Elastic and inelastic scattering of two molecules

Let us consider the collision between two atoms with masses toa and tob. The center-of-mass coordinate R and center-of-mass velocity V of the two-atom system are given 

M = to a + to b is the total mass of the system and the superscript 0 on the velocities Vi implies the start velocities before the scattering event. The last identity in Eq. (C.l) follows from the fact that the center-of-mass velocity V is constant, since the action forces only depend on the distance between the atoms, making the total force on the system equal to zero. 

X with respect to v°, rotated through an angle rp around v°, and of magnitude fl v° after the scattering event. 

The velocity uA of molecule A with respect to the center-of-mass velocity is given by 

The scattering angle 0 in the laboratory coordinate system is the angle between v and vA, as shown in Fig. C.1.1. We have 

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The relations discussed above can be generalized to elastic, inelastic, and reactive scattering of two molecules for any initial conditions. A detailed discussion of these results is presented in Appendix C. 

In this paper we discuss how neutron scattering spectroscopy can be applied to the study of the structure and dynamics of adsorbed molecules. Since reviews of elastic and inelastic neutron scattering from adsorbed films have recently appeared (1.-3), our purpose here is not to present a comprehensive survey of every adsorbed system investigated by neutron scattering. Rather, we shall be concerned primarily with two questions which are basic to the characterization of adsorbed species on catalysts and which have been central to the discussion of this symposium. These are the extent to which the neutron scattering technique can be used to determine 1) the orientation and position of an adsorbed molecule and 2) the strength and location of the forces bonding a molecule to a surface. 

In order to image the distribution of the solvent, the solution and CO2 and the location of detectable particle formation simultaneously, the setup from the experiments before has to be adapted to other requirements. For this scope, a three-camera system has to be applied as shown in Fig. 24.8. Two cameras are required to detect the inelastic Raman signals, which are scattered from the organic solvents and the CO2 molecules, and therefore indicate the distribution of the solvent and the antisolvent. The third camera is taken to detect the elastic light scattering, which comes from phase boundaries, and therefore indicates the presence of a multiphase flow. The light scattering processes are excited with a pulsed frequency-doubled... 

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