Design and construction of a far-infrared free-electron laser driven by a microtron

Lee, Jongmin; Lee, Byung Cheol; Jeong, Young Uk; Cho, Sung Oh; Kim, Sun Kook; Heon, Byung; Kazakevich, Gregory; Miginsky, Sergei V.; Vovly, Pavel; Кулипанов, Г.Н.

doi:10.1016/s0168-9002(97)01387-9

Cited by 9 publications

(7 citation statements)

References 2 publications

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“…This value is very similar to the value previously determined for the benzyl methyl viologen radical cation BMVc + (log K Dim ¼ 3.46(5)), 30 but much higher than that reported for the methyl viologen radical cation MVc + (log K Dim $2.5-2.9). 69,70 The values of K Dim are also similar to those measured for viologens decorated with hydrophobic alkyl substituents. 15 This suggested that increasing the hydrophobicity around the BIPYc + unit with aryl/alkyl substituents favors the intermolecular pimerization in aqueous solution.…”

Section: Characterization Of the Radical Cationssupporting

confidence: 70%

Viologen–cucurbituril host/guest chemistry – redox control of dimerization versus inclusion

et al. 2021

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Section: Characterization Of the Radical Cationssupporting

confidence: 70%

Viologen–cucurbituril host/guest chemistry – redox control of dimerization versus inclusion

et al. 2021

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“…For A 21 42+ , 1) only about 9 out of 21 viologen units can be chemically reduced under conditions in which 21 A 1 2+ species are fully reduced, and 2) several one‐electron‐reduced viologens of the dendrimer associate to give dimers in common with other polyviologen species 5. 9, 19, 21, 22 Once again, we can conclude that only a fraction of the viologen units contained in the dendrimers can be reduced.…”

Section: Resultsmentioning

confidence: 66%

“…This spectrum is much less intense than that obtained upon reduction of A 1 2+ (Figure 5a) and shows the spectral features for both monomeric (band with maxima at 396 and 607 nm) and dimeric19 (bands with maxima at 355, 537, and 850 nm) monoreduced viologens. Since each dendrimer contains different types of viologen units, and, upon one‐electron reduction, such units can presumably give rise to different dimers,21 a complete deconvolution of the spectrum of Figure 5b into its components is impossible. Nevertheless, some interesting pieces of information can be drawn from the spectrum.…”

Section: Resultsmentioning

confidence: 99%

Complete Charge Pooling is Prevented in Viologen‐Based Dendrimers by Self‐Protection

Marchioni

Venturi

Ceroni

et al. 2004

Chemistry A European J

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We have investigated the electrochemical behavior, and chemical and photosensitized reduction of two dendrimers based on a 1,3,5-trisubstituted benzenoid core, which contain 9 and 21 4,4'-bipyridinium (usually called viologen) units, respectively, in their branches and are terminated with tetraarylmethane groups. For comparison purposes, the behavior of reference compounds that contain a single viologen unit have also been investigated. We have found that only part of the viologen units can be reduced in the dendrimer species. For the larger dendrimer, the number of reducible viologens (out of the 21 present) is 14 in electrochemical experiments (in MeCN), 9 on reduction with bis(benzene)chromium (in MeCN), and 13 by photoinduced electron transfer with 9-methylanthracene as a photosensitizer and triethanolamine as a sacrificial reductant in CH2Cl2. The reduced viologen units undergo partial dimerization. The photochemical experiments have shown that only monomeric, one-electron-reduced viologen units are formed at the beginning of the irradiation, followed by dimer formation, until a photostationary state is reached that contains 40 % nonreduced, 33 % monomeric reduced, and 27 % reduced units associated in the dimeric form. The results suggest that, upon reduction of a fraction of the viologen units, the dendrimer structure shrinks, with the result that the bulky terminal groups protect other viologen units from being reduced.

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“…The self-assembly and redox-functionality of viologens on solid electrodes (Au, Ag, Pt, HOPG, etc.) have been widely investigated by cyclic voltammetry, UV-vis-absorption, [42][43][44][45] vibrational spectroscopy (IR and Raman), 13,[31][32][33][34][35][36][37][42][43][44][45][46][47][48][49][50][51][52] quartz crystal microbalance, [21][22][23]53,54 electroreflectance, [24][25][26][27][28][29][30] STM, 14 and STS. 13 The solution-based electrochemical studies provide important clues for understanding the properties of surfaceimmobilized viologen monolayers.…”

Section: Introductionmentioning

confidence: 99%

Potential-Induced Redox Switching in Viologen Self-Assembled Monolayers: An ATR−SEIRAS Approach

Han¹,

Li²,

Wandlowski³

et al. 2007

J. Phys. Chem. C

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Monolayers of viologens (N-alkyl-N′-(n-thioalkyl)-4,4′-bipyridinium bromide, n ) 6, 8, 10) have been selfassembled from ethanolic solution onto gold substrates. Their structure and redox functionality were studied by cyclic voltammetry and in situ ATR-SEIRAS. Voltammetric experiments revealed that the first redox process, V 2+ T V •+ , is reversible, whereas the second redox process, V •+ T V 0 , is quasi reversible. The V 2+ adlayer exhibits a sandwich-like structure. Van der Waals interactions between the alkyl chains lead to two well-ordered hydrophobic layers, with the redox-active bipyridinium unit enclosed in between. The alkyl chains are aligned in an all-trans configuration in a tilted orientation with respect to the surface normal and exhibit a slight conformational disorder. The long axis of the central bipyridinium rings is also tilted. The alignment of V 2+ is stabilized by interplanar π-π stacking and electrostatic coulomb interactions. Both monomers and dimers of V •+ coexist in the V •+ adlayer. The molecular alignment of the V •+ adlayer is stabilized by the strong vibronic coupling within the dimers and the π-π stacking between the monomers. Increasing length of the alkyl chain results in more tilted bipyridinium units, and favors both the dimerization and the alignment of V •+ within the SAMs. The complex reaction, V 2+ f V •+ , is described as electron transport from the electrode to the V 2+ moiety followed by the dimerization of V •+ , the delocalization of the radical electrons, and the migration of coadsorbed ClO 4anions.

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Design and construction of a far-infrared free-electron laser driven by a microtron

Cited by 9 publications

References 2 publications

Viologen–cucurbituril host/guest chemistry – redox control of dimerization versus inclusion

Viologen–cucurbituril host/guest chemistry – redox control of dimerization versus inclusion

Complete Charge Pooling is Prevented in Viologen‐Based Dendrimers by Self‐Protection

Potential-Induced Redox Switching in Viologen Self-Assembled Monolayers: An ATR−SEIRAS Approach

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