Raman diamond

Figure 12.20a shows the changes of the diamond Raman peak after oxidation in air at 430°C for 2, 6,17, 26, and 42 h. The corresponding average crystal sizes were determined by X-ray diffraction (see Fig. 12.18c) and are 4.8, 5.2, 5.5, 6.5, and 7.0 nm, respectively. The confinement-induced asymmetry of the Raman peak decreases with increasing oxidation time, leading to a narrower diamond line (Fig. 12.20a). The intensity of the shoulder around 1,250 cm also decreases with oxidation time, suggesting a possible correlation with the crystal size.

A clear diamond Raman spectrum with a sharp peak at 1332 cm... 

Since CVD diamond is synthesized under conditions in which graphite synthesis is competitive, in many cases, a non diamond component may be incorporated in its amorphous form. The film quality was confirmed by Raman spectroscopy because it is very sensitive to graphitic and amorphous carbon (a C) components the Raman scattering intensity of graphite or a C is about 30 times greater than that of diamond. Raman spectroscopic measurements were carried out using an Ar+ laser (wavelength =... 

Plenary 14. A K Ramdas et al, e-mail address akr phYsics.purdue.edu (RS). Electronic RS studies of doped diamond as potential semiconducting materials. A Raman active Is (p3 2) ls (Pi/2 transition of a hole... 

New metliods appear regularly. The principal challenges to the ingenuity of the spectroscopist are availability of appropriate radiation sources, absorption or distortion of the radiation by the windows and other components of the high-pressure cells, and small samples. Lasers and synchrotron radiation sources are especially valuable, and use of beryllium gaskets for diamond-anvil cells will open new applications. Impulse-stimulated Brillouin [75], coherent anti-Stokes Raman [76, 77], picosecond kinetics of shocked materials [78], visible circular and x-ray magnetic circular dicliroism [79, 80] and x-ray emission [72] are but a few recent spectroscopic developments in static and dynamic high-pressure research. 

Chronister E L and Crowell R A 1991 Time-resolved coherent Raman spectroscopy of low-temperature molecular solids in a high-pressure diamond anvil cell Chem. Phys. Lett. 182 27... 

Raman spectroscopy of films [INFRARED TECHNOLOGY AND RAMAN SPECTHOSCOPY - RAMAN SPECTHOSCOPY] (Vol 14) Diamond Alizarine Black SN [3258-74-0]... 

Raman Microspectroscopy. Raman spectra of small soflds or small regions of soflds can be obtained at a spatial resolution of about 1 p.m usiag a Raman microprobe. A widespread appHcation is ia the characterization of materials. For example, the Raman microprobe is used to measure lattice strain ia semiconductors (30) and polymers (31,32), and to identify graphitic regions ia diamond films (33). The microprobe has long been employed to identify fluid iaclusions ia minerals (34), and is iacreasiagly popular for identification of iaclusions ia glass (qv) (35). 

Because Raman spectroscopy requires one only to guide a laser beam to the sample and extract a scattered beam, the technique is easily adaptable to measurements as a function of temperature and pressure. High temperatures can be achieved by using a small furnace built into the sample compartment. Low temperatures, easily to 78 K (liquid nitrogen) and with some diflSculty to 4.2 K (liquid helium), can be achieved with various commercially available cryostats. Chambers suitable for Raman spectroscopy to pressures of a few hundred MPa can be constructed using sapphire windows for the laser and scattered beams. However, Raman spectroscopy is the characterizadon tool of choice in diamond-anvil high-pressure cells, which produce pressures well in excess of 100 GPa. ... 

Recent developments in Raman equipment has led to a considerable increase in sensitivity. This has enabled the monitoring of reactions of organic monolayers on glassy carbon [4.292] and diamond surfaces and analysis of the structure of Lang-muir-Blodgett monolayers without any enhancement effects. Although this unenhanced surface-Raman spectroscopy is expected to be applicable to a variety of technically or scientifically important surfaces and interfaces, it nevertheless requires careful optimization of the apparatus, data treatment, and sample preparation. 

Information exists about the use of measuring cells made entirely of diamond or graphite with or without embedded diamond windows. Diamond cells were used, for instance, by Toth and Gilpatrick [333] in the investigation of the Nb(IV) spectrum in a LiF - BeF2 molten system at 550°C. Windowless graphite cells for the IR spectroscopy of melts were developed by Veneraky, Khlebnikov and Deshko [334]. Diamond, and in some cases windowless sapphire or graphite micro-cells, were also applied for Raman spectroscopy measurements of molten fluorides. 

The TED and XRD patterns revealed that the deposit is not amorphous carbon but nanocrystalline diamond. Nonetheless, the 514-nm excited Raman spectra do not exhibit a clear diamond peak at 1332 cm though the peak due to the sp -bonded carbon network appears at 1150 cm The Raman cross section of the sp -bonded carbon network with visible excitation is resonantly enhanced [43, 48-50]. It consequently makes the 1332 cm diamond peak overlap with the peaks due to sp -bonded carbon. 

The 244-nm excited Raman spectra of t-aC films exhibit the appearance of the peak at 1150 cm and the increase in the intensity proportional to the amount of sp bonding in the films [50, 51]. However, the diamond peak at 1332 cm is enhanced in this study because the deposit obtained is not amorphous carbon but nanocrystalline diamond. The peak at --1150 cm is probably disappearing because of the striking enhancement of the diamond peak at 1332 cm T... 

Raman spectroscopy A nondestructive method for the study of the vibrational band structure of materials, which has been extensively used for the characterization of diamond, graphite, and diamond-like carbon. Raman spectroscopy is so far the most popular technique for identifying sp bonding in diamond and sp bonding in graphite and diamond-like carbon. 

The goal of our investigations was to characterise the morphology of the sample, and to determine the size and location of the PTFE and silicone oil phases by different methods [46,47], For phase characterization using Raman microscopy, no special sample preparation was necessary. For FTIR imaging, microtomed sections (5 pm in thickness) had to be prepared by cutting the sample with a diamond knife at — 80°C ("cryo-microtomy") to prevent smearing and to obtain flat surfaces. 

D.S. Knight, W.B. White, Characterization of diamond films by Raman spectroscopy, Journal of Materials Research, 4 (2011) 385-393. 

M. Khayyat, G. Banini, D. Hasko, and M. Chaudhri, Raman microscopy investigations of structural phase transformations in crystalline and amorphous silicon due to indentation with a Vickers diamond at room temperature and at 77 K, J. Phys. D—Appl. Phys. 36, 1300-1307 (2003). 

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