Anion excited

Microwave or radio frequencies above 1 MHz that are appHed to a gas under low pressure produce high energy electrons, which can interact with organic substrates in the vapor and soHd state to produce a wide variety of reactive intermediate species cations, anions, excited states, radicals, and ion radicals. These intermediates can combine or react with other substrates to form cross-linked polymer surfaces and cross-linked coatings or films (22,23,29). 

Whereas currently most studies deal with azides, a similar effort devoted to other metal salts such as nitrates and chlorates would be an important step toward understanding electrical initiation of pyrotechnics, and conversely to making possible safe, non-expl igniters. For instance, a study by Maycock (Ref 4) shows that those azides, perchlorates, and nitrates in which the solid state shows absorption on the long wavelength side of the anionic excitation band in soln, are the most unstable members of the respective series. Consequently, there is a direct relationship between the absorption spectra of pyrotechnic oxidizers and their respective sensitivities... 

Electrodes can also play the role of electron acceptor and photogalvanic effects can be induced by anion excitation, eq. 

Two ways are open for the photoinitiation of electron transfer reactions employing anions excitation of the anion itself or the use of anionic quenchers. The next two parts of this review will deal with reactions initiated by these two ways. 

Another H2 production system was constructed using the capacity of fluorescein anion excited state to accept an electron from a reducing agent [166]. Quantum yields were in the range of 0.1 for this system working in absence of an electron relay. 

Figure 4. Anion excitation energies in eV for naphthalene. (ETS) Energies derived from electron transmission measurements in the gas phase (Soln) optical absorption studies in anions in MTHF glass (PPI, Cl) theoretical energies (PT) values derived from the cation spectrum by applications of the Pairing Theorem...

Following the above-mentioned spectroscopic study by Johnson and co-workers [55], Neumark and co-workers [56] explored the ultrafast real-time dynamics that occur after excitation into the CTTS precursor states of I (water) [n — 4-6) by applying a recently developed novel method with ultimate time resolution, i.e., femtosecond photoelectron spectroscopy (FPES). In anion FPES, a size-selected anion is electronically excited with a femtosecond laser pulse (the pump), and a second femtosecond laser pulse (the probe) induces photodetachment of the excess electron, the kinetic energy of which is determined. The time-ordered series of the resultant PE spectra represents the time evolution of the anion excited state projected on to the neutral ground state. In the study of 1 -(water), 263 nm (4.71 eV) and 790 nm (1.57 eV) pulses of 100 fs duration were used as pump and probe pulses, respectively. The pump pulse is resonant with the CTTS bands for all the clusters examined. 

Figure 13. Schematic sketch of a reactive NeNePo control experiment. Control is achieved through two time- and frequency-shifted photodetachment laser pulses employing an anion excited state (M ) for intermediate wavepacket propagation. The wavepacket is finally prepared on the neutral potential energy surface in a region that corresponds to enhanced reactivity of the system. The aim of the experiment and theory is to find optimal composite pulses, based on the concept of the intermediate target outlined in Section III.A, that accomplish such a reactive activation of M . Detection is performed by ionization of the potential reaction products of MO to the cationic state (not shown in the graphic).

If the activator ion is larger than the host-lattice ion which it replaces, e.g. Eu (ionic radius 0.98 A) or Ce (1.07 A) in a Lu host lattice (0.85 A), the environment of the activator will be compelled to expand in order to make room for the activator. If the activator is raised to the excited state, and if this is accompanied by an increase of the equilibrium distance (anion excitation, Ar > 0), then the environment of the activator will have to expand yet further. Since this expansion costs energy, the lattice will tend to oppose the expansion of the luminescent centre, in other words Ar will be relatively small. 

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