Charge Transfer Complexation and Excited State Interactions in Porphyrin-Ag NP Structures

1. Charge-Transfer Complexation and Excited-State Interactions in Porphyrin-Silver Nanoparticle Hybrid Structures Sean Murphy, Libai Huang, and Prashant V. Kamat Radiation Laboratory, Department of Chemistry and Biochemistry University of Notre Dame, Notre Dame, Indiana 46556, United States Reprinted with permission from {J. Phys. Chem. C, 2011, 115 (46) pp 22761 - 22769}. Copyright {2011} American Chemical Society

2. Background • Metallic nanoparticles possess localized surface plasmon resonance producing a large electromagnetic field near the surface of the nanoparticle. • Light-induced interaction between metallic nanoparticles and photoactive molecules has been the subject of many recent studies. • Adsorption of the dye and electron transfer produce modulated optical properties for dye-metal nanoparticle composites. Reprinted with permission from {J. Phys. Chem. C, 2011, 115 (46) pp 22761 - 22769}. Copyright {2011} American Chemical Society

3. Absorption Properties Red-shifted absorption band observed for the TAPP· · ·Ag nanoparticle complex. Reprinted with permission from {J. Phys. Chem. C, 2011, 115 (46) pp 22761 - 22769}. Copyright {2011} American Chemical Society

4. Surface Enhanced Resonance Raman (SERRS) and Chemical Enhancement A greater SERRS signal for TAPP than for two other free-base pophyrins with different phenyl-substituents along with selective enhancement for TAPP Raman bands suggests chemical enhancement. Reprinted with permission from {J. Phys. Chem. C, 2011, 115 (46) pp 22761 - 22769}. Copyright {2011} American Chemical Society

5. Excited State Interaction The transient absorption spectrum of neat TAPP exhibits little change within a 40 ps time window. For TAPP· · ·Ag nanoparticle complex we observe the formation of a transient bleach centered near 566 nm. Reprinted with permission from {J. Phys. Chem. C, 2011, 115 (46) pp 22761 - 22769}. Copyright {2011} American Chemical Society

6. Fast Charge Separation and Slower Recombination Fast quenching of TAPP fluorescence for the TAPP· · ·Ag nanoparticle complex indicates charge separation. Charge recombination leads to bleaching recovery. Reprinted with permission from {J. Phys. Chem. C, 2011, 115 (46) pp 22761 - 22769}. Copyright {2011} American Chemical Society

7. Summary • Amine functional groups of TAPP lead to CT complexation with Ag nanoparticles. • CT complexation leads to observation of a red- shifted absorption band and chemical enhancement of the SERRS signal. • Fast charge separation and subsequent recombination are confirmed by femtosecond time-resolved spectroscopies. Reprinted with permission from {J. Phys. Chem. C, 2011, 115 (46) pp 22761 - 22769}. Copyright {2011} American Chemical Society

8. Thank you for viewing the slideshow! This work can be found in the Journal of Physical Chemistry C (DOI: 10.1021/jp205711x) J. Phys. Chem. C, 2011, 115 (46) pp 22761 - 22769 Additional information about the Kamat research group can be found at www.nd.edu/~pkamat Additional information about the Huang research group can be found at http://www.nd.edu/~lhuang2/Libai_Huang/Home.html

Charge Transfer Complexation and Excited State Interactions in Porphyrin-Ag NP Structures

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Charge Transfer Complexation and Excited State Interactions in Porphyrin-Ag NP Structures