C. Y. She

STRESS‐DEPENDENT RAMAN FREQUENCY AND LINEWIDTH IN α‐QUARTZ

The experimental results of the stress‐dependent frequency and linewidth of two E (128 cm−1, 398 cm−1) and three A1 (207 cm−1, 352 cm−1, 466 cm−1) Raman‐active vibrations in α‐quartz are reported. A qualitative explanation in terms of anharmonic deformation potential is given.The experimental results of the stress‐dependent frequency and linewidth of two E (128 cm−1, 398 cm−1) and three A1 (207 cm−1, 352 cm−1, 466 cm−1) Raman‐active vibrations in α‐quartz are reported. A qualitative explanation in terms of anharmonic deformation potential is given.

Comparison of fifth and third harmonic conversion in helium

Abstract Fifth and third harmonic conversion in helium are compared experimentally and theoretically. Conversion to the fifth harmonic is observed to exceed conversion to the third by about an order of magnitude, in good agreement with theoretical expectations. A comparison of the saturation behavior of each harmonic at high pump powers is made and implications concerning the physical processes responsible for the observed saturation of the fifth harmonic are described.

Raman study of structural transformations of titania coatings induced by laser annealing

The first microscopic investigation of laser annealing of optical coatings is reported. Amorphous TiO2 coatings were ion sputtered onto Si wafers at room temperature. We show, using Raman spectroscopy, that upon laser annealing, the amorphous coatings were transformed into microcrystals of anatase structure at lower laser intensity and into a mixture of anatase and rutile structures at higher intensity.

Simultaneous determination of velocity, turbulence and particle concentration of a turbulent flow using laser cross-beam photon-correlation spectroscopy

Abstract A turbulent velocity model is proposed to describe certain types of turbulent flows. An expression of the photon correlation function for laser cross-beam light scattering based on this model is presented, and it is found to give excellent agreement with experimental data. With least-square fitting, the measured spectrum allows the simultaneous determination of the mean flow velocity, turbulent velocity, and the number of scatterers.

Raman Spectra of α Quartz Under Uniaxial Stress

The experimental results of the stress‐dependent frequency and linewidth of two E and three A1 Raman active vibrations in α quartz are reported and their behavior is qualitatively discussed. The observed nonmonotonic frequency dependence of the stress induced shifts of the A1 lines can be understood based on the proposed modified valence‐force model that includes the effects of an anharmonic potential and the applied stress.

Measurement of flow and turbulence distribution of a free jet by laser photon correlation spectroscopy

Abstract The flow and turbulence profile of a free jet is reported by remote sensing techniques using laser Doppler effect and photon correlation spectroscopy.

Line-shape parameters of the Raman lines of chloro-, bromo-, and iodobenzene

Abstract High-resolution Raman spectra have been measured of chloro-, bromo-, and iodobenzene for line shifts up to 1600 cm−1 and several new lines were resolved. The line-shape parameters and depolarization ratios of most of these lines are reported here for the first time. The 1595 cm−1 benzene E2g doublet was resolved into the A1 and B1 monohalogen substituted lines. In going from bromoto iodobenzene a reversal in the A1-B1 line intensities was observed.

Laser-Excited Raman Spectroscopy

The cw gas laser used as the excitation source has been responsible for great changes in Raman spectroscopy. An introduction to laser-excited Raman spectroscopy is presented with the purpose being to minimize mathematical formalism and to provide a physical insight into the techniques.

Anomalous light scattering at the ferroelectric phase transition of KH2PO4

Abstract The temperature-dependent scattered light intensity accompanying the ferroelectric phase transition of KH 2 PO 4 is presented as an isofrequency-temperature scan. The temperature dependence of the data is shown to be better fit to the coupled harmonic oscillator model than to the single overdamped oscillator. This mode of data presentation also displays the anomalous light scattering near the phase transition.