The Raman spectra of the system NiSz -&e, are investigated for z = 0. OO,0.10,0.20,0.30, and 0.55, at room temperature and at temperatures below the point where the z = 0.55 sample suffers a resistivity change from semiconducting ( T 2 120 K) to metallic ( ! I ' 5 120 K). No qualitative or anomalous quantitative changes in the spectrum of the sample are found that could be associated with the anomaly in its transport properties. A mode of A, symmetry appears in the alloys which is absent from the spectrum of pure Xis,. This mode is successfully explained in terms of vibrations of S-Se pairs. Other modes decrease in frequency with increasing 'selenium concentration, a trend easily understood considering the increase in the unit cell volume with increasing z. Die Ramen-Spektren des Systems NiSs-Jh, (z = 0,OO; 0,lO; 020; 0,30 und 0,55) werden bei Zimmertemperatur und bei Temperaturen unterhalb des Punktes untersucht, wo die Probe mit z = 0,55 eine Widerstandsiinderung von halbleitend (T 2 120 K) zu metallisch ( T 120 K) zeigt. Es wird keine qualitative oder anomale quantitative Anderung im Spektrum der Probe gefunden, die mit der h o m a l i e in ihren Transporteigenschaften verkniipft werden kann. EineMode der Ag-Symmetrie in den Legierungen tritt 8 U f , die im Spektrum des reinen NiS, fehlt. Diese Mode liiI3t sich erfolgreich mit Schwingungen der SSe-Paare erklzren. Die Frequenzen an-dererModen nehmen mit steigender Selenkonzentration ab ; ein Trend der sich durch Beriicksichtigung der VergraSerung des Volumens der Einheitszelle mit steigendem z leicht erklaren liiI3t.
Raman and infrared spectra on well-staged graphite-AlC1, are reported for compounds with stages n = 1, 2, 4, and 8. Of significance is the absence of infrared-active modes for stage-1 graphite-A1C1, and the presence in stages 2, 4, and 8 of three infrared-active modes in the vicinity of the graphite E,"mode. The Raman-active modes in graphite-AlC13 behave similarly to the corresponding bounding-layer and interiorlayer graphitic modes in graphite=FeC1, with regard to the stage dependence of the peak frequencies and relative intensities.
Raman spectra of Br,, CI, and I, adsorbed on graphite, KBr and fused quartz substrates are reported. The results demonstrate that the process of adsorption is strictly related to the type of adsorbate. Different Raman modes were observed for each kind of molecule adsorbed on the substrates. With adsorbed 12, the continuum resonance Raman spectra for the fundamental solid I, and no frequencies due to adsorption were observed.
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