Silver excited states

Techniques other than UV-visible spectroscopy have been used in matrix-isolation studies of Ag see, for example, some early ESR studies by Kasai and McLeod 56). The fluorescence spectra of Ag atoms isolated in noble-gas matrices have been recorded (76,147), and found to show large Stokes shifts when optically excited via a Si j — atomic transition which is threefold split in the matrix by spin-orbit and vibronic interactions. The large Stokes shifts may be explained in terms of an excited state silver atom-matrix cage complex in this... 

Photoinduced electron transfer from eosin and ethyl eosin to Fe(CN)g in AOT/heptane-RMs was studied and the Hfe time of the redox products in reverse micellar system was found to increase by about 300-fold compared to conventional photosystem [335]. The authors have presented a kinetic model for overall photochemical process. Kang et al. [336] reported photoinduced electron transfer from (alkoxyphenyl) triphenylporphyrines to water pool in RMs. Sarkar et al. [337] demonstrated the intramolecular excited state proton transfer and dual luminescence behavior of 3-hydroxyflavone in RMs. In combination with chemiluminescence, RMs were employed to determine gold in aqueous solutions of industrial samples containing silver alloy [338, 339]. Xie et al. [340] studied the a-naphthyl acetic acid sensitized room temperature phosphorescence of biacetyl in AOT-RMs. The intensity of phosphorescence was observed to be about 13 times higher than that seen in aqueous SDS micelles. 

For example, the -factor for the normal state of the neutral silver atom, assigned the symbol 4dlbL68 2/S f is observed to be 1.998, and the 0-factors for the first two excited states, 4d105p 2p and 2pf, are observed to be 0.666 and 1.330, respectively the theoretical values for these three states are 2.000, 0.667, and 1.333, so that the agreement is excellent, and one may conclude that the states are correotly assigned. 

For an electron to be transferred from an excited dye molecule to the silver halide conduction band, the excited level should be either above the bottom of the conduction band or near enough to it for thermally assisted transfer to occur during the normal lifetime of the excited state of the dye. If the lowest vacant level of the unexcited dye is below the bottom of the conduction band, transfer of an electron from the conduction band to the unexcited dye molecule becomes possible. This "electron trapping" by the dye could be a factor in the desensitizing action of the dye. 

Therefore, the excited states responsible for the emissions were throughout to be located on the gold and silver atoms in each complex. The theoretical TD-DFT calculations coincided with these results and showed... 

Direct 2PA-induced electron-transfer reactions have also been used to deposit metallic silver wires. In this case, D-jt-D dyes such as 1 (and the other species of Table 11.2) cannot be used as initiators since the ground-state molecule, in addition to the excited state, is capable of reducing Ag+. However, A-D-A dyes such as 43 and 44 (Fig. 11.21), which are much less easily oxidized than 1, have been used to write Ag lines from a resin composed of 2PA dye, thiol-coated Ag nanoparticles, AgBF4, poly(N-vinylcarbazole) and N-ethylcarbazole [133, 174]. Compound 43 has also been used to deposit Au metal [174]. 

Although direct excited-state electron transfer from 2PA dyes to monomer is successful for polymerizing acrylates and depositing silver, few other materials can be patterned in the same way for effective initiation, the reduction potential for the monomer, V2(M/M- ), needs to be greater, i.e. less negative, than the excited-state oxidation potential for the initiator, E /2(M+/M ), which can be estimated from... 

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