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Petek ES, Katsumata R. Thickness Dependence of Contact Angles in Multilayered Ultrathin Polymer Films. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c01123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Evon S. Petek
- Department of Polymer Science and Engineering, University of Massachusetts Amherst, 120 Governors Dr, Amherst, Massachusetts 01003, United States
| | - Reika Katsumata
- Department of Polymer Science and Engineering, University of Massachusetts Amherst, 120 Governors Dr, Amherst, Massachusetts 01003, United States
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Abstract
We have studied optical properties of single-layer and multi-fold nanoporous gold leaf (NPGL) metamaterials and observed highly unusual transmission spectra composed of two well-resolved peaks. We explain this phenomenon in terms of a surface plasmon absorption band positioned on the top of a broader transmission band, the latter being characteristic of both homogeneous "solid" and inhomogeneous "diluted" Au films. The transmission spectra of NPGL metamaterials were shown to be controlled by external dielectric environments, e.g. water and applied voltage in an electrochemical cell. This paves the road to numerous functionalities of the studied tunable and active metamaterials, including control of spontaneous emission, energy transfer and many others.
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Lee KJ, Beyreuther E, Jalil SA, Kim SJ, Eng LM, Guo C, André P. Optical-field driven charge-transfer modulations near composite nanostructures. Nat Commun 2020; 11:6150. [PMID: 33262344 PMCID: PMC7708636 DOI: 10.1038/s41467-020-19423-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 10/13/2020] [Indexed: 11/09/2022] Open
Abstract
Optical activation of material properties illustrates the potentials held by tuning light-matter interactions with impacts ranging from basic science to technological applications. Here, we demonstrate for the first time that composite nanostructures providing nonlocal environments can be engineered to optically trigger photoinduced charge-transfer-dynamic modulations in the solid state. The nanostructures explored herein lead to out-of-phase behavior between charge separation and recombination dynamics, along with linear charge-transfer-dynamic variations with the optical-field intensity. Using transient absorption spectroscopy, up to 270% increase in charge separation rate is obtained in organic semiconductor thin films. We provide evidence that composite nanostructures allow for surface photovoltages to be created, which kinetics vary with the composite architecture and last beyond optical pulse temporal characteristics. Furthermore, by generalizing Marcus theory framework, we explain why charge-transfer-dynamic modulations can only be unveiled when optic-field effects are enhanced by nonlocal image-dipole interactions. Our demonstration, that composite nanostructures can be designed to take advantage of optical fields for tuneable charge-transfer-dynamic remote actuators, opens the path for their use in practical applications ranging from photochemistry to optoelectronics. Controlling and modulating charge transfer dynamics in composite nanostructures, though promising for optoelectronic applications, remains a challenge. Here, the authors report optical control of charge separation and recombination processes in organic semiconductor-based composite nanostructures.
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Affiliation(s)
- Kwang Jin Lee
- The Institute of Optics, University of Rochester, Rochester, New York, USA. .,Department of Physics, Ewha Womans University, Seoul, South Korea. .,CNRS-Ewha International Research Center, Ewha Womans University, Seoul, South Korea.
| | - Elke Beyreuther
- Institut für Angewandte Physik, Technische Universität Dresden, Dresden, Germany
| | - Sohail A Jalil
- The Institute of Optics, University of Rochester, Rochester, New York, USA.,Changchun Institute of Optics, Fine Mechanics, and Physics, Changchun, China
| | | | - Lukas M Eng
- Institut für Angewandte Physik, Technische Universität Dresden, Dresden, Germany
| | - Chunlei Guo
- The Institute of Optics, University of Rochester, Rochester, New York, USA.
| | - Pascal André
- CNRS-Ewha International Research Center, Ewha Womans University, Seoul, South Korea. .,Laboratoire des Multimatériaux et Interfaces, Université Claude Bernard Lyon 1, UMR CNRS 5615, Villeurbanne, France. .,RIKEN, Wako, Japan.
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Effect of Random Nanostructured Metallic Environments on Spontaneous Emission of HITC Dye. NANOMATERIALS 2020; 10:nano10112135. [PMID: 33120972 PMCID: PMC7694070 DOI: 10.3390/nano10112135] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 10/11/2020] [Accepted: 10/16/2020] [Indexed: 11/18/2022]
Abstract
We have studied emission kinetics of HITC laser dye on top of glass, smooth Au films, and randomly structured porous Au nanofoams. The observed concentration quenching of luminescence of highly concentrated dye on top of glass (energy transfer to acceptors) and the inhibition of the concentration quenching in vicinity of smooth Au films were in accord with our recent findings. Intriguingly, the emission kinetics recorded in different local spots of the Au nanofoam samples had a spread of the decay rates, which was large at low dye concentrations and became narrower with increase of the dye concentration. We infer that in different subvolumes of Au nanofoams, HITC molecules are coupled to the nanofoams weaker or stronger. The inhibition of the concentration quenching in Au nanofoams was stronger than on top of smooth Au films. This was true for all weakly and strongly coupled subvolumes contributing to the spread of the emission kinetics. The experimental observations were explained using theoretical model accounting for change in the Förster radius caused by the strong energy transfer to metal.
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