Megabar high‐pressure cells for Raman measurements

Eremets, M. I.

doi:10.1002/jrs.1044

Cited by 75 publications

(63 citation statements)

References 19 publications

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“…This data fit is very similar to that from a study done by Popov, [3] which matches our 50 micron tip results up to 120 GPa and then nearly converges with Akahama et al [5] at much higher pressure. Unfortunately Eremets [1] did not report an equation with his fit to the data, but his results to appear to be consistent with this report. It is much more difficult to reconcile the data from Sun et al [2] and Vohra et al [18] between 60 and 200 GPa, since these two reports are the only ones to observe a linear dependence at ultrahigh pressures.…”

Section: Resultsmentioning

confidence: 57%

“…This had been suggested in a paper by Eremets [1] which reported no observable variation, but cautioned that the study was not systematic. This is likely the case for many of the other previous reports that do not observe a culet geometry dependence.…”

Section: Resultsmentioning

confidence: 90%

“…In recent years it has been demonstrated that the Raman shift of the diamond tip at the sample-culet interface can serve as an in-situ pressure sensor at very high pressures [1][2][3][4][5] and be a useful alternative to the ruby luminescence standard. [6][7] This newer technique has the benefit of always having in place a pressure sensor very near the sample.…”

Section: Introductionmentioning

confidence: 99%

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Raman shift of stressed diamond anvils: Pressure calibration and culet geometry dependence

Baer

Chang

Evans

2008

Journal of Applied Physics

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Abstract:The pressure dependence of the Raman shift of diamond for highly stressed anvils at the diamond-anvil sample interface has been measured for different culet shapes up to 180 GPa at ambient temperature. By using hydrogen samples, which constitute both a quasi-hydrostatic medium and a sensitive pressure sensor, some of the effects of culet and tip size have been determined. We propose that the divergent results in the literature can be partly ascribed to different anvil geometries. Experiments show increasing second order dependence of the diamond Raman shift with pressure for decreasing tip size. This is an important consideration when using the diamond anvils as a pressure sensor. Introduction:

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Section: Resultsmentioning

confidence: 57%

Section: Resultsmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

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Raman shift of stressed diamond anvils: Pressure calibration and culet geometry dependence

Baer

Chang

Evans

2008

Journal of Applied Physics

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“…Boppart, van Stratten, and Silvera 6 proposed using the high frequency wing extended to zero amplitude to determine and calibrate the pressure and this has been done by a number of researchers. [7][8][9][10][11] More recently Dubrovinskaia et al 12 have produced micrometer sized diamond markers embedded in the pressurization medium and provided a calibration to megabar pressures. Thus, we also include diamond markers in our study.…”

Section: Introductionmentioning

confidence: 99%

Pressure distribution in a quasi-hydrostatic pressure medium: A finite element analysis

Tempere

Silvera

2011

Journal of Applied Physics

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The highest quality pressures on samples in a diamond anvil cell (DAC) at high pressures are produced using quasi-hydrostatic pressurization media such as helium or hydrogen. In this paper we carry out a finite element analysis of pressure distributions in a DAC using helium and non-hydrostatic argon pressurization media. We find that samples and ruby chips are at substantially higher pressures than the pressurization media, although this is sharply reduced by using helium, which has a low yield strength for the shear modulus. The deviations in pressure of the different samples (and ruby) from the pressurization media differ and depend on their elastic constants. Our observations may account for the distribution of pressures in metallic markers found in a recent calibration of the ruby scale to high pressures.

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“…A technique that has previously been used includes the use of a pair of rotating chopper wheels synchronized to occlude short-lived radiation including the excitation laser light and short-lived fluorescence. This approach has been used to suppress diamond fluorescence in order to permit measurements of ruby fluorescence (the basis of the common pressure scale) above 100 GPa [13][14][15]. The latter process can be separated from the stressinduced diamond fluorescence because it is longer lived (5-20 ms).…”

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confidence: 99%

Pulsed laser Raman spectroscopy in the laser-heated diamond anvil cell

Goncharov

Crowhurst

2005

Review of Scientific Instruments

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We describe the design and operation of a spatially-filtered Raman/fluorescence spectrometer that incorporates a pulsed 532 nm laser excitation source and a synchronized and electronically gated CCD detector. This system permits the suppression of undesired continuous radiation from various sources by a factor of up to 50,000 providing the possibility of acquiring Raman signals at temperatures exceeding 5,000 K.We present performance comparisons of this system with that of a state-of-the-art conventional CW system using a 458 nm excitation source. We also demonstrate that the pulsed system is capable of suppressing an impurity-induced (single nitrogen defects) fluorescence in diamond, and further suggest that this capability can be used to suppress the stress-induced fluorescence in diamond that may appear at pressures near or above 150 GPa.Raman spectroscopy in combination with the DAC is an extremely versatile experimental tool. It is used to investigate the behavior under extreme pressure of many different material properties including vibrational, structural, electronic and elastic [1][2][3][4][5][6][7]. The results of these studies find application in various diverse disciplines including the geoand planetary sciences [1,2,4,5], fundamental physics and chemistry [2,6], and material science [7,8]. Under simultaneous conditions of extreme temperature further information concerning phase changes, chemical kinetics, superconductivity etc. may be obtained. Since the processes described above have very different characteristic time-scales, there is the possibility to separate them using various gated techniques. A technique that has previously been used includes the use of a pair of rotating chopper wheels synchronized to occlude short-lived radiation including the excitation laser light and short-lived fluorescence. This approach has been used to suppress diamond fluorescence in order to permit measurements of ruby fluorescence (the basis of the common pressure scale) above 100 GPa [13][14][15]. The latter process can be separated from the stressinduced diamond fluorescence because it is longer lived (5-20 ms). In another technique the detector is gated to collect the desired signal only when the excitation is present. It has been used for high-temperature Raman measurements at ambient pressure to suppress unwanted thermal radiation. Different types of apparatus have been used including mechanical choppers [16], pulsed lasers and a single-channel gated detector [17]. More recently, pulsed-laser excitation and gated CCD array detectors have been used for in situ Raman monitoring of diamond film growth [18]. Very recently, a pulsed-laser Raman system, which employs either a gated CCD detector or a Pockels switch has been developed, and Raman spectra in the 2000 K range have been reported [19]. However, in the case of the LHDAC even CW Raman measurements are very rare [20][21][22], while none at all in the time-resolved regime have, to our knowledge, been reported. We present here our pulsed Raman system and compar...

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Megabar high‐pressure cells for Raman measurements

Cited by 75 publications

References 19 publications

Raman shift of stressed diamond anvils: Pressure calibration and culet geometry dependence

Raman shift of stressed diamond anvils: Pressure calibration and culet geometry dependence

Pressure distribution in a quasi-hydrostatic pressure medium: A finite element analysis

Pulsed laser Raman spectroscopy in the laser-heated diamond anvil cell

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