We successfully acquire the in vivo Raman spectrum of melanin from human skin using a rapid near-infrared (NIR) Raman spectrometer. The Raman signals of in vivo cutaneous melanin are similar to those observed from natural and synthetic eumelanins. The melanin Raman spectrum is dominated by two intense and broad peaks at about 1580 and 1380 cm(-1), which can be interpreted as originating from the in-plane stretching of the aromatic rings and the linear stretching of the C-C bonds within the rings, along with some contributions from the C-H vibrations in the methyl and methylene groups. Variations in the peak frequencies and bandwidths of these two Raman signals due to differing biological environments have been observed in melanin from different sources. The ability to acquire these unique in vivo melanin signals suggests that Raman spectroscopy may be a useful clinical method for noninvasive in situ analysis and diagnosis of the skin.

We have measured the Raman spectra of polycrystalline MgB 2 from 25 cm −1 to 1200 cm −1 . When the temperature was decreased below the superconducting transition temperature T c , we observed a superconductivityinduced redistribution in the electronic Raman continuum. Two pair-breaking peaks appear in the spectra, suggesting the presence of two superconducting gaps. Furthermore, we have analyzed the measured spectra using a quasi twodimensional model in which two s-wave superconducting gaps open on two sheets of Fermi surface. For the gap values we have obtained ∆ 1 = 22cm −1 (2.7 meV) and ∆ 2 = 50cm −1 (6.2 meV). Our results suggest that a conventional phonon-mediated pairing mechanism occurs in the planar boron σ bands and is responsible for the superconductivity of MgB 2 .

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The low energy Raman spectra of a Lal 83Sr»Cu04 single crystal have been measured at temperatures above and below T, . The redistribution of the electronic continua that occurs as a result of the opening of the superconducting gap has been observed. Based on the polarization dependence of the continua, it is concluded that the superconducting gap h(k) is anisotropic, with nodes along the (~1,~1) directions and maxima along the (0, + 1) and (~1,0) directions. The maximum pairing energy 2)A, ") is estimated to be about 7.7kT, .