Stokes doublet

The next two temis (Lorentzians) arise from the mechanical part of the density fluctuations, the pressure fluctuations at constant entropy. These are the adiabatic sound modes (l/y)exp[-FA t ]cos[co(A) t ] with (D(k) = ck, and lead to the two spectral lines (Lorentzians) which are shifted in frequency by -ck (Stokes line) and +ck (anti-Stokes line). These are known as the Brillouin-Mandehtarn, doublet. The half-width at... 

Physically, the Brillouin spectrum arises from the inelastic interaction between a photon and the hydrodynamics modes of the fluid. The doublets can be regarded as the Stokes and anti-Stokes translational Raman spectrum of the liquid. These lines arise due to the inelastic collision between the photon and the fluid, in which the photon gains or loses energy to the phonons (the propagating sound modes in the fluid) and thus suffer a frequency shift. The width of the band gives the lifetime ( 2r)-1 of a classical phonon of wavenumber q. The Rayleigh band, on the other hand, represents the... 

Fluorescence Decay. The fluorescence is mainly from the v = 32 vibrational level of state 5 to various v" levels of the ground state, each consisting of a rotational doublet as discussed in Exp. 39. This emission will be to the red (long wavelength or Stokes) side of the 532-nm excitation source thus an orange or red filter is used to block green and pass red light. It is not necessary to resolve the emission into individual transitions since the decay rate of each is assumed to have the same dependence on the upper B state concentration, I2. 

Hu M, Wang C-Y, Li Y, Chai L, Kondrat ev YN, Sibflia C, Zheltikov AM (2(X)4) An anti-Stokes-shifted doublet of guided modes in a photonic-crystal fiber selectively generated and controlled with orthogonal polarizations of the pump field. Appl Phys B Laser Optic 79 805-809... 

From the breadth of the primary peak obtained in the line-start characterization study, it can be seen that the measured range of Stokes diameters in the primary fineparticle population of the latex is 2.42—2.92 pm. The two subsidiary peaks are obviously doublets. The centrifuge has been able to resolve the orientation with which the doublets are falling with respect to the radial direction of the centrifugal force field in the centrifuge. The two subsidiary peaks in Figure 4.12 occur at 0.76T and 0.56T,... 

The simple theory given above shows the origin of the Brillouin doublet which is the Stokes and anti-Stokes components of the scattered light each shifted from the frequency of the incident light by an amount given by Eq. (81). However what is observed experimentally is a triplet -three distinct bands. One of these is centered about the laser line itself and is called the Rayliegh line while the others constitute the Brillouin doublet. A schematic spectrum of the Rayliegh line and the Brillouin doublet is shown in Fig. 7. 

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