CO excitation

It should be considered that, in general, quantum dots are not appropriate FRET acceptors. The broad semiconductor-type absorption bands of QDs typically overlap with the absorption spectra of conventional donors and, therefore, the potential acceptor QD would be always co-excited, see, for example,... 

C12 vs a3 II reactions with oxygen. We observed the same rate constant (within experimental uncertainty) for the reaction of C2 X1and a3 with 02, (See Table I). Many possible channels exist for these reactions, (See Table II). Some of these products have been observed including CO (A1 II) by Filseth et al. (6), CO excited triplets by Wittig (7.) and C20(X3XT) by Donnelly and Pasternack (3). Because of the different reaction pathways that are accessible for C2 X1 2 and a3 H, the observation of identical disappearance rate constants seems to be a coincidence. 

The vibrational state distribution for the ground state CaO product from the reaction Ca + C02 shows a similar monotonic decrease with increasing vibrational quantum number to that from Ca + 02 and, again, only 10% of the reaction energy appears as CaO internal excitation [383]. No information exists about the amount of CO excitation. There is also evidence that low-lying excited states of CaO are produced in the reaction which is again assumed to proceed via an electron-jump mechanism. 

In a few cases, one observes narrow absorption bands caused by the co-excitation of solvent 36) or aqua ligand 85) vibrations. It is worth emphasizing how relatively rare this phenomenon is—again showing a considerable isolation of the individual chromophore. In the case of crystalline solids, the energy band description encounters insurmountable difficulties in the case of fairly localized transitions 50, 53, 57). 

Similar behaviour is observed in both experiments and calculations for HCO H+CO dissociation [88. 89. 90 AND 91] and in calculations for the X —CHW ion-dipole complexes, which participate in Sj 2 nucleophilic substitution reactions [118]. HCO states with HC excitation dissociate more rapidly than do those with CO excitation and, thus, the relative population of HC to CO excitation decreases with time. The unimolecular d5mamics of the X —CH Y complex is similar to that for van der Waals complexes. There is weak coupling between the X —CH Y intermolecular modes and the CH Y intramolecular modes, and the two sets of modes react on different timescales. 

In an experiment attempting to resolve the identity of the CFj, mixtures of C2F4 and NO2 were flash photolyzed in Pyrex (A >300 nm) to avoid dissociating the C2F4, and the CO product was monitored by the CO laser. The CO was found to be vibrationally excited up to n=ll, corresponding to as much as 63 kcal/mole of energy. By analysis of the observed population distribution and consideration of all possible paths and energetics associated with this reaction, it was concluded that CO excited to this extent could come only from the process ... 

Such a mechanism has been proposed by Slanger and observed for the first time by Bondybey et al. in the case of diatomic molecules inbedded in rare-gas matrices. In their subsequent work, similar effects have been found for collisional processes in the gas phase. The vibrational relaxation of CO excited to the v = 3 and c = 2 levels of the A w state induced by collisions with He is more efficient by 4-5 orders of magnitude than in the ground-state CO + He system.Moreover, the form of the fluorescence decay from the o = 1 level observed under v = 2 excitation cannot be fitted if a direct v = 2 v=l relaxation path is assumed the induction time of the relaxed emission being much longer than the decay of the resonance fluorescence. 

In the cases of N2 and CO, which possess large dissociation energies, no dissociation occurs on impact with Ar, but energy transfer from Ar causes extensive electronic excitation. The steady state distributions of energy in both N2 and CO excited by Ar have been investigated in detail. In the case of the most fully allowed transitions observed, little or no rotational (or vibrational) relaxation is expected to occur within the radiative life-time at a pressure of 0 5 torr. In such a case, the observed energy distribution is that initially imparted to the substrate molecule by impact with Ar. In some cases, study of the dependence of rotational energy distribution upon total pressure also enables rates of rotational relaxation to be derived an example is the C n state of N2. ... 

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