Spectrum resonant photoacoustic

Figure 6.1-28 High resolution photoacoustic Raman (PARS) spectrum of the lower component of the Fermi resonance diad of CO2 at a pressure of 1.6 kPa (11 Torr). Solid line calculated spectrum -1- experimental (Rotger et al., 1992).

The S diads in the vibrational Raman spectrum of CO2 and its isotopic variants were measured and their intensity distribution simulated [48,164-167]. In Fig. 17, a more recent recording of the Raman spectrum of natural CO2 in the Fermi resonance region is presented [53]. The structure of the Q branch of the (10 02) component at 1285 cm has been resolved by CARS [168], stimulated Raman [169], and photoacoustic Raman spectroscopy [106] see Fig. 10. The Q branches of the overtones of the Fermi diad were also observed [170] and the evaluation of their intensities yielded mean polarizability derivatives. In supersonic jet experiments on CO2, the density, condensation, and translational, rotational, and vibrational temperatures were investigated [171]. 

The UV-vis transmittance spectrum shown in Figure 6 contains a Soret band at 406 nm and Q-bands at 510, 538, 580, and 644 nm, the latter being especially characteristic of hemin aggregates as determined by photoacoustic spectroscopy (34) and microspectrophotometry (35). Given the number and energies of iht bands in the absorption spectrum there exist manifold possibilities for resonance Raman enhancement studies. 

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