Cross section collisional

Bonamy L., Bonamy J., Robert D., Temkin S. I. Consequences of angular momenta coupling on generalized spectroscopic relaxation cross-sections collisional narrowing in isotropic and anisotropic Raman CO2 branches, Proc. 13th ICORS. (Wiley Sons, New York) (1992). 

Collisional ionization can play an important role in plasmas, flames and atmospheric and interstellar physics and chemistry. Models of these phenomena depend critically on the accurate detennination of absolute cross sections and rate coefficients. The rate coefficient is the quantity closest to what an experiment actually measures and can be regarded as the cross section averaged over the collision velocity distribution. 

Q-branch non-broadening 117 rotational cross-sections 193 spin-lattice relaxation 47 weak dephasing, collisional narrrowing 93... 

Chatham, H. Hils, D. Robertson, R. Gallagher, A. Total and Partial Electron Collisional Ionization Cross Sections for Methane, Ethane, Silane, and Di silane. J. Chem. Phys. 1984, 81, 1770-1777. 

Other techniques simulate postignition flame processes. In the flow reactor, reactants of interest enter the reactor at one end and travel through a constant temperature region. Ideally, all concentrations and temperatures are consistent across the cross section of the reactor, so that all movement is in one direction and wall reactions are minimized. A similar approach involves the use of crossed molecular beams, ° wherein two molecular beams are directed into one another the area of collisional intersection demonstrates chemistry that can occur in flames. 

The theoretical basis for an effective charge z f[ E) associated with collisional energy loss has been investigated by several authors (see, e.g.. Refs. 69-72). Within the Born approximation, the doubly differential cross section for ejection of an electron with energy IF by a He ion can be written as... 

According to the theoretical investigations by Nakamura [126-128] and Miller [129], the collisional energy dependence of these processes can be calculated if the interaction potential V(R) for the system He(2 S)-M and the autoionization rate r K)jh from the intermediate quasi-molecule [He(2 S)M] to the resulting quasi-molecular ion [HeM] are known. For example, by the classical formula of Miller [129], we have theoretical cross sections for Penning ionization as ... 

A comparison, as shown in Fig. 8, between the experimental results of the collisional energy dependence of the de-excitation cross section of He(2 P) by Ar and the theoretical ones calculated from the W-K theory [140] and the K-W theory [139] makes clearly possible for the first time to compare in detail the experimental results with the theoretical ones [141]. Previous comparisons between experiments and theories have been made only for a value of the rate constant or the cross section, respectively, at a particular temperature of collisional energy, usually at room temperature. The results of temperature-... 

The cross sections show a decrease with increasing collisional energy, which is in marked contrast to the de-excitation cross sections of He(2 S) atoms by the same quenching atoms, as presented in Fig. 6. However, this behavior is rather similar to other quenching molecules, such as CO2 and C2H4, where the cross sections are fairly large, on the order of tens of squared angstroms. 

Table 5 De-excitation Cross Sections (cm) at a Mean Collisional Energy Corresponding to Room Temperature (295 K) and De-excitation Probabilities (P) of Excited Helium Atoms He (He = He(2 S), He(2 S), and He(2 P)) and polarizabilities (am) of target molecules (From Ref. 154.)...

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