Absorption properties of cationic silver cluster–tryptophan complexes: A model for photoabsorption and photoemission enhancement in nanoparticle–biomolecule systems

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• 作者：Rol ; Mitrić ; Jens Petersen ; Alex ; er Kulesza ; Vlasta Bonač ; ić ; -Koutecký ; Thibault Tabarin ; Isabelle Compagnon ; Rodolphe Antoine ; Michel Broyer ; Philippe Dugourd
• 关键词：Cluster ; Cluster– ; biomolecule hybrid ; Absorption spectra ; Excited states ; TDDFT
• 刊名：Chemical Physics
• 出版年：2008
• 出版时间：29 January 2008
• 年：2008
• 卷：343
• 期：2-3
• 页码：372-380
• 全文大小：1129 K

文摘

We present a joint theoretical and experimental study of the size and structure selective absorption properties of cationic silver cluster–tryptophan (l15"">l15&_user=10&_cdi=5230&_rdoc=27&_acct=C000050221&_version=1&_userid=10&md5=e225d0c8958cf8752ac40457fa1211f3"">lt=""Click to view the MathML source"" align=""absbottom"" border=""0"" height=19 width=64>, n = 2–5,9) hybrid systems. Our TDDFT calculations provide insight into the nature of excitations in interacting nanoparticle–biomolecule subunits. The results allowed us to determine characteristic spectral features as fingerprints of two different classes of structures: charge solvated and zwitterionic, which are characterized by different types of charge transfer such as from π-system of tryptophan to silver cluster or from silver cluster to l16"">l16&_user=10&_cdi=5230&_rdoc=27&_acct=C000050221&_version=1&_userid=10&md5=f3ab97260532d12ee553bfae224e3e01"">lt=""Click to view the MathML source"" align=""absbottom"" border=""0"" height=19 width=36> group, respectively. Our MD simulations together with experimentally measured fragmentation channels provide evidence for the structural characterization according to different type of charge transfer, demonstrating the importance of the interplay between theory and experiment. Moreover, the size selectivity seems to be a crucial factor for different photochemical processes. A strong enhancement of absorption has been found theoretically and experimentally for l17"">l17&_user=10&_cdi=5230&_rdoc=27&_acct=C000050221&_version=1&_userid=10&md5=55373fa3ef70a2d4a35f19820234a795"">lt=""Click to view the MathML source"" align=""absbottom"" border=""0"" height=19 width=64>. In contrast, a strong reduction of the photofragmentation yield is observed in l18"">l18&_user=10&_cdi=5230&_rdoc=27&_acct=C000050221&_version=1&_userid=10&md5=ddadd1306a056b5d86a6d7c7e7fcf9e2"">lt=""Click to view the MathML source"" align=""absbottom"" border=""0"" height=20 width=64> in comparison with free l19"">l19&_user=10&_cdi=5230&_rdoc=27&_acct=C000050221&_version=1&_userid=10&md5=4e6ae305be6feabb3c09e8472c493b3c"">lt=""Click to view the MathML source"" align=""absbottom"" border=""0"" height=19 width=30> which may be due to energy dissipation by fluorescence. Thus our findings provide a basis for proposing the structure- and size-dependent mechanism which is responsible for the enhanced absorption and emission in nanoparticle–biomolecular hybrid systems.