Ionization detected stimulated Raman spectroscopy IDSRS

Figure 3.6-5 Energy-level diagram illustrating the two excitation steps of Ionization Detected Stimulated Raman Spectroscopy (IDSRS).

S Ionization detected stimulated Raman spectroscopy (IDSRS)... 

Fig. 7 Raman gain = stimulated Raman gain spectroscopy (SRGS), inverse Raman = inverse Raman spectroscopy (IRS) or stimulated Raman loss spectroscopy (SRLS), coherent anti-Stokes Raman spectroscopy (CARS), photoacoustic Raman spectroscopy (PARS), or ionization-detected stimulated Raman spectroscopy (IDSRS). In the following sections, the various methods are briefly described. More detailed information can be found in books [59-61], reviews [45,46,57,58,62,63] and conference reports [64-73].

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. 

From the sophisticated measurements performed in Felker s laboratory it seems that the various versions of ionization-detected. stimulated Raman techniques (with mass analysis) have great capabilities in the high resolution vibrational spectroscopy of weakly bound complexes and clusters. One expects that IDSRS will become increasingly productive in the studies of cluster ground-state structure and dynamics. 

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