Kinetics and Low Temperature Studies of Electron Transfers in Films of Small (<2 nm) Au Monolayer Protected Clusters

Autor:	Tessa M. Carducci, Royce W. Murray
Rok vydání:	2013
Předmět:	Electron transfer Work (thermodynamics) Colloid and Surface Chemistry Chemistry Chemical physics Kinetics Dispersity Monolayer General Chemistry Electron Atomic physics Biochemistry Catalysis
Zdroj:	Journal of the American Chemical Society. 135:11351-11356
ISSN:	1520-5126 0002-7863
Popis:	This work examines the temperature dependence of electron transfer (ET) kinetics in solid-state films of mixed-valent states of monodisperse, small (2 nm) Au monolayer protected clusters (MPCs). The mixed valent MPC films, coated on interdigitated array electrodes, are Au25(SR)18(0/1-), Au25(SR)18(1+/0), and Au144(SR)60(1+/0), where SR = hexanethiolate for Au144 and phenylethanethiolate for Au25. Near room temperature and for ca. 1:1 mol:mol mixed valencies, the bimolecular ET rate constants (assuming a cubic lattice model) are ~2 × 10(6) M(-1) s(-1) for Au25(SR)18(0/1-), ~3 × 10(5) M(-1) s(-1) for Au25(SR)18(1+/0), and ~1 × 10(8) M(-1) s(-1) for Au144(SR)60(1+/0). Their activation energy ET barriers are 0.38, 0.34, and 0.17 eV, respectively. At lowered temperatures (down to ca. 77 K), the thermally activated (Arrhenius) ET process dissipates revealing a tunneling mechanism in which the ET rates are independent of temperature but, among the different MPCs, fall in the same order of ET rate: Au144(+1/0)Au25(0/1-)Au25(1+/0).
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_dedup___::73e606f58b2d40c65423d0b7f791ecef https://doi.org/10.1021/ja405342r Zobrazit plný text záznamu