PRE-MELTING MODE IN THE DISORDERED KNO_3 CRYSTAL OBSERVED BY THE LOW-FREQUENCY RAMAN SCATTERING(Session I : Cross-Disciplinary Physics, The 1st Tohwa University International Meeting on Statistical Physics Theories, Experiments and Computer Simulations)

この論文は国立情報学研究所の電子図書館事業により電子化されました。On heating, potassium nitrate, KNO_3 undergoes a structural phase transition from the orthorhombic structure (phase II) to the trigonal structure (phase I) at 403 K(T_c) and melts at 606 K(T_m). The central peak in low-frequency Raman scattering spectra of KNO_3 was studied from room temperature up to 130 K above the melting point T_m. A drastic growth was observed with increasing temperature below and above T_m. The spectra were numerically analyzed and the results revealed that the central peak of KNO_3 consists of two spectral components; one is common between the solid state phase I and the molten state, and the other is sensitive for melting process

Raman lasing and cascaded coherent anti-Stokes Raman scattering of a two-phonon Raman band

Raman lasing of a two-phonon Raman band in the anti-Stokes side is demonstrated. Two femtosecond light pulses with identical wavelengths are irradiated onto a SrTiO3 crystal in a cross-beam configuration. Under low excitation power, several wave-mixing signals with identical wavelengths are emitted. When the power exceeds a critical value, cascaded coherent anti-Stokes Raman scattering (CARS) signals are emitted, the frequency step of which is coincident with that of the strongest two-phonon Raman band of 2TO2

Anomaly of the Raman Linewidth of the Internal v2 Mode near the Phase Transition Point of K3D(SO4)2

The linewidth of the internal mode ν 2 of SO 4 2- ion of the antiferroelectric K 3 D(SO 4 ) 2 shows the anomalous broadening with lowering temperature near the phase transition point. The broadening is well explained by a mechanism resembling the motional narrowing phenomenon in the nuclear magnetic resonance theory. The characteristic time of the motion of deuteron in a hydrogen bond is estimated to be on the order of 10 -13 s

Raman Scattering Study of K3H(SO4)2 and K3D(SO4)2 Single Crystals

Raman scattering from single crystals of K 3 H(SO 4 ) 2 and its deuterated analogues has been observed at 295 and 45 K. The spectra do not depend on the scattering geometries. Scarcely any effect of deuteration on frequencies was noted for most of the Raman lines. The Raman lines of the internal modes split into two peaks in the ordered phase of DKHS. The splitting is attributed to the ordering of deuterons

Central Peak of Ferroelectric LiH3(SeO3)2 near the Melting Point Studied by Raman Scattering

The central peak of the Raman spectrum of ferroelectric LiH3(SeO3)2 was observed as a function of temperature from 300 K to the melting point (383 K). With increasing temperature, the linewidth takes a minimum around 360 K and then shows anomalous broadening near the melting point. The temperature dependence of the linewidth is decomposed into two components; one component decreases linearly with temperature and the other one shows an anomalous increase toward the melting point. The analysis shows that the former is caused by the critical slowing down of the fluctuating electric polarizations in the ferroelectric phase and the latter by the activation of the ionic motion due to the premelting phenomena