scholarly journals The theory of the vibrations and the Raman spectrum of the diamond lattice

1948 ◽  
Vol 241 (829) ◽  
pp. 105-145 ◽  
Keyword(s):  
Raman Spectrum ◽  
Vibrational Spectrum ◽  
Frequency Shift ◽  
Raman Line ◽  
Elastic Constants ◽  
Lattice Dynamics ◽  
Ultra Violet ◽  
Force Constants ◽  
X Ray ◽  
Infra Red

The crystal structure of diamond was first determined by Bragg in 1913 from X-ray photographs; the carbon atoms are arranged at the apices and median points of interlinked tetrahedra. Born (1914) derived expressions for the three elastic constants of diamond in terms of two force constants related to the valency bonds between neighbouring atoms. But, at that time, the only experimental data available were the compressibility and the Debye characteristic temperature 0, and precise determination of the valence force constants was not possible. Meanwhile, investigation of the optical properties of diamond had produced evidence for the existence of two distinct types, one with an absorption band at 8 [i in the infra-red, the other transparent at this point. Robertson, Fox & Martin (1934) took up this problem and found that absorption in the infra-red is associated with absorption in the ultra-violet; diamonds transparent at 8y transmit much farther into the ultra-violet. Both types of diamond have Bragg’s tetrahedral structure, the same refractive index, specific gravity, dielectric constant and electron diffraction. Their infra-red spectra are identical up to 7y, and the frequency shift of the principal Raman line is the same. The derivation of the elastic constants was again considered by Nagendra Nath (1934). He extended the theory to include central forces between second neighbours in the lattice. He also suggested that the frequency shift of the principal Raman line corresponds to the relative vibration of the two carbon atoms in the unit cell, along the line joining their nuclei. Raman and his collaborators have recently (1941) put forward a new theory of lattice dynamics according to which the vibrational spectrum of a crystal consists of a few discrete lines. This is in direct contradiction to the quasi-continuous vibrational spectrum predicted by classical or quantum mechanics. On this new theory there are eight fundamental frequencies of vibration for diamond; the values of these frequencies are deduced from the observed specific heat, ultra-violet absorption and Raman spectrum, which, it is claimed, cannot be explained by ‘orthodox’ lattice dynamics. Raman (1944) has suggested that there are, not two, but four types of diamond, two with tetrahedral symmetry and two with octahedral symmetry depending on the electronic configurations, but X-ray analysis gives no indication of this and the attempts of his school to explain the observed infra-red spectra on the basis of their new lattice theory have been, up to now, unsuccessful.

scholarly journals The Raman spectrum of rock-salt

1946 ◽  
Vol 187 (1009) ◽  
pp. 188-196 ◽  
Keyword(s):  
Raman Spectrum ◽  
Rock Salt ◽  
Lattice Dynamics ◽  
Vibration Spectrum ◽  
Raman Effect ◽  
Frequency Shifts ◽  
Crystal Lattices ◽  
Absorption Frequency ◽  
Infra Red ◽  
Quartz Spectrograph

Using a non-luminescent crystal of rock-salt, a quartz spectrograph with a fine slit, and the 2536.5 A resonance radiations of mercury arc as exciter, the Raman effect in rock-salt has been studied. The spectrum exhibits nine distinct Raman lines with frequency shifts 135, 184, 202, 235, 258, 278, 314, 323 and 350 cm. -1 . The frequency shifts 235 and 184 cm. -1 representing conspicuous lines in the Raman spectrum agree as nearly as could be expected with the position of the two subsidiary infra-red absorption maxima observed by Barnes & Czerny with thin films of rock-salt. The principal infra-red absorption frequency of 163 cm. -1 is inactive in the Raman effect, but its octave is represented. The nature of the Raman spectrum to be expected is deduced on the basis of a theory due to Tamm, as also on the basis of another due to Fermi, the vibration spectrum of the rock-salt lattice being taken to be that worked out by Kellermann on the basis of the Born lattice dynamics. The results are altogether of a different nature from those actually observed experimentally in the present investigation. The conclusion is thus reached that the Born lattice dynamics does not correctly picture the vibration spectrum of the rock-salt lattice. On the other hand the observed facts, both in respect of Raman effect and infra-red absorption, fit into the theoretical picture provided by the dynamics of crystal lattices recently worked out by Sir C. V. Raman.

Schwingungsspektrum und Kristallstruktur des fünffach-koordinierten cis-Dioxo-dipicolinato-vanadat(V)-Anions / Vibrational Spectrum and Crystal Structure of the cis-Dioxo-dipicolinato-vanadium(V) Anion

1978 ◽  
Vol 33 (3) ◽  
pp. 265-267 ◽  
Author(s):  
Bernhard Nuber ◽  
Johannes Weiss ◽  
Karl Wieghardt
Keyword(s):  
Crystal Structure ◽  
Raman Spectrum ◽  
Vibrational Spectrum ◽  
Single Crystal ◽  
Diffraction Analysis ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
X Ray ◽  
Distorted Trigonal Bipyramid ◽  
Ir And Raman

Abstract cis-Dioxo-dipicolinato-vanadate(V), Crystal Structure, IR, Raman The crystal structure of Cs[V(O)2(dipic)]·H2O (dipic = pyridine-2,6-dicarboxylate) has been determined by single crystal x-ray diffraction analysis. The compound crystallizes in the monoclinic space group P21/a, with cell constants a =737.8(3), 6=1917.5(5), c = 792.9(3) pm, β= 94.87(6)°, and Z = 4. The geometry about vanadium is a distorted trigonal bipyramid containing a cis-dioxo moiety (∢ O-V-O 109.9(3)°, V=O bond lengths 161.0(6) and 161.5(6) pm). Vibrational absorptions νs(V - 0) and νas(V=O) were found at 956 and 947 cm-1 in the IR and Raman spectrum, resp.

X-ray Raman scattering on polycrystalline graphite in the scattering angle range 0–120°

1983 ◽  
Vol 61 (4) ◽  
pp. 629-632 ◽  
Author(s):  
Z. I. Kavogli ◽  
D. K. Leventouri ◽  
C. N. Koumelis
Keyword(s):  
Raman Spectrum ◽  
Raman Scattering ◽  
Raman Line ◽  
Scattering Angle ◽  
X Ray ◽  
Peak Intensity ◽  
Polycrystalline Graphite

X-ray Raman scattering was studied on polycrystalline graphite for various scattering angles in the range 0–120°. A mosaic graphite spectrometer without collimators and Crkβ radiation were used.The shape of the Raman spectrum depended slightly on the scattering angle. The peak intensity of the Raman line increases with scattering angle but in a different way to that resulting from the calculation of Mizuno and Ohmura. Additional components were observed in the spectrum on both sides of the Raman line.

ON THE THERMAL EXPANSION OF METALS AT LOW TEMPERATURES

1961 ◽  
Vol 39 (2) ◽  
pp. 263-271 ◽  
Author(s):  
G. K. Horton
Keyword(s):  
Thermal Expansion ◽  
Elastic Constants ◽  
Lattice Dynamics ◽  
Nearest Neighbor ◽  
Force Constants ◽  
Central Force ◽  
Force Model ◽  
Lattice Thermal Expansion ◽  
Interionic Potential ◽  
The Ideal

A theory is developed which correlates the thermal expansion of crystals to the anharmonicity introduced into Born's lattice dynamics by allowing the force constants of the crystal to vary with volume. This is achieved by identifying the force constants with the elastic constants of the crystal by the method of long waves. It is then assumed that it is primarily the volume dependence of the elastic constants that give rise to their temperature variation. A central force nearest and next-nearest neighbor force model analogous to Leighton's is applied to copper. The values of the lattice thermal expansion coefficient and of Grüneisen's parameter are given as a function of the temperature and found to agree quite well with the latest experimental results. It is pointed out that the description of the interionic potential in metals by a two-body central force is certainly a serious oversimplification and that the theory is likely to be more realistic for, say, the ideal inert solid gases, as soon as the experimental data becomes available.

scholarly journals PELATIHAN PENGGUNAAN PERALATAN LABORATORIUM FISIKA MATERIAL DAN RISET BAGI GURU-GURU FISIKA SMA SE KOTA MANADO

2019 ◽  
Vol 11 (2) ◽  
Author(s):  
Donny R Wenas
Keyword(s):  
Fourier Transform ◽  
Ultra Violet ◽  
Energy Dispersive ◽  
Electron Microscopic ◽  
X Ray ◽  
Infra Red ◽  
Scanning Electron Microscopic ◽  
Scanning Electron ◽  
Microscopic Energy

Kemampuan melaksanakan kegiatan praktikum/demonstrasi dan mengembangkan materi pembelajaran berbasis laboratorium adalah salah satu kompetensi guru fisika. Peningkatan kemampuan tersebut akan meningkatkan daya saing lulusan siswa. Tujuan pelaksanaan kegiatan pengabdian pada masyarakat ini adalah: 1) memperkenalkan pengetahuan tentang laboratorium Fisika material dan Riset bagi guru Fisika SMA se kota Manado; 2) memberikan pelatihan keterampilan penggunaan peralatan laboratorium Fisika material dan riset bagi guru Fisika SMA se kota Manado; 3) menjelaskan manfaat karakterisasi peralatan laboratorium Fisika Material dan Riset bagi guru Fisika SMA se kota Manado; dan 4) menjalin kerja sama antara dunia kerja yaitu Sekolah dengan Perguruan Tinggi (UNIMA) agar tercipta keserasian tentang kebutuhan Sumber Daya Manusia dilapangan dan kurikulum yang diterapkan khususnya pada Program Studi Fisika FMIPA UNIMA. Metode yang dilakukan adalah ceramah, demonstrasi, peragaan, diskusi dan evaluasi. Kegiatan ini akan menghasilkan produk berupa buku panduan bagaimana dan apa yang harus dilakukan dalam mengoperasikan peralatan laboratorium fisika material dan riset. Buku panduan akan dirancang semenarik mungkin disertai gambar dan keterangan serta langkah-langkah dalam mengoperasikan alat laboratorium. Disamping buku panduan, akan dibuat juga buku ajar tentang konsep dan teori terkait dengan peralatan laboratorium fisika material dan riset serta artikel ilmiah. Berdasarkan kegiatan yang dilaksanakan, maka diperoleh hasil sebagai berikut: 1) para peserta (Guru fisika SMA) mengenal pengetahuan tentang spektroskopi UV-Vis (Ultra Violet Visible); 2) memahami pengetahuan tentang spektroskopi FTIR (Fourier Transform Infra red); 3) mengenal pengetahuan tentang SEM-EDX (Scanning Electron Microscopic-Energy Dispersive X-Ray Spectrometric); dan 4) mampu mengoperasikan alat spektrometer UV-Vis, FTIR, dan SEM-EDX.

LATTICE DYNAMICS OF NICKEL

1967 ◽  
Vol 45 (5) ◽  
pp. 1655-1660 ◽  
Author(s):  
S. P. Singh
Keyword(s):  
Experimental Data ◽  
Specific Heat ◽  
Debye Temperature ◽  
Density Of States ◽  
Elastic Constants ◽  
Lattice Dynamics ◽  
Vibration Spectrum ◽  
Force Constants ◽  
Effective Force ◽  
Good Agreement

The vibration spectrum of the nickel lattice has been calculated using the simple de Launay method with values for the effective force constants determined from published experimental data for the elastic constants. The density-of-states curve reproduces the same general features found by Birgeneau et al. (1964) using a fourth-neighbor model. The Debye temperature at 0 °K is found to be 474 °K in good agreement with the experimental value of 468 °K, and the calculated variation of the Debye temperature with temperature agrees quite well with that deduced from measurements of the specific heat.

scholarly journals Two types of diamond

1933 ◽  
Vol 232 (707-720) ◽  
pp. 463-535 ◽  
Keyword(s):  
Dielectric Constant ◽  
Refractive Index ◽  
Optical Properties ◽  
Polarized Light ◽  
Ultra Violet ◽  
The Other ◽  
X Ray ◽  
King's College ◽  
Infra Red ◽  
Ray Patterns

Among a number of diamonds supplied to us by Professor W. T. Gordon, of King’s College, London, one, by a fortunate chance, was found to differ from the rest in its infra-red spectrum. Having confirmed by various methods th at a large absorption band at 8 g. present in the spectrum of all the other diamonds, was absent in this particular one, we explored photographically the ultra-violet spectrum of all the diamonds then available, and found th at the stone which was transparent at 8 p. in the infra-red was also transparent from about X 3000 to X 2250 in the ultra-violet, the other diamonds being opaque beyond X 3000. At this stage, between two and three hundred diamonds were examined visually by means of a simple ultra-violet spectroscope with fluorescent eye-piece without another diamond transparent beyond X 3000 being found. Among other physical and optical properties examined in comparison, little difference was found between diamonds of the usual and the transparent type : their waterwhiteness, density, refractive index, dielectric constant, Raman frequency and the earlier X-ray patterns appeared the same. A difference in the crystalline condition was, however, noted, for the transparent diamond was made up of a large number of parallel laminae, and it was also more nearly isotropic when examined by polarized light than the others.

scholarly journals The vibration spectrum and molecular configuration of cyclohexane

1947 ◽  
Vol 190 (1021) ◽  
pp. 245-256 ◽  
Keyword(s):  
Dipole Moment ◽  
Raman Spectrum ◽  
Vibration Spectrum ◽  
Vibration Frequencies ◽  
Specific Heat Data ◽  
Molecular Configuration ◽  
X Ray ◽  
Physical Evidence ◽  
Infra Red ◽  
Heat Data

The physical evidence for the structure of the cyclohexane molecule (X-ray, electron diffraction, dipole moment, vibration spectra) is all in favour of the ‘chair’ configuration. The twelve vibration frequencies for the carbon skeleton of this model have been calculated, using a simple valency force field. There are eight distinct frequencies, four being doubly degenerate. The two force constants are evaluated from two of the Raman frequencies and used to calculate the remaining six frequencies. Five of these frequencies are found to agree with the observed frequencies to within 4%, while the sixth frequency is too low to be observed conveniently in the infra-red and is forbidden in the Raman spectrum. The value calculated (206 cm. -1 ) for this sixth frequency is, however, consistent with the specific heat data. The selection rules are shown to be obeyed by the assigned frequencies. The value for the C-C stretching force constant, viz. 3⋅7 x 10 5 dynes/cm. is considerably lower than that for the same bond in ethane, viz. 4.5 x 10 5 dynes/cm., indicating a weakening of the C-C bond in cyclohexane relative to ethane.

scholarly journals Further work on two types of diamond

1936 ◽  
Vol 157 (892) ◽  
pp. 579-593 ◽  
Keyword(s):  
Visible Region ◽  
Polarized Light ◽  
Ultra Violet ◽  
X Ray ◽  
Apparent Homogeneity ◽  
Infra Red ◽  
Ordinary Type ◽  
Constant Refractive Index

In the paper "Two Types of Diamond" many physical properties of diamond are described, and on p. 516 are collected features of difference and of similarity between the two types. Briefly, the ordinary type (Type 1) is characterized by greater apparent homogeneity, Type 2 having a mosaic structure but greater isotropy in polarized light; in infra-red absorption Type 1 has a strong band at 8 μ, this being absent in Type 2; in the ultra-violet Type 1 absorbs up to a point much nearer the visible region than Type 2 which is transparent nearly as far out as quartz; Type 1 has little, Type 2 a marked photo-conductivity; while the X-ray pattern exhibits slight differences interpreted as supporting the greater degree of mosaicness of Type 2. The two types were similar in respect of the electron diffraction, the Raman spectrum, tribo-luminescence, dielectric constant, refractive index, specific gravity, and colour.

The Vibrational Spectrum of Methyl isothiocyanate

1959 ◽  
Vol 12 (4) ◽  
pp. 601 ◽  
Author(s):  
AJ Costoulas ◽  
RL Werner
Keyword(s):  
Raman Spectrum ◽  
Vibrational Spectrum ◽  
Methyl Isothiocyanate ◽  
Infra Red ◽  
Parallel Band

Methyl isothiocyanate has been studied in the infra-red region from 10,000 to 250 cm-1 as vapour, solid, and melt, while the Raman spectrum has been recorded in the molten condition. The molecule is close to a symmetric top and the bands of the vapour exhibit contours generally similar to that type of molecule. A satisfactory assignment of all fundamentals has been made. Of interest is the pseudo-symmetric NCS stretching mode which has been assigned to the parallel band at 676 cm-1 in the vapour. In the Raman spectrum, the corresponding mode is observed as a strong polarized line at 656 cm-1.

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