Anti-Stokes Raman spectrum

Anti-Stokes picosecond TR spectra were also obtained with pump-probe time delays over the 0 to 10 ps range and selected spectra are shown in Figure 3.33. The anti-Stokes Raman spectrum at Ops indicates that hot, unrelaxed, species are produced. The approximately 1521 cm ethylenic stretch Raman band vibrational frequency also suggests that most of the Ops anti-Stokes TR spectrum is mostly due to the J intermediate. The 1521 cm Raman band s intensity and its bandwidth decrease with a decay time of about 2.5 ps, and this can be attributed the vibrational cooling and conformational relaxation of the chromophore as the J intermediate relaxes to produce the K intermediate.This very fast relaxation of the initially hot J intermediate is believed to be due to strong coupling between the chromophore the protein bath that can enable better energy transfer compared to typical solute-solvent interactions. ... 

Fig. 1. Stokes and anti-Stokes Raman spectrum of carbon tetrachloride...

Figure 10.3. Schematic experimental set-up for single-molecule SERS. Insert (top) shows a typical Stokes and anti-Stokes Raman spectrum. Insert (bottom) shows an electron microscope image of SERS-active colloidal clusters. (With permission from Ref. 21.)...

Figure 5.9a shows a resonance anti-Stokes Raman spectrum of UV-irradiated SWNTs measured by using quasi-monochromatic excitation with the narrowband 790-mn beam (1.57 eV), containing information about the electron-phonon coupling in frequency domain. The characteristic Raman bands, G- and D-bands, were clearly observed. The relatively large D-band indicates the introduction of defects... 

Fig. 5.9 (a) Anti-Stokes Raman spectrum of SWNTs excited by the 790-nm narrowband pulses, (b) Time-frequency 2D-CARS spectra of the SWNTs. (c) Time-resolved CARS spectrum of SWNTs at 0.84 ps [32]... 

Figure 4.4. The Stokes and anti-Stokes Raman spectrum of sulphur at 1064 nm laser excitation. The feature between 9300 and 9394 cm is an experimental artefact due to the optical filter used to suppress the very intense Rayleigh band.

Figure 14 Simultaneous measurement of both the Stokes and anti-Stokes Raman spectrum of a 1 ym anatase (Ti02) film using the equipment diagrammed in Figure 5.

Figure 33 Anti-Stokes Raman spectrum of DLC films observed under the 1236-A excitation [73]. (Reproduced from Journal of Non-Crystalline Solids, 227-230, Ivanov-Omskii, V. I., et al.. Bonded and non-bonded hydrogen in diamond-like carbon, pp. 627-630. Copyright 1998, with permission from Elsevier-Science.)...

Fig. 0.4. Experimental nitrogen Q-branch of coherent anti-Stokes Raman scattering spectrum (CARS) measured at 700 K and different pressures [14].

Figure 7.2 Complete Raman spectrum of carbon tetrachloride, illustrating the Stokes Raman portion (on left, negative shifts), Rayleigh scattering (center, 0 shift), and the anti-Stokes Raman portion (on right, positive shifts). Reprinted from Nakamoto (1997) [7] and used by permission of John Wiley Sons, Ltd., Chichester, UK.

Vartiainen, E. M. 1992. Phase retrieval approach for coherent anti-Stokes Raman scattering spectrum analysis. J. Opt. Soc. Am. B 9 1209-14. 

Here Uab is the Raman transition moment, fic is the infrared transition moment, g and V refer to ground and excited vibrational states, coir is the input infrared frequency, coq is the resonance frequency of the adsorbate, and T is a damping factor [8, 14—17]. Thus, the SFG intensity is related to the product of an (anti Stokes) Raman transition and an infrared transition. The SFG intensity is enhanced when the input infrared wavelength coincides with a vibrational mode of the adsorbate and the result of an SFG spectrum corresponds to the vibrational levels of the molecule. This situation is shown schematically in Fig. 5.1. From (5), non-zero SFG intensity will occur only for transitions that are both Raman and IR allowed. This situation occurs only for molecules lacking inversion symmetry [19]. 

OPUS differentiates between the Raman spectrum and the single channel spectrum. The single channel spectrum of the Stokes and anti-Stokes Raman scattering for a sulphur sample is shown in Fig. 4.4. Note that the abscissa here is expressed in absolute wavenumbers. Therefore, the exciting laser line appears at vl = 9394 cm and the bands at wavenumbers lower and higher than 9394 cm arise from Stokes and anti-Stokes Raman scattering, respectively. On the other hand, a standard Raman spectrum comprises the spectral range from 0 to 3500 cm. Load the file RAMAN SULPHUR and find out the difference between these two types of spectra. 

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