An improved calibration curve of the pressure shift of the ruby R1 emission line was obtained under quasi-hydrostatic conditions in the diamond-window, high-pressure cell to 800 kbar. Argon was the pressure-transmitting medium. Metallic copper, as a standard, was studied in situ by X ray diffraction. The reference pressure was determined by calibration against known equations of state of the copper sample and by previously obtained data on silver.

Calibration of the ruby pressure gauge to 800 kbar under quasi-hydrostatic conditions

The status of experimental tests of general relativity and of theoretical frameworks for analyzing them is reviewed and updated. Einstein’s equivalence principle (EEP) is well supported by experiments such as the Eotvos experiment, tests of local Lorentz invariance and clock experiments. Ongoing tests of EEP and of the inverse square law are searching for new interactions arising from unification or quantum gravity. Tests of general relativity at the post-Newtonian level have reached high precision, including the light deflection, the Shapiro time delay, the perihelion advance of Mercury, the Nordtvedt effect in lunar motion, and frame-dragging. Gravitational wave damping has been detected in an amount that agrees with general relativity to better than half a percent using the Hulse-Taylor binary pulsar, and a growing family of other binary pulsar systems is yielding new tests, especially of strong-field effects. Current and future tests of relativity will center on strong gravity and gravitational waves.

/pdf/the-confrontation-between-general-relativity-and-experiment-5dqdube5p9.pdf

The Confrontation Between General Relativity and Experiment

As the technology for diamond film preparation by plasma-assisted CVD and related procedures has advanced, Raman spectroscopy has emerged as one of the principal characterization tools for diamond materials. Cubic diamond has a single Raman-active first order phonon mode at the center of the Brillouin zone. The presence of sharp Raman lines allows cubic diamond to be recognized against a background of graphitic carbon and also to characterize the graphitic carbon. Small shifts in the band wavenumber have been related to the stress state of deposited films. The effect is most noticeable in diamond films deposited on hard substrates such as alumina or carbides. The Raman line width varies with mode of preparation of the diamond and has been related to degree of structural order. The Raman spectrum of hexagonal diamond (lonsdaleite) is distinct from that of the cubic diamond and allows it to be recognized.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0884291400004441

Characterization of diamond films by Raman spectroscopy

The field of viscous liquid and glassy solid dynamics is reviewed by a process of posing the key questions that need to be answered, and then providing the best answers available to the authors and their advisors at this time. The subject is divided into four parts, three of them dealing with behavior in different domains of temperature with respect to the glass transition temperature, Tg , and a fourth dealing with ‘‘short time processes.’’ The first part tackles the high temperature regime T.Tg ,i n which the system is ergodic and the evolution of the viscous liquid toward the condition at Tg is in focus. The second part deals with the regime T;Tg , where the system is nonergodic except for very long annealing times, hence has time-dependent properties ~aging and annealing!. The third part discusses behavior when the system is completely frozen with respect to the primary relaxation process but in which secondary processes, particularly those responsible for ‘‘superionic’’ conductivity, and dopart mobility in amorphous silicon, remain active. In the fourth part we focus on the behavior of the system at the crossover between the low frequency vibrational components of the molecular motion and its high frequency relaxational components, paying particular attention to very recent developments in the short time dielectric response and the high Q mechanical response. © 2000 American Institute of Physics.@S0021-8979~00!02213-1#

https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1065&context=mse_pubs

Relaxation in glassforming liquids and amorphous solids

The authors reported on investigation of the thermal conductivity of graphene suspended across trenches in Si∕SiO2 wafer. The measurements were performed using a noncontact technique based on micro-Raman spectroscopy. The amount of power dissipated in graphene and corresponding temperature rise were determined from the spectral position and integrated intensity of graphene’s G mode. The extremely high thermal conductivity in the range of ∼3080–5150W∕mK and phonon mean free path of ∼775nm near room temperature were extracted for a set of graphene flakes. The obtained results suggest graphene’s applications as thermal management material in future nanoelectronic circuits.

/pdf/extremely-high-thermal-conductivity-of-graphene-prospects-25qgwo9zzw.pdf

Extremely high thermal conductivity of graphene: Prospects for thermal management applications in nanoelectronic circuits

All minerals have regions of strong absorption of electromagnetic
radiation in the ultraviolet, visible, or infrared portions of the spectrum, which arise from electronic and vibrational transitions of the various ions
in the minerals. The study of the ultraviolet spectra of minerals is a comparatively
neglected subject because the absorption bands in the ultraviolet
are so intense that it is experimentally difficult to prepare samples
thin enough to transmit the amount of light necessary for measurements
of the spectra. The study of the infrared spectra of minerals is an important
and expanding field, and is the topic of several of the following chapters.
The region in between, the visible and near-infrared portions of the spectrum,
extending from 400 to 2500 nm (0.4-2.5 µm), is the spectral region
discussed in this chapter.

Absorption spectroscopy of ionic and molecular units in crystals and glasses

Chemical disproportionation of ferrous iron-bearing phases to an equilibrium mixture of ferric iron-bearing phases plus metallic iron is stabilized at high pressures. The effect is observed in olivine, and is the basis of a model of the earth’s mantle and core that is evolved from a primitive earth. The model is consistent with an equilibrium process of formation of the earth, and satisfies known physical properties of materials that are suitable for the mantle.

Disproportionation Equilibrium in Iron-Bearing Systems at Pressures above 100 Kbar with Applications to Chemistry of the Earth’s Mantle

http://link.springer.com/content/pdf/10.1007/978-94-009-7867-6_25.pdf

Iron-Magnesium Fractionation Model for the Earth

Apollo 16 rocks contain rustlike alteration. A mass of rust-colored, iron-rich crystals forming a grain 30 µm in diameter in rock 66095 has been identified by x-ray diffraction as akaganeite (β FeOOH). Other altered polycrystalline masses of less diameter are found associated with native FeNi metal grains. Akaganeite is known to occur in meteorite specimens, resulting from the oxhydration of lawrencite (FeCl 2 ) and native FeNi upon exposure to water vapor. The occurrence of akaganeite in the Apollo 16 rocks is essentially the same as in meteorites, and a similar process of alteration in an oxidizing environment is posulated for its origin. All or at least most of the akaganeite formed as a direct result of contamination by terrestrial water vapor of FeCl 2 -bearing lunar rocks.

Identification of the Hydrated Iron Oxide Mineral Akaganéite in Apollo 16 Lunar Rocks

A new mineral (approximately Fe0.5Mg0.5Ti2O5) related to the pseudobrookite series has been discovered in section 10071,28. Electron-probe analyses for this mineral, a coexisting ilmenite, and a chromian ulvospinel-ilmenite assemblage in section 10020,40 indicate crystallization under highly reducing conditions. Analytical and optical absorption studies of the olivine in 10020 show it to contain unusually high Cr (1400 parts per million) probably as Cr2+.

https://science.sciencemag.org/content/sci/167/3918/613.full.pdf

Peter M. Bell

Papers

Absorption spectroscopy of ionic and molecular units in crystals and glasses

Disproportionation Equilibrium in Iron-Bearing Systems at Pressures above 100 Kbar with Applications to Chemistry of the Earth’s Mantle

Iron-Magnesium Fractionation Model for the Earth

Identification of the Hydrated Iron Oxide Mineral Akaganéite in Apollo 16 Lunar Rocks

Iron-titanium oxides and olivine from 10020 and 10071.