Raman schematic representation

Figure Bl.2.2. Schematic representation of the polarizability of a diatomic molecule as a fimction of vibrational coordinate. Because the polarizability changes during vibration, Raman scatter will occur in addition to Rayleigh scattering.

Figure 2.52 Schematic representation of the transitions giving rise to the Raman effect. GS = ground electronic state, ES = excited electronic state, VS = virtual electronic stale, R = Rayleigh scattering, S = transitions giving rise to Stokes lines, AS = transitions giving rise to Anti-Stokes lines, RRS = transitions giving rise to resonance Raman.

Fig. 3. Schematic representation of the Raman spectra of the cyclic molecules Sg, S, Sg, Sg, Sjg and Sj2, For each compound characteristic strong lines can be found which allow its detection in mixtures...

For our purpose, it is convenient to classify the measurements according to the format of the data produced. Sensors provide scalar valued quantities of the bulk fluid i. e. density p(t), refractive index n(t), viscosity dielectric constant e(t) and speed of sound Vj(t). Spectrometers provide vector valued quantities of the bulk fluid. Good examples include absorption spectra A t) associated with (1) far-, mid- and near-infrared FIR, MIR, NIR, (2) ultraviolet and visible UV-VIS, (3) nuclear magnetic resonance NMR, (4) electron paramagnetic resonance EPR, (5) vibrational circular dichroism VCD and (6) electronic circular dichroism ECD. Vector valued quantities are also obtained from fluorescence I t) and the Raman effect /(t). Some spectrometers produce matrix valued quantities M(t) of the bulk fluid. Here 2D-NMR spectra, 2D-EPR and 2D-flourescence spectra are noteworthy. A schematic representation of a very general experimental configuration is shown in Figure 4.1 where r is the recycle time for the system. 

Figure 3.8 Schematic representation of the Raman vibrations for cyclic sulfur allotropes. Reproduced from Figure 3 in R. Steudel, Top. Curr. Chem., 1982, 102, 149, with permission Springer Science.

Fig. 3.20 Schematic representation of infrared and Raman experiments. In infrared... 

Figure 3.5. Schematic representation of Raman spectra of alkyl cations.

Fig. 2.1. Schematic representations of the confocal type Raman probe (A) and the miniaturized Raman probe (B)...

M in concentration. This is in the range required for single-molecule detection. These sensitivity levels have been obtained on colloidal clusters at near-infrared excitation. Figure 10.3 is a schematic representation of a single-molecule experiment performed in a gold or silver colloidal solution. The analyte is provided as a solution at concentrations smaller than 10-11 M, Table 10.1 lists the anti-Stokes/Stokes intensity ratios for crystal violet (CY) at 1174 cm-1 using 830-nm near-infrared radiation well away from the resonance absorption of CY with a power of 106 W/cm2 [34]. CV is attached to various colloidal clusters as indicated in the table. Raman cross sections of 10-16 cm2/molecule or an enhancement factor of 1014 can be inferred from the data. 

FIGURE 4.19 Schematic representation of a conventional Raman spectrometer. 

Figure 3-43 Schematic representation of the photoacoustic Raman scattering (PARS) process, (a) A simple energy level diagram illustrating the Raman interaction that occurs in the PARS process, (b) Basic elements of the PARS experimental arrangement. The pump beam is attenuated and the Stokes beam is amplified by the stimulated Raman process that takes place where the beams overlap in the gas sample cell. For each Stokes photon created by the Raman process, one molecule is transferred from the lower state to the upper state of the transition. Collisional relaxation of these excited molecules produces a pressure change that is detected by a microphone. (Reproduced with permission from Ref. 107.)...

Figure 1 Schematic representation of a time-resolved coherent Raman experiment, (a) The excitation of the vibrational level is accomplished by a two-photon process the laser (L) and Stokes (S) photons are represented by vertical arrows. The wave vectors of the two pump fields determine the wave vector of the coherent excitation, kv. (b) At a later time the coherent probing process involving again two photons takes place the probe pulse and the anti-Stokes scattering are denoted by subscripts P and A, respectively. The scattering signal emitted under phase-matching conditions is a measure of the coherent excitation at the probing time, (c) Four-photon interaction scheme for the generation of coherent anti-Stokes Raman scattering of the vibrational transition.

Figure 4.8-4 Raman spectra of trans-poly(acetylene) excited by different laser lines, according to (Itnhoff, 1983) (a), and a schematic representation of the dispersion effect in conjugated polymers. The continuous and the dashed arrows, respectively, refer to a red and a blue laser (b).

Figure 6.1-3 Schematic representation of continuum resonance Raman scattering for the Br2 molecule. The incident laser frequency (o o) is in resonance with the continuous states of the repulsive 77 excited state and the repulsive part of the bound B(- 77o-i- ) state, which is above the dissociation limit at around 20 000 cm (Baierl and Kiefer, 1981).

Figure 4 Schematic representation of the normal vibrational modes of the CO2 molecnle (Adapted from Cotton ). The molecnlar schematics show the atomic displacements that occur during each normal mode. The partial charges shown indicate the bond dipoles, and the elhpsoids represent the molecular polarizabihties. Note that only v results in a change in polarizabihty but no change in molecular dipole moment (thus is Raman active), while i>2 and V3 result in changes in molecular dipole moment but not polarizability (thus are IR active)...

Fig. 3.30 Schematic representation of infrared and Raman experiments. In infrared spectroscopy the excitations are detected by absorption of characteristic frequencies, in Raman spectroscopy the excitations are detected by characteristic s/ti/is in frequencies of the scattered light, [rrom Harris, D. C Bertolucci, M. D. Symmetry and Spectroscopy, Dover New York, 1989. Reproduced with permission.]...

Fig. 8.3 Schematic representation of the confocal Raman microscope inclusive light path...

Fig.1 A schematic representation of process in double-resonant Raman scattering [6]...

Fig. 1 Schematic representation of the Raman spectra of some sulfur allotropes consisting of homocycles (fundamental modes given only after [80])...

In Raman spectroscopy (cf., e.g., [183-187]), the strayUght spectrum is recorded of a sample which is irradiated with monochromatic light (produced, e.g.,by a laser). A schematic representation of the Raman scattering experiment is shown in Fig. 10. 

Fig.10. Schematic representation of the Raman scattering experiment (adopted from [186])...

Fig. 5.3 Vibrational modes of the (Raman active) phonons Ag and Bg, schematic representation, b is the twofold axis of the monoclinic crystal. For the Bg phonons the axes of rotational symmetry of the two molecules in the unit cell are parallel, while for the Ag phonons, they are oriented antiparallel. K=0.

The origin of the Raman spectmm is markedly different to that of the IR spectrum. The Raman effect arises from the inelastic scattering of a monochromatic light source, usually a laser with a wavelength of between 200 and 1400nm (ultraviolet, visible or near-IR). Figure 6.1 shows a schematic representation of the Raman effect. As the incident photons of the laser beam interact with the... 

Fig. 4.13 Schematic representation of the optical set-up (a) and hemispherical cell (b) forTIR Raman microspectroscopy. TIR Raman spectra of Mn(TMPyP) at the toluene/water interface with two different concentrations of dihexadecyl phosphate (DHP) in the organic phase are shown in (c). The band at 394 cm" corresponds to the symmetric breathing mode of the porphyrin ring. The spectral features were normalized by the toluene band at 520 cm . The spectra were collected with s-polarization. Reprintedwith permission from Ref [33]. Copyright (2003)...

Figure 8.3 Schematic representation of two eletronic states (ground and excited) and their respective vibrational levels (the eletronic and vibrational levels are not represented on the same scale). The arrows Indicate the types of transitions that can occur among the different levels. It Is Important to say that in the case of Raman scattering, if the laser line (XJ used has energy similar to one electronic transition of the molecule, the signal can be intensified by a resonance process, know as the resonance Raman effect. In the figure, and laser line and scattering frequencies, respectively (just the Stokes, Vs < Vg, component is shown in the diagram)...

The test equipment of crystal type of gas hydrates consists of a laser Raman spectrometer, gas supply system, jacketed cooling type high-pressure visual cell, temperature control system, data acquisition and other parts. The experiment using a laser Raman spectrometer for the JY Co. in French produced Lab RAM HR-800 type visible confocal Raman microscope spectrometer. Laboratory independently designed a cooled jacket visible in situ high-pressure reactor, reactor with sapphire window to ensure full transparency of laser, and high pressure performance, visual reactor effective volume 3 ml, compression 20 MPa effective volume, to achieve characteristics of gas hydrate non-destructive and accurate measurement. The schematic representation of equipment is shown in Eigure 1. 

Fig. 7. Schematic representation of the electronic Raman scattering process in an intermediate-valence Eu compound showing an interconfigura-tional excitation energy , 0. Indicated are the in/raconflgurational energy losses ( L,imra) snd the interconflgurational energy losses ( l,inter =...

Figure 29 Schematic representation of the experimental assembly for in situ Raman microspectrometry studies of guest exchange in a urea inclusion compound, comprising the single crystal of the urea inclusion compound (green), initially containing 1,8-dibromooctane guest molecules, attached to a reservoir containing liquid pentadecane (blue).

Fig. 8 (Colour online) Raman spectra of pristine graphene (spectrum 1) and graphane (spectrum 2) deposited on a substrate (a) and suspended (b). The D peak is activated by the binding event. Its intensity increases for increasing hydrogen content. The reaction with hydrogen is reversible, so that the D peak almost disappears after annealing of the sample (spectrum 3). c) Schematic representation of the crystal structure of graphene and d) theoretically predicted graphane. Adapted from Ref. 74.

Fig. 14 Schematic representation of the SOFC rig developed by Rob Walker s group. This setup allows for combined Raman spectroscopy and electrochemical characterisation of operational SOFCs. Figure reproduced from [147],... 

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