Collisions energy

Again, the reaction requires a minimum collision energy Eq, but increases only gradually above the tln-eshold towards a finite, high-energy limit... 

Figure A3.7.5. Velocity-flux contour plot for FIF product from the reaction F + para- i2 HF + F1 at a reactant collision energy of 1.84 kcal mol ...

For a local potential V(r) which supports bound states of angular momentum i and energy < 0, the phase shift linij Q (Ic)) tends in the lunit of zero collision energy to n. When the well becomes deep enough so as to introduce an additional bound level = 0 at zero energy, then linij ... 

Figure B2.2.3. Vibrational relaxation cross sections (quantal and semiclassical) as a fiinction of collision energy E.

Figure B2.3.5. Typical time-of-flight spectra of DF products from the F + D2 reaction [28]- The collision energies and in-plane and out-of-plane laboratory scattered angles are given in each panel. The DF product vibrational quantum number associated with each peak is indicated. Reprinted with pennission from Faiibel etal [28]. Copyright 1997 American Chemical Society.

Faubel M, Martinez-Haya R, Rusin L Y, Tappe U and Toennies J P 1997 Experimental absolute cross sections for the reaction F + D2 at collision energies 90-240 meV J. Phys. Chem. A 101 6415-28... 

Figure B3.4.10. Schematic figure of a ID double-well potential surface. The reaction probabilities exliibit peaks whenever the collision energy matches the energy of the resonances, which are here the quasi-bound states in the well (with their energy indicated). Note that the peaks become wider for the higher energy resonances—the high-energy resonance here is less bound and Teaks more toward the asymptote than do the low-energy ones.

Reactive atomic and molecular encounters at collision energies ranging from thermal to several kiloelectron volts (keV) are, at the fundamental level, described by the dynamics of the participating electrons and nuclei moving under the influence of their mutual interactions. Solutions of the time-dependent Schrodinger equation describe the details of such dynamics. The representation of such solutions provide the pictures that aid our understanding of atomic and molecular processes. 

The hybrid can be used with El, Cl, FI, FD, LSIMS, APCI, ES, and MALDI ionization/inlet systems. The nature of the hybrid leads to high sensitivity in both MS and MS/MS modes, and there is rapid switching between the two. The combination is particularly useful for biochemical and environmental analyses because of its high sensitivity and the ease of obtaining MS/MS structural information from very small amounts of material. The structural information can be controlled by operating the gas cell at high or low collision energies. 

A typical value of the collision number is 10 °s in gases at one atmosphere pressure and room temperature, and the number of successful collisions which can bring about the chemical reaction is equal to this number multiplied by the Anhenius or probability factor, exp(— /f 7 ), where E is the activation energy, the critical collision energy needed for reaction to occur. 

The product of the collision energy E(L) and collision frequency f L) is integrated over all crystals in the distribution to obtain the total rate of energy transfer. Different approaches have been used to estimate E(L) and f L), both for particle impacts and turbulent fluid induced attrition. 

The amount of work performed fixed W. Measurements of mass and velocity of the rubber band tell us, experimentally, the magnitude of (KE),. How do we know (PE)%1 How are we sure that (PE)2 is equal to W and to (KE),1 The evidence we have is that we put an amount of energy into the system and can recover all of it later at will. It is natural to say the energy is stored in the meantime. Then we can say that the rubber band is just like the billiard ball collision energy is conserved at all times. 

Fig. 5.2. Computed percentage error (absolute value) for the He-N2 (j, = 0) system using potential function HFD1. The state to state inelastic cross-sections are compared at several collision energies as a function of A j transitions. The B value for N2 is taken to be about 2 [207],...

Fig. 5.3. Computed average relative energy transfer as a function of collision energy (meV) for the Ar-N2 (jt = 0) and BTT potential in IOS (solid line) and CS (broken line) approximations [208].

Collision energy The energy of the collision between an ion and a gas molecule which may be used to vary the amount of fragmentation observed. 

Figure 1. Time-resolved profiles of cations from the + C2H6 reaction at 2.0-eV collision energy. The decay of CDj and the formation of C2H5 and CD3CH2 cations follow pseudo-first-order kinetics. Reprinted from [38] with permission from Elsevier.

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