Energy of initiation

CONFORMATIONAL ENERGY, PART 1 GEOMETRY AND STERIC ENERGY OF INITIAL CONFORMATION. 

Because the chemiluminescence intensity can be used to monitor the concentration of peroxyl radicals, factors that influence the rate of autooxidation can easily be measured. Included are the rate and activation energy of initiation, rates of chain transfer in cooxidations, the activities of catalysts such as cobalt salts, and the activities of inhibitors (128). 

It must be noted that the above four stages of development are not necessarily well defined in every experiment or accident. For example, in a situation in which the energy of initiation is supplied as a... 

This theory was tested by Yoffe(Ref 1) by comparing the energies required to initiate NG and PETN with and without entrapped air. Samples prepared without air in the form of a continuous Rim requited much higher energies of initiation than samples with entrapped air. A simple method of including a gas phase in an expl is to spread it as a small annulus on a flat anvil. When this is struck with a flat hammer, the small amt of gas in the center is trapped and compressed. In these experiments the size of the annulus was such that the initial vol of the gas was ca 5 x 10"4 cc. A more detailed description of the theory of adiabatic compression and methods of testing are gi ven in Ref 2... 

Fig. 1.2. Intermolecular potential curves and radiative transitions of the complex of molecules 1 and 2. The energy spacing AE = Ef — E-, is the difference of the rotovibrational energies of initial and final states of the complex, , = l7l +EV2j2 and Ef = E VlJl + E V2j2, respectively. The bound and free designate bound and free state energies of the complex a prime indicates final states. Also shown are representative radiative transitions hv from bound state to bound state, and from free state to free state, involving rotovibrational transitions in one or both molecules.

Figure 3. Plot of the laser-induced fluorescence intensity per transition strength vs. energy of initial rotational state in 2U(v" = 0) electronic state. The slope of the line gives the OH rotational temperature (13).

Figure 2.2. The free energy of initial (i) and final (f) terms as a function of generalized classical coordinates. AG0 and 1 are the Gibbs and reorganization energy respectively (the Marcus model).

Using two kinds of supporting frame shown in Fig.3.122, the sample was fixed in the center of the frame, sunk to a specific depth by a crane and initiated. The frame shown in Fig.3.122(a) was used to determine the bubble energy of initiators at a depth of 0.4 m. In the variable initiation test and the variable sample test, in which larger charges were studied, the set-up shown in fig. 3.122(b) was used for a depth of 1.0 m. Thin wire was used to bind the components in place. The atmospheric pressure needed i the calculation was measured at the site every hour. 

Net bubble energy curves are generated by ploting (Net - Eb) vs. the bubble energy of initiators. 

By the described kinetic analysis, the activation energy of initiation [reaction (40)], which is otherwise accessible only with difficulty, could also be estimated. A value about twice that of the activation energy of propagation was found ( 74kJmol-1, or 66 kJ mol-1, Ep = 32.6 kJ mol-1 [16]). 

The change in energy, AE, when the electron falls from n = 6 to n = 1 is AE = energy of final state - energy of initial state... 

Interestingly, because of the factor one half in the first term of eqn 9.30, the estimated overall activation energy of the reaction (ca. 170 kJ mol-1) turns out to be lower than the activation energy of initiation (190 kJ mol-1). Since this factor appears whenever termination is second order in chain carriers, as is true with very few exceptions, and since the activation energies of the propagation steps often are relatively low, such behavior is quite common [19]. 

Table 3.2. Kinetic constants and activation energies of initiation (kjt EJ and of the overall reaction (k, E) in the polymerization of acrylic acid and its sodium salt by H202-ascorbic acid 61)...

Ait = energy of final state - energy of initial state... 

As with anthracene, no delayed excimer fluorescence is observed for 1,2-benzanthracene under these conditions (225), and the deviation of Ps from Vi> may well be due to decay from the relaxed doubly excited singlet pair state as shown in Scheme 5. A relatively smallp = 0.092 value for 1,2-benzanthracene has been estimated from photodimerization results in cyclohexane (229). The 1,2-benzanthracene case illustrates some of the difficulties associated with the evaluation of published TTA data. Undoubtedly, depending upon the availability of quintet, triplet, and excited singlet monomer states at or below the energy of initially formed triplet encounter pairs, exceptions to Eq. 70 and Scheme 5 will be found. The details of the mechanism proposed here may also need to be modified even for anthracene and 1,2-benzanthracene. 

Finally, we will consider problems of dynamics of nanoparticles. The analysis of interaction of nanoparticles among themselves also allows to draw a conclusion on an essential role in this process of energy of initial movement of particles. Various processes at interaction of the nanoparticles, moving with different speed, are observed the processes of agglomerate formation, formation of larger particles at merge of the smaller size particles, absorption by large particles of the smaller ones, and dispersion of particles on separate smaller ones or atoms. 

In the simplest example of a jump mechanism, the species simply migrates to an adjacent vacancy. Whatever the relative energies of initial and final states of the transition, if the states are thermodynamically stable, the process is activated i.e., energy must be supplied to accomplish the transition. The precise route between sites depends on the potential energy surface. 

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