Effect of rotational excitation

Studies on the effect of rotational excitation in reactants on ion-molecule reaction probability are comparatively scarce. Since some of the excited rotational levels of molecules are usually populated to a considerable extent at ordinary temperatures, it is very difficult to study the reactions of each level individually under normal conditions. The two existing reports, one on the effect of ionic rotational excitation and the other on 

Sbar and Dubrin [241], on the other hand, studied the effect of the rotational energy in the neutral H2 reactant on the cross-section of the reaction 

0 level and more than 99% of the ortho-hydrogen molecules are in the J = 

1 level. Using deuterium as an internal standard, the ratio ArH /ArD was measured in both cases. Careful measurements, including checking for any systematic errors, yielded the ratio 

The above result shows a definite rotational energy dependence of the reaction cross-section, although the effect is very small. This trend is 

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One of the few theoretical papers trying to explain acceleration under the action of microwaves has recently been published by A. Miklavc [18]. He stated that large increases in the rates of chemical reactions occur because of the effects of rotational excitation on collision geometry. This could be cautiously considered when one has knowledge of the quasi-nil energy involved by microwave interaction according to Planck s law [E = hc/X = 0.3 cal/mol]. 

Phosphorescence of s-triazine has been observed by Ohta et al. following excitation of the 6o band of the Si — So transition. Values for the phosphorescence lifetime and quantum yield were reported. The effects of rotational excitation on the yields and decays of the fast and slow components of Si state s-triazine fluorescence have been studied. Excitation along the rotational contours of the 6j and 6o bands revealed that the fast component showed little rotational level dependence in contrast to the slow component. This behaviour was interpreted in terms of an increase in the number of triplet levels coupled to the optically prepared singlet levels with increasing angular momentum quantum number, J. A broad emission feature present in addition to narrowline fluorescence from rovibronic levels of 6 or 6 in S, s-triazine has been observed and the rotational level dependence of its quantum yield and decay over a range of pressures reported... 

An optical parametric oscillator (OPO) was used to select HF(n = 1) in each of the rotational states J = 0—7 in a study of the effect of rotational excitation on the product state distributions in the reaction ... 

STRONG ACCELERATION OF CHEMICAL REACTIONS ARISING THROUGH THE EFFECTS OF ROTATIONAL EXCITATION OF REAGENTS ON COLLISION GEOMETRY... 

Effects of Rotational Excitation on Chemical Reaction Cross-Section... 

Figure 8. The effect of rotational excitation on the distribution of collisions at the barrier for O + H2 reaction, for j = 0 ( ) and for j = 10 (o). The collision energy was 0 = 12 kcal/mol in each case[61].

The largeness of the interval of angle y over which the collisions O + H2 can be reactive is also the reason for the effects of rotational excitation on the distribution of collisions being manifested already at small values of/. The situation in O + HCl (DCl) reactions, to be discussed next, is in this respect entirely different. 

Miklavc. A. (2001) Strong acceleration of chemical reactions occuring throng the effects of rotational excitation on collision geometiy. ChemPhysChem. 8/9, 552-555... 

Similar results obtained for F D2 at 1.82 kcal/mol, as well as F HD product angular distributions and the contour map for DF products at 1.98 kcal/mol are shown in Figures 6, 7, and 8. The effect of rotational excitation was also examined for F H2 by comparing the angular distributions from para and normal hydrogen at... 

Calculations have shown that the faster diffusion rates might be explained by an increase in the factor A with no change in activation energy. Miklavc [39], by analyzing the rotational dependence of the reaction 0 + HC1 0H- -Cl, concluded that marked acceleration may occur as a result of the effects of rotational excitation on collision geometry. 

Several broadly localized sampling patterns, two from the first study and two new ones, were chosen to examine the dynamical effects of rotational excitation. Modes sampled to create the patterns C—Cl and C—HI are illustrated respectively in Figures 3 and 4. The sampling... 

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