Molecule photoselective vibrational

The processes of energy acquisition, storage and disposal in clusters are of considerable interest in their own right and also for the interpretation of similar processes in finite systems. Consider vibrational energy excitation of an intramolecular vibration of a molecule in a cluster, or of a cluster inter-molecular mode(s), which can be accomplished by collisional excitation, photoselective vibrational excitation, electronic excitation followed by intramolecular radiationless transitions or exciton trapping.178 In charged clusters... 

The photoselective laser-induced excitation and dissociation of molecules have been described in detail in a munber of monographs and reviews (Jortner et al. 1981 Letokhov 1983 Bagratashvili et al. 1985f> Letokhov 1989 Quack 1998). Therefore, we shall present below only brief information about the progress made in this field. The main schemes for isotope-selective dissociation of molecules via vibrational states are shown in Fig. 11.1. Accordingly, the problem of photoselective laser control of molecules will be considered below in consecutive order, starting with the simplest scheme of Fig. 11.1(a) and ending with that of Fig. 11.1(c). 

Let the coordinate system be such as that given in Figure 4. IS. The electric vectors of a plane polarized radiation vibrate along OZ in the ZX plane and OX is the direction of propagation of the plane polarized wave. When a solution of anisotropic molecules is exposed to this plane polarized radiation, the electric vector will find the solute molecules in random orientation. Only those molecules absorb with maximum probability which have their transition moment oriented parallel to OZ (photoselection). Those molecules which are oriented by an angle 6 to this direction will have their absorption probability reduced by a factor cos 6, and the intensity of absorption by cos2 6. Finally, the molecules oriented perpendicular to the electric vector will not absorb at all. These statements are direct consequences of directional nature of light absorption... 

Weitz E and Flynn G W1981 Vibrational energy flow in the ground electronic states of polyatomic molecules Advances in Chemical Physics Vol. XLVIl, Photoselective Chemistry part 2, ed J Jortner, R D Levine and S A Rice, pp 185-235... 

We can indeed claim that this is an example of photoselective laser chemistry. The competition between relaxation and reaction of photoex-cited electrons in clusters represented in Fig. 14(b) is reminiscent of the competition in many laser-induced chemical processes, stimulated by the selective absorption of one or more photons, such as photodissociation, photoionization, isomerization, and so forth in polyatomic molecules, where the coupling of many vibrational modes provides energy randomization and relaxation on picosecond time scales. 

The goal of this book is to present in a coherent way the problems of the laser control of matter at the atomic-molecular level, namely, control of the velocity distribution of atoms and molecules (saturation Doppler-free spectroscopy) control of the absolute velocity of atoms (laser cooling) control of the orientation, position, and direction of motion of atoms (laser trapping of atoms, and atom optics) control of the coherent behavior of ultracold (quantum) gases laser-induced photoassociation of cold atoms, photoselective ionization of atoms photoselective multiphoton dissociation of simple and polyatomic molecules (vibrationally or electronically excited) multiphoton photoionization and mass spectrometry of molecules and femtosecond coherent control of the photoionization of atoms and photodissociation of molecules. 

Photoselective laser control of molecules via molecular vibrations... 

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