATION MECHANISMS full text sources ADS | data products SIMBAD (3)

Frequency shifts of spectral lines produced by scattering from spatially random media:errata

Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text E. Wolf, J. T. Foley, and F. Gori, "Frequency shifts of spectral lines produced by scattering from spatially random media:errata," J. Opt. Soc. Am. A 7, 173-173 (1990) Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article

Correlation-induced Doppler-type frequency shifts of spectral lines.

The question is examined whether there may be scattering media which could generate spectral frequency shifts in radiation from sources that are at rest relative to the observer and yet would imitate Doppler shifts. Scattering kernels of media whose physical properties fluctuate randomly in both space and time are presented which achieve this to a good approximation. The frequency shifts produced in this manner are not necessarily small. The results might be of particular interest in connection with the long-standing controversy about the origin of some of the large redshifts observed in the spectra of certain quasars.

Frequency shifts of spectral lines produced by scattering from spatially random media

Scattering of polychromatic light by a medium whose dielectric susceptibility is a random function of position is considered within the accuracy of the first Born approximation. It is shown, in particular, that if the two-point spatial correlation function of the dielectric susceptibility has Gaussian form and the spectrum of the incident light has a Gaussian profile, the spectrum of the scattered light may be shifted toward the shorter or the longer wavelengths, depending on the angle of scattering. The results are analogous to those derived recently in connection with radiation from partially coherent sources [ Nature (London)326, 363 ( 1987)].

Frequency shifts of spectral lines generated by scattering from space-time fluctuations.

The scattering of a class of partially coherent electromagnetic fields by a model medium whose dielectric susceptibility fluctuates in space and in time is considered within the accuracy of the first-order Born approximation. It is shown that if the incident field is a linearly polarized, polychromatic plane wave whose spectrum is a line of Gaussian profile, the spectrum of the scattered light is, in some cases, approximately Gaussian and is shifted towards the shorter or the longer wavelengths, depending upon the angle of scattering.

Observation of frequency shifts of spectral lines due to source correlations.

Realisation d'une experience acoustique avec deux petites sources partiellement correlees et demonstration du deplacement en frequence des raies spectrales