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1.
Detailed Raman scattering data on brominated (SN)x crystals ranging in composition from (SNBr0.27)x to (SNBr0.55)x, and preliminary Raman data on [SN(ICI)0.125]x are discussed. The investigation involved a study under various conditions of temperature, pressure and levels of bromination, of the two primary Raman lines at 154 and 230 cm-1 in brominated (SN)x, which are polarized along the polymer axis direction. The analysis of the data is consistent with a model in which bromine enters the interfibrillar regions as Br-3 and the (SN)x lattice as Br2. Infrared data is also presented showing an appreciable decrease in intensity of the SN modes at 995 and 670 cm-1 on bromination. 相似文献
2.
The polarized Raman spectra of SrB4O7 (SBO) single crystals are studied in detail in the temperature range of 300–1273 K. The TO, LO, and IO phonon lines of A1, A2, B1, and B2 symmetries of rhombic SBO at 300 K are identified. The behavior of the Raman spectra of SBO crystals is studied upon heating up to their melting. The relation of Raman spectra with the structure of boron–oxygen fragments, as well as the transformation of spectra in the process of melting of SBO crystals, is discussed. 相似文献
3.
Low energy Raman scattering measurements on samples of K0.76Na0.24TaO3, K0.9Na0.1TaO3 and K0.75Li0.25TaO3 under hydrostatic pressures of up to 60 kbar supply confirming evidence to the hypothesis that the Na+ ions in these crystals are displaced from the centers of the sites they occupy. The pressure Raman experiments also reveal another second order Raman line interpreted as Raman scattering by two TA phonons at M. A line induced by the substitution of Na for K is found to have an energy about equal to the energy of this new second order Raman line. It is shown that if this is a resonant mode it must be an even mode. 相似文献
4.
We demonstrate a technique for directly measuring the quadratic Zeeman shift using stimulated Raman transitions. The quadratic Zeeman shift has been measured yielding Δν=1296.8±3.3 Hz/G2 for magnetically insensitive sublevels (5S1/2,F=2,mF=0→5S1/2,F=3,mF=0) of 85Rb by compensating the magnetic field and cancelling the ac Stark shift. We also measured the cancellation ratio of the differential ac Stark shift due to the imbalanced Raman beams by using two pairs of Raman beams (σ+, σ+) and it is 1:3.67 when the one-photon detuning is 1.5 GHz in the experiment. 相似文献
5.
The Raman spectrum of stage 1 europium intercalated graphite, EuC6, has been recorded at room temperature. EuC6 has a p(√3 × √3)R30° in-plane superlattice structure, the same as that of LiC6. The c-axis stacking sequences of EuC6 and LiC6 are different. The Raman spectrum of EuC6 exhibits a broad asymmetric Fano resonance peak at 1500 ± 5 cm-1, similar to that observed in MC8 (M = K, RbandCs). However, there is no evidence of any spectral feature around 580 cm-1 as what has been observed in MC8. Considering the Raman features of various graphite intercalation compounds in light of their superlattice structures, we suggest that: (1) The feature around 580 cm-1 is a characteristic associated only with the MC8p(2 × 2)R0° in-plane superlattice structure. It should originate from the M point phonons of pristine graphite, which become Raman active as predicted by phonon band structure calculations. (2) The continuous background in the spectra of EuC6 and MC8, which results in the Fano resonance peak at 1500 cm-1, is associated with the staggered stacking sequence. Stacking faults are easy to occur in crystals with staggered stacking sequences, but not in crystals with complete elliptical sequences. Therefore, a disorder induced continuum is observed in the Raman spectra of EuC6 and MC8, but not in that of LiC6. 相似文献
6.
Raman spectra of the orthorhombic (II) and high pressure (III) phases of titanium dioxide at pressures to 372 kbar and effects of temperature and hydrostatic pressure on Raman spectra of the tetagonal cassiterite-like phases of TiO2, GeO2 and SnO2 are described. At room temperature, the TiO2 II–III transition is sluggish, and metastable coexistence was observed from 200 to 300 kbar. The Raman spectra of TiO2-III imply that its primitive cell contains at least four formula units; however, the structure could not be established from the Raman spectra and available powder X-ray diffraction patterns.The temperature and pressure dependences of the spectrum of the tetragonal MO2 phases together with bulk moduli and thermal expansion data were used to evaluate the pure-volume and pure-temperature contributions to the isobaric temperature dependence of the Raman frequencies. Large anharmonicities in TiO2 are attributed to hybridization of the oxygen p states with the d states of the Ti ion. GeO2, where p-electron bonding is involved, is much less Enharmonic. 相似文献
7.
Raman scattering measurements of NiS2 is done and five optical phonon peaks are found. These peaks are assigned to Ag, Eg and 3Tg phonons which are all of the Raman active optical phonons in pyrite-type crystal. The results are compared with those of FeS2 and MnS2. 相似文献
8.
A one- and multiphonon Raman scattering study is performed for an extensive set of CdS1–xSex, Cd1–yZnyS, Cd1–yZnySe, and CdSe1–xTex nanocrystals to investigate the applicability of first- and second-order Raman spectra for the determination of the matrix-embedded ternary nanocrystal composition. For one-mode ternary systems both the LO and 2LO phonon frequencies in the Raman spectra are shown to be a good measure of the nanocrystal composition. For two-mode systems, the approaches based on the difference of the LO phonon frequencies (first-order Raman spectra) or double LO overtone and combination tone frequencies (second-order Raman spectra) as well as on the LO phonon band intensity ratios are analysed. The weak electron–phonon coupling in the II–VI nanocrystals and the polaron constant values for the nanocrystal sublattices are discussed. 相似文献
9.
Raman spectra of hexagonal layer compounds MoS2, MoSe2 and MoTe2 were excited by a HeNe laser (6328Å). All the Raman active long-wave-length phonon frequencies were determined. These are A1g, E12g, E1g and E2g. The frequencies decrease as we pass from sulphur to tellurium and the quasiacoustical mode E22g has the lowest frequency. A comparison of the results with infrared spectra shows that the i.r. active mode for E ⊥ C is degenerate with one of the Raman active modes in the basal plane for all the compounds. 相似文献
10.
Polarized Raman spectra of single crystals of lead diborate, PbB4O7 (PBO), are studied in detail at 300 K. The TO-, LO-, and IO-phonon lines of the A 1, A 2, B 1, and B 2 symmetries in the Raman spectra of this compound are assigned. Changes in the Raman spectra of the internal vibrations of boron–oxygen complexes upon transition from the crystalline to the glassy and the molten states of PBO are observed. On the basis of the obtained results, the regularities in the formation of boron–oxygen complexes in glasses, melts, and crystals of the PbO · 2B2O3, SrO · 2B2O3, and Li2O · 2B2O3. diborate compositions are analyzed. 相似文献
11.
12.
J.C. Deroche G. Graner Jørgen Bendtsen Svend Brodersen 《Journal of Molecular Spectroscopy》1976,62(1):68-79
The ν5 and ν3 Raman bands of CH2D2 have been recorded with a resolution of 0.35 cm?1. The ν3 state is well known from infrared studies. Three hundred twenty-nine transitions of the ν5 band were analyzed, assuming an unperturbed upper state, giving a standard deviation on the fit of the upper-state energies of 0.037 cm?1, The constants A, B, C, ΔJ, ΔJK, and ΔK differed significantly from the ground-state values, and ν5 was determined as 1331.41 ± 0.05 cm?1. This work represents the first complete analysis of the fine structure of a rotation-vibrational Raman band for an asymmetric rotor. The ν5 state could not be analyzed in infrared so this investigation, once more, demonstrates the usefulness of the Raman method. 相似文献
13.
Four one-phonon Raman lines have been found in CdIn2S4 (ZnIn2S4) spinels at 92 (72) cm-1, 186 (184) cm-1, 246 (253) cm-1, and 367 (372) cm-1 for incident photon energies well below the energy gap EG ~ 2.4 (2.2) eV at 300 K. For photon energies close to EG, the 367 cm-1 mode underwent a resonant enhancement in CdIn2S4 and four infrared active but Raman forbidden F1u modes appeared in the CdIn2S4 and ZnIn2S4 Raman spectra: TO modes at 226 (221) cm-1 and 309 (312) cm-1, and LO modes at 274 (272) cm-1 and 340 (342) cm-1. 相似文献
14.
A value of A0 = 5.1800 ± 0.0010 cm?1 for CH3Br has been determined from an analysis of the ν4 Raman band, based both on a direct fit of Q-branch frequencies and on ground state combination differences. The constants ν4, (Aζ)4, η44, and Ae = 5.2442 ± 0.0015 cm?1 were also determined. The equilibrium distance of the H atoms from the figure axis is calculated as 0.32077 ± 0.00005 Å. All the fundamental Raman bands of CH3Br were observed, and experimental results for the ν1, ν2 and ν5 bands are included. 相似文献
15.
《Journal of Physics and Chemistry of Solids》1986,47(9):913-917
KSbF6 has a tetragonal structure above 300 K, below 300 K. it is cubic and undergoes a phase transition at ∼ 3 kbar to a phase which is shown to be isostructural with that of rhombohedral CsSbF6. Conclusive evidence is found in the polarized Raman spectra of single crystals of rhombohedral CsSbF6 that they belong to the space group R3̄-C23i. The high-pressure Raman spectra of rhombohedral KSbF6, TlSbF6, and CsSbF6 are compared and cationic effects are discussed. 相似文献
16.
《Infrared physics》1987,27(4):227-232
The infrared and Raman spectra of the two phosphochromates M3PCr4O16 (M = K, NH4) have been recorded and analysed. The spectra could be interpreted on the basis of the vibrations of Cr-O-P, O-P-O and CrO3 groups. A large number of vibrational bands have been observed for each mode due to the existence of different Cr-O bond lengths. The anion is more distorted in potassium phosphochromate. The three ammonium groups are distinct. 相似文献
17.
Yu. E. Gorbaty G. V. Bondarenko 《Russian Journal of Physical Chemistry B, Focus on Physics》2012,6(8):873-877
The sensitivity of infrared (IR) absorption and Raman scattering (RS) spectra to hydrogen bonding in methanol is quantified by a comparative sensitivity factor, which can be expressed as the K = (I b /I ub )IR/(I b /I ub )RS, where the indices b and ub refer to H-bonded and unbound (free) OH groups, respectively. The resulting value for methanol, K ~ 20, is identical to that found previously for n-butanol, although the methods of measuring the degree of hydrogen bonding for these two alcohols were quite different. It is shown that, in some cases, Raman spectra can be converted to IR absorption spectra and vice versa. It is important for understanding differences in the shapes of OH stretching vibration bands in IR absorption and Raman spectra. 相似文献
18.
Adelbert Owyoung Peter Esherick Alan G. Robiette Robin S. McDowell 《Journal of Molecular Spectroscopy》1981,86(1):209-215
A near-Doppler-limited isotropic Raman spectrum of the symmetric stretching fundamental ν1 of 28SiH4 has been recorded between 2182.8 and 2187.0 cm?1 using high-sensitivity “quasi-cw” inverse Raman spectroscopy. The band exhibits compact, nonoverlapping J manifolds, which were measured from Q(0) through Q(13), plus a portion of Q(14). Since ν1 is in resonance with the nearby infrared-active stretch ν3, these two bands were analyzed simultaneously using the infrared frequencies of ν3 reported by Cabana, Gray, Robiette, and Pierre. The results confirm their analysis, in which several perturbation-allowed ν1 transitions were identified in the infrared, but the molecular constants for the v1 = 1 state are much better determined with the inclusion of the Raman data. At higher J, ν1 exhibits significant intensity perturbations due to a breakdown of the selection rule ΔN = 0; these have been quantitatively accounted for. 相似文献
19.
Yoshifumi Nishimura Akiko Y Hirakawa Masamichi Tsuboi 《Journal of Molecular Spectroscopy》1977,68(3):335-358
It has been shown that a Raman line of a nontotally symmetric vibration (b1g, b2g, or a2g) of a metalloporphyrin (D4h) can be caused, not only by a vibronic coupling between the first () and second () excited electronic states but also by a vibronic coupling within one of the electronic states (let us call the former the QS mechanism and the latter the QQ and/or SS mechanism). A simple formulation has been made for each of those different mechanisms, so that a numerical calculation can be made of the excitation profile of a Raman scattering for a given set of coupling constants and damping factors. Next, the result of an examination is given of the excitation profile of the Raman scatterings of some of the b1g, b2g, and a2g vibrations of nickel octaethylporphyrin and nickel octaethyltetrachloroporphryin. Most of the Raman lines of these nontotally symmetric vibrations show a resonance effect only in the Q-band () region but not in the Soret-band () region. On the basis of this fact, it has been suggested that those Raman lines are caused mainly by the QQ mechanism rather than the QS mechanism. The observed vibrational structure of an excitation profile also seems to support this suggestion. 相似文献
20.
We present a full explanation of the isotope effect in resonant Raman scattering, doping induced, and photo-induced IR-active vibrations of previously reported data in trans-(CH)x, (13CH)x and (CD)x. The interpretation is given in terms of Raman scattering from amplitude modes of the dimerized chains and absorption by charged induced IR-active modes. It is shown that the bare phonon frequencies are properly modified by the isotope mass whereas the observed frequencies are derived by the dressed phonon propagator, and therefore do not follow the usual mass rule. 相似文献