High stimulated Raman spectroscopy

The interacting u and 1/3 bands of natural silane (Lavorel et ah, 1990 Millot et ah, 1990 Lavorel et ah, 1993) and of stannane " SnH4 (Tabyaoui et ah, 1991) have been measured by high resolution infrared and stimulated Raman spectroscopy. All these results were compiled in the T.D.S. data bank (Tomsk-Dijon Spectroscopy project) and were incorporated into a comprehensive model for the rovibrational spectra of methane and other spherical top molecules (Babikov et ah, 1993 Champion et ah, 1992). 

Despite the enormous intensities of stimulated Stokes and anti-Stokes waves, stimulated Raman spectroscopy has been of little use in molecular spectroscopy. The high threshold, which, according to (3.30), depends on the molecular density N, the incident intensity I a and the square of the small polarizability term (daij/dq) in (3.27), limits stimulated emission to only the strongest Raman lines in materials of high densities N. 

E. Esherik, A. Owyoung, High resolution stimulated Raman spectroscopy, iaAdv. Infrared and Raman Spectroscopy, vol. 9 (Heyden, London, 1982)... 

In the first part of this chapter the experimental techniques of linear and nonlinear Raman spectroscopy of gases are reviewed. The nonlinear techniques (Stimulated Raman Gain Spectroscopy, Inverse Raman Spectroscopy, Coherent Anti-Stokes Raman Spectroscopy, Photo-Acoustic Raman Spectroscopy, and Ionization-Detected Stimulated Raman Spectroscopy) have the capability of very high resolution, limited by the linewidths of the lasers used and pressure broadening effects. 

In Europe, spectrometers for high-resolution stimulated Raman spectroscopy have been constructed in Dijon [46,69,83-86] and Madrid [87-93]. As an example. Fig. 8 shows the scheme of the apparatus used in Madrid to obtain stimulated Raman spectra. In this setup, the probe beam was provided by an Ar" laser operating single mode at 488 or 514 nm and frequency stabilized and locked to a hyperfine transition of or... 

P Esherick, A Owyoung. High resolution stimulated Raman spectroscopy. In RJH Clark, RE Hester, eds. Advances in Infrared and Raman Spectroscopy Vol 9. London Heyden, 1982, pp 130— 187. 

H. Berger, B Lavorel, G Millot. High resolution stimulated Raman spectroscopy of gases. In SB Banerjee, SS Jha, eds. Recent Trends in Raman Spectroscopy. Singapore World Scientific, 1989, pp 65-77. 

B Lavorel, G Millot, R Saint-Loup, C Wenger, H Berger, JP Sala, J Bonamy, D Robert. Rotational collisional line broadening at high temperatures in the N2 fundamental Q-branch studied with stimulated Raman spectroscopy. J Phys 47 417-425, 1986. 

J Santos, P Cancio, JL Domenech, J Rodriguez, D Bermejo. Accurate wavenumber measurement in high resolution stimulated Raman spectroscopy (SRS) by using an infrared standard. Fundamental of CH4. Laser Chem 12 53-63, 1992. 

D Bermejo, P Cancio, G DiLonardo, L Fusina. High resolution Raman spectroscopy from vibra-tionally excited states populated by a stimulated Raman process 2 2 — V2 of C2H2 and C2H2-J Chem Phys 108 7224-7228, 1998. 

R Saint-Loup, B Lavorel, G Millot, C Wenger, H Berger. Enhancement of sensitivity in high-resolution stimulated Raman spectroscopy of gases Application to the 21 2 (1285 cm ) Band of CO2. J Raman Spectrosc 21 77-83, 1990. 

RZ Martinez, D Bermejo, J Santos, JP Champion, JC Hilico. High-resolution Raman spectroscopy from vibrationally excited states populated by a stimulated Raman process. 2pi — Pi of CH4. J Chem Phys 107 4864-4874, 1997. 

The Raman spectrum of supersonic jets of CO2 gave a complete characterisation of the system. 46 CARS of CO2 in a freely expanding jet flow shows a band at 1284.73 cm due to ( 02)2- High-resolution stimulated Raman spectroscopy was used to study collisional broadening of vi and 2v2 band components of C02. " High-resolution FTIR studies have been reported for a number of isotopomers of The Raman spectrum of CO2 molecules in a hydrate... 

A technique which combines the high sensitivity of resonant laser ionization methods with the advantages of nonlinear coherent Raman spectroscopy is called IDSRS (ionization detected stimulated Raman spectroscopy). The excitation process, illustrated in Figure 5, can be briefly described as a two-step photoexcitation process followed by ion/electron detection. In the first step two intense narrow-band lasers (ct L, 0) ) are used to vibrationally excite the molecule via the stimulated Raman process. The excited molecules are then selectively ionized in a second step via a two- or multiphoton process. If there are intermediate resonant states involved (as state c in Figure 5), the method is called REMPI (resonance enhanced multi-photon ionization)-detected stimulated Raman spectroscopy. The technique allows an increase in sensitivity of over three orders of magnitude because ions can be detected with much higher sensitivity than photons. 

Kroon R., Baggen M., Lagendijk A. Vibrational dephasing in liquid nitrogen at high densities studied with time-resolved stimulated Raman gain spectroscopy, J. Chem. Phys. 91, 74-8 (1989). 

With the available high-power lasers the nonlinear response of matter to incident radiation can be studied. We will briefly discuss as examples the stimulated Raman effect, which can be used to investigate induced vibrational and rotational Raman spectra in solids, liquids or gases, and the inverse Raman effect which allows rapid analysis of a total Raman spectrum. A review of the applications of these and other nonlinear effects to Raman spectroscopy has been given by Schrotter2i4)... 

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