Nonreactive scattering

Although the Sclirodinger equation associated witii the A + BC reactive collision has the same fonn as for the nonreactive scattering problem that we considered previously, it cannot he. solved by the coupled-channel expansion used then, as the reagent vibrational basis functions caimot directly describe the product region (for an expansion in a finite number of tenns). So instead we need to use alternative schemes of which there are many. 

Hence, reactions which proceed via complex formation or stripping reactions involving transfer of a relatively massive moiety either are not observed or are registered at grossly distorted intensities. An additional complication is that elastic or nonreactive scattering collisions may allow a primary ion to be detected as a secondary ion. Simple charge transfer... 

Smith, L. L., R. W. Dibble, L. Talbot, R. S. Barlow, and C. D. Carter (1995). Laser Raman scattering measurements of differential molecular diffusion in nonreacting turbulent jets of H2/CO2 mixing with air. Physics of Fluids 7, 1455-1466. 

The products of reactive ion-neutral collisions may be formed in a variety of excited states. Excited products from nonreactive collisions have already been discussed in a previous section. Theoretical calculations of vibrational excitation in the products of symmetric charge-transfer reactions have also been mentioned previously.312-314 The present section deals with excited products from reactive ion-neutral scattering, with special emphasis on luminescence measurements. 

The H3+ molecule ion is the simplest nonlinear molecule, of course, and its potential surface has been calculated in detail and with relatively high accuracy490 (see Figs. 63-65). This ab initio surface, as well as that for Li+-H2,491 have been employed in calculations of cross sections for vibrational excitation in nonreactive scattering collisions492 (see also Section II.B.2.b). An ab initio calculation of the vibrational spectrum of H3+ has also been carried out,207 and it has been suggested that vibrational chemiluminescence should be observable from the reaction H2+ (H2, H)H3+. 

Smith, N. (1986). On the use of action-angle variables for direct solution of classical nonreactive 3D (Di) atom-diatom scattering problems, J. Chem. Phys. 85, 1987-1995. 

Where reaction is possible, the total scattering cross section is made up of reactive and nonreactive contributions. The reaction cross section oR is defined by the expression... 

Ktt(r) outside the centrifugal barrier (see Figure 1,3). By comparing the observed scattering with the distribution calculated on this basis, e can be estimated a rough value of rm can be obtained from data on similar, but nonreactive systems, and aR is typically > 100 A2 and only weakly temperature dependent. 

The dynamics of the interactions that lead to polymer degradation in space are often studied with beam-surface scattering techniques in which the dynamical behavior of gas-phase products (both reactive and nonreactive) is examined. Although infrared emission has been used to detect reaction products, the majority of scattering dynamics studies to date have employed mass spectrometric detection.The most detailed dynamical studies on gas-surface interactions relevant to polymer degradation in space have been done in the laboratory of the authors. ° 36-i4i j.g suits from these studies will be summarized in Secs. 3.3 and 3.4, while the experimental methods follow in this section. 

This bibliography briefly reviews over 700 studies in collision-induced light scattering (CILS) of gases, liquids, and solids. We consider work concerning the spontaneous Raman spectra of transitory, nonreactive complexes of atoms or simple molecules. Much of the literature deals with spectra that are forbidden in the separated molecular partners, but studies of collision-induced spectroscopic components associated with allowed spontaneous... 

C.A. Mead, Superposition of reactive and nonreactive scattering amplitudes in the presence of a conical intersection. J. Chem. Phys., 72 3839-3840, 1980. 

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