Articles you may be interested inQuantitative measurement of phase variation amplitude of ultrasonic diffraction grating based on diffraction spectral analysis Rev. Sci. Instrum. 85, 093112 (2014);A twocolor laserinduced grating technique for gasphase excitedstate spectroscopy A detailed analysis of diffraction from laser-induced gratings is presented. The changes which occur in both the real and imaginary parts of the index of refraction are accounted for when excited states are created. These lead to phase and amplitude grating contributions, respectively, to the diffraction from a laser-induced excited state grating. Experimental confirmation of the predicted wavelength dependence of these contributions is presented. Diffraction from laser-induced excited state gratings, ultrasonic wave gratings, and mixed excited state and acoustic gratings is analyzed with the phase and amplitude contributions to each accounted for. The results permit the interpretation of mixed grating data and predict conditions under which densitY-dependent absorption spectral shifts and excited state-phonon interactions can be measured.1144

International audienceThe temperature-induced structural modifications of poly(N-isopropylacrylamide) hydrogel (pNIPA) were investigated by small-angle X-ray scattering (SAXS) over a broad range of q values (3.5 x 10(-2)-12 nm(-1)) at temperatures ranging between 18 and 37 degrees C. The sample Studied was claborated by cryopolymerization yielding a macroporous gel (cryogel). The pNIPA gel forms the walls (the thickness at 23 degrees C is about 12 mu m). The SAXS curves display an isoscattering (or isosbestic) point located at q(iso) = 3.633 nm(-1) and disappearingabovc 30 degrees C. This feature has never been reported up to now. The SAXS curves obtained at each temperature are well fitted by a sum of four equations describing respectively the scattering resulting from the gel surface (power law), from the solidlike (Guinier equation) and liquidlike (Ornstein - Zernike equation) heterogeneities, and from the chain-chain correlation yielding a broad peak (pseudo-Voigt equation) in the high-q domain. The temperature dependence of the parameters obtained from the fit is analyzed and discussed

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