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Brillouin scattering and x-ray photoelectron spectroscopy (XPS) have been utilized to characterize Ge+-implanted thermal SiO2 layers on a Si substrate with subsequent annealing at 500 °C and 1100 °C. Sputtering depth profiling in conjunction with XPS studies have been applied to identify the chemical state of elemental Ge and GeO2 precipitations in the SiO2 matrices. The presence of a subsurface GeOx zone as predicted in kinetic 3-dimensional lattice simulations has been confirmed. It is concluded that the intermediate step of Ge oxide formation seems necessary for the creation of Ge nanoclusters. The Ge atomic concentrations obtained from XPS were used to compute the bulk and shear moduli, and consequently the surface acoustic wave (SAW) velocities, for the Ge/GeO2/SiO2 systems. These calculations confirm the character of SAW velocity softening as determined from the Brillouin scattering investigations. [ABSTRACT FROM AUTHOR]

Measurements of absorption in the fundamental (4000 to 5000 cm-1) vibrational band of H2 have revealed new features in the collision-induced spectrum which attain their maximum intensity under near-critical conditions (Tc=32.98 K for para-H2). The new features are relatively sharp ‘‘spikes’’ (FWHM≊5 cm-1) which occur at the frequencies of the Q1(0) and/or Q1(1) transitions, and the effect is most prominent in pure para-H2. The behavior of these features as a function of temperature and of ortho-/para-H2 ratio has been investigated, they have also been detected in the spectrum of D2 near the critical point. An interpretation is proposed on the basis that long-lived spatial fluctuations in density give rise to a spoiling of the normally active mechanism of destructive intercollisional interference. [ABSTRACT FROM AUTHOR]

Investigates surface-acoustic-wave propagation in ion-implanted gallium phosphide by means of high-resolution Brillouin spectroscopy. Variation of the acoustic-wave velocity with dose; Details of the Brillouin scattering experimental geometry; Results of annealing studies.

Presents a study which identified the surface acoustic modes in gallium phosphide crystals. Utilization of the high-contrast Brillouin spectroscopy technique; Mechanisms for the interaction of light with the surface; Measurements of scattering.

The elastic constants of ice VI have been determined at -2 °C and 7.2 kbar by single crystal Brillouin spectroscopy. The adiabatic elastic moduli were found to be C11=26.8, C12=14.5, C13=12.8, C33=26.2, C44=6.3, and C66=10.4×104 bar, within approximately 1.5%. Large (125 mm3) single crystals were grown in a high pressure cell and in situ Brillouin spectra were collected at various crystal orientations about the laboratory z-axis. Ice VI crystals were oriented, while under pressure, by using the birefringent properties and Brillouin spectral behavior. Several polycrystalline elastic properties are derived using the bulk adiabatic moduli and a comparison with previous results is made. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Brillouin spectroscopy has been used to determine the adiabatic elastic constants of ice III at -20 °C and 2.2 kbar. A new technique was used to grow large single crystals. The bulk adiabatic moduli were found to be C11=153.7, C12=99.5, C13=65.1, C33=115.5, C44=44.6, C66=56.8 kbar. An averaging method was used in conjunction with these constants to determine longitudinal and transverse velocities and elastic moduli for isotropic polycrystalline aggregates and compared to previous values. This work is now being extended to ice II, IV, V, and VI. [ABSTRACT FROM AUTHOR]

The elastic constants and elasto-optic coefficient ratios of the orientationally disordered β phase of C2F6 have been determined using the technique of high resolution Brillouin spectroscopy. Just below the triple point, at 169 K, the values of the elastic constants (in units of kbar) are C11=26.99±0.10, C12=19.32±0.10, and C44=4.44±0.04. The temperature dependence of all three elastic constants was also determined and appears to be linear for the temperature range investigated, with ΔC11/ΔT=-0.335±0.010, ΔC12/ΔT=-0.236±0.010, and ΔC44/ΔT=0.005±0.011 kbar/K. Values of the ratios of acoustic velocities in high symmetry directions in the crystal indicate near perfect elastic isotropy and that moderately strong rotation–translation coupling is present in β-C2F6. [ABSTRACT FROM AUTHOR]

The technique of Brillouin spectroscopy has been used to determine the full set of adiabatic elastic constants of the orientationally disordered rhombohedral Ib phase of CCl4. The values of the elastic constants at 247.7 K are C11=45.4, C12=29.2, C13=27.3, C14=-1.2, C33=43.3 and C44=9.5 (in units of kbar). This system is elastically quite isotropic and can be closely approximated by hexagonal symmetry. The bulk modulus (33.5 kbar) is almost identical to that of the metastable orientationally disordered cubic Ia phase of CCl4. [ABSTRACT FROM AUTHOR]

The longitudinal and transverse speeds of sound of ice Ih, II, III, V, and VI have been measured by Brillouin spectroscopy in the range 0–10 kbar at -35.5 °C. The bulk adiabatic moduli derived from these measurements are 138.9, 98.7, 141.9, and 181.4 kbar for ice II, III, V, and VI, respectively, at pressures of 2.83, 2.76, 4.80, and 7.77 kbar, respectively. The isothermal compressions of the five phases have been measured directly by the contraction of a sample that was confined to a stainless-steel tube. [ABSTRACT FROM AUTHOR]

The technique of Brillouin spectroscopy has been used to determine the adiabatic elastic constants, including their temperature dependence, and the elasto-optic coefficient ratios of single crystals of the metastable orientationally disordered phase Ia of CCl4. The values of the elastic constants at 244.1 K are C11=35.7, C12=31.6, and C44=11.1 (in units of kbar) and the elasto-optic coefficient ratios are P12/P11=0.85 and P44/P11=0.22. The elastic constants results suggest that there is strong rotation–translation coupling in the k=0 acoustic wave vector regime and that this coupling is likely responsible for the metastability of the fcc phase Ia with respect to the rhombohedral phase Ib. [ABSTRACT FROM AUTHOR]

The technique of Brillouin spectroscopy has been used to determine the adiabatic elastic constants of single crystals of the orientationally disordered phase (phase I) of CBr4 .The values of the elastic constants at 333 K are C11 =42.2, C12 =33.6, and C44 =16.1 (in units of kbar) and suggest that there is strong rotation–translation coupling in the k=0 acoustic wave vector regime. Because x-ray Laue diffraction was not possible in solid CBr4 , the necessary orientation of the single crystals was determined by also using the Brillouin scattering spectra. [ABSTRACT FROM AUTHOR]

The adiabatic elastic constants of single crystals of ice Ih from the Mendenhall Glacier, and the longitudinal and transverse speeds of sound of polycrystalline ice aggregates, have been measured in the range 0–2.8 kbar at -35.5 °C by Brillouin spectroscopy. The ice was held in a 10 kbar optical cell that allowed the sample to be rotated under loads of up to 10 kbar about one axis from outside the cell. The elastic constants C11, C12, C13, C33, and C44, and the bulk modulus are quadratic in the pressure range 0–2.8 kbar. [ABSTRACT FROM AUTHOR]

The technique of high resolution Brillouin spectroscopy has been used to determine the adiabatic elastic constants and the elasto-optic coefficient ratios of oriented single crystals of SF6 at temperatures near the triple point. The values of the elastic constants at 221.0 K are C11 =34.1, C12=22.2, and C44=13.2 (in units of kbar) and the elasto-optic coefficient ratios are P12 /P11 =0.92 and P44 /P11 =0.09. The temperature dependences of the elastic constants were determined and were found to be linear down to 187.0 K with ΔC11 /ΔT having a particularly large value of -0.46 kbar K-1 . [ABSTRACT FROM AUTHOR]

The technique of high resolution Brillouin spectroscopy has been used to determine the adiabatic elastic constants and the elasto-optic coupling (Pockels) coefficient ratios of oriented single crystals of (solid I) ND3 at temperatures near the gas–liquid–solid triple point. The values of the elastic constants at 196.0 K are C11=83.3, C12=44.0, and C44=49.6 (in units of kbar) with an estimated absolute uncertainty of ±2%. The values of the elasto-optic coefficient ratios are P12/P11=0.90 and P44/P11=0.16 for ND3 and 0.89 and 0.16 for NH3, respectively. Other than that expected from the mass ratio, no significant isotopic differences are evident. [ABSTRACT FROM AUTHOR]

The technique of high resolution Brillouin spectroscopy has been used to determine the adiabatic elastic constants of oriented single crystals of (solid I) NH3 at temperatures near the triple point. The values obtained at 194.2 K were C11=81.1, C12=43.7, and C44=48.2 (in units of kbars) with an estimated absolute uncertainty of ±2%. No evidence for acoustic attenuation near the melting curve was found. [ABSTRACT FROM AUTHOR]

The technique of Brillouin spectroscopy has been used to determine the adiabatic elastic constants of oriented single crystals of α-CO at temperatures very close to the α–β phase transition. The values of the elastic constants at 60.9 K are c11=2.41, c12=1.44, and c44=1.06 (in units of 109 N m-2) and suggest that the k=0 acoustic phonon behavior is almost identical to that in a rare gas solid. [ABSTRACT FROM AUTHOR]