Spectral stability

In practical application, Raman sensors exclusively use frequency-stabilised laser sources to compensate for the low intensity of the Raman radiation. For Raman sensors, prevalently compact high-intensity external cavity laser diodes are used, operated in CW (continuous wave) mode. These diode lasers combine high intensity with the spectral stability required for Raman applications and are commercially available at various wavelengths. 

A.P. Kulkarni and S.A. Jenekhe, Blue light-emitting diodes with good spectral stability based on blends of poly(9,9-dioctyfluorene) interplay between morphology, photophysics, and device performance, Macromolecules, 36 5285-5296, 2003. 

Thus, all of the harmonics i= TkX are stable under one and the same condition a > a0. We are going to show that the stability of scheme (16a) in every harmonic known as the spectral stability implies that in the grid L2-norm with respect to the initial data y(x, 0) = 0(x). where m0(x) is a grid function defined for 0 < x < 1 and vanishing at the points x — 0 and x = l. With this aim, the general solution of problem (16a) is sought as the sum of particular solutions having the form (22) ... 

Copolymers 10 derived from 3,6-dibenzosilole and 2,7-fluorene are blue electroluminescent SCPs.27 When the copolymers are used as the emissive layer in EL devices, highly efficient pure blue emissions with CIE coordinates of (x = 0.16, y = 0.07), a 7EL of 3.34%, and a luminance efficiency of 2.02 cd/A at 326 cd/m2 are achieved from the copolymer with 90% fluorene content. The blue color matches the NTSC blue standard (x = 0.14, y = 0.08) quite well. The EL spectral stability of the devices is quite good, even under operation at elevated temperatures. Copolymer 9 derived from 3,6- and 2,7-dibenzosiloles also exhibits high performance with a jyEE of 1.95%, a luminous efficiency of 1.69 cd/A, and a maximal brightness of 6000 cd/m2, with the CIE coordinates of (x = 0.162, y = 0.084).26... 

The constitutive equations are the Oldroyd-B model and a modified Oldroyd-B model in which the viscosity depends on the rate of strain. In [79], Laure et al. study the spectral stability of the plane Poiseuille flow of two viscoelastic fluids obeying an Oldroyd-B law in two configurations the first one is the two layer Poiseuille flow in the second case the same fluid occupies the symmetric upper and lower layers, surrounding the central fluid. (See Figure 9.)... 

For the numerical study of the whole spectrum (for g R fixed), [79] uses a spectral tau-Chebychev discretization in y and the Arnold method (see [88]) to solve the generalized eigenvalue problem (see [89]). This numerical method is based on the orthonormalization of the Krylov space of the iterates of the inverse of the matrix A B. This method has been used more recently in [90]. It has been proven efficient in the stiff problems arising in the study of spectral stability of viscoelastic fluids. 

Let us finally quote some more references where the flow is neither the Poiseuille, nor the Couette one. In [94], Oztekin and Brown study the spectral stability of the flow of... 

The important problem of stability of viscoelastic flows is far more involved than for Newtonian flows, and many problems still remain open. However, it is clearly established that the difficulty lies in the relationship between various mathematical notions of stability. Some results have been obtained in this direction for restricted classes of flows and/or of models. Moreover several important studies of spectral stability have been performed. 

Kammeyer A, Westerhof W, Bolhuis PA, Ris AJ, Hische EA. The spectral stability of several sunscreening agents on stratum comeum sheets. Int J Cosmet Sci 1987 9 125-136. 

The better spectral stability of sp-PF-2 as compared with sp-PF-1 maybe attributed to a less effective exciton migration to the fluorenone defects. As shown in the inserts of Figure 5.12b and Figure 5.12c the amount of defects created in the two spiro-type materials is similar, if not even more defects are created in sp-PF-2. Nevertheless, sp-PF-1 shows an almost twofold relative increase in keto emission after... 

Figure 6. Because of the inherent spectral stability of fluorescent...

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