Florencio Eloy Hernández
Plasmonics and Materials Design

(Full Image)

Professor of Chemistry and Optics Ph.D., Universidad Central de Venezuela Phone: 407-823-0843 E-mail: florenzi@mail.ucf.edu Webpage: chemistry.cos.ucf.edu/florenzi View Full Curriculum Vita

Recent Accomplishments

• 2005-2006 Teaching Incentive Program (TIP) Award presented by UCF
• 2004-American Chemical Society (Orlando Section) Outstanding Chemist Award

Research
Our research group merges materials synthesis, photochemistry, and nonlinear optical photophysics expertise to conduct studies designed to provide the tenets for materials design and applications in the promising field of plasmonics. This research aims to establish the foundation for "radiative decay engineering" (RDE) by combining surface plasmon enhancement effects with nonlinear optical processes such as multiphoton absorption, energy transfer, and excited state intersystem crossing. Our objectives include a) the characterization and study of the structure-property relationship for new nonlinear optical materials with high three, four, and, perhaps, five-photon absorption cross-sections, b) the fabrication of new functionalized metal nanostructure "hybrid systems" to enhance high-order nonlinear absorption processes in fluorophores via SPR, and c) to gain control on the relaxation processes through radiative decay engineering on new composites.

Through radiative decay engineering in a hybrid system, we have recently proven, experimentally, for the first time, the possibility to enhance the fluorescence lifetime of organic chromophores, attaching them to metal nanospheres with their molecular dipole parallel to the metal surface. The hybrid system was a modified "di-conjugated" molecular probe, 4-Acetamido-4'-maleimidylstilbene-2,2'-dithiol, covalently bound to the surface of 3.5 nm diameter Au nanospheres by its two sulfur atoms, at a distance d < 1 nm, and with its molecular axis parallel to the surface of the nanoparticles surface. We measured a fluorescence lifetime increase of a factor two. We also found that the fluorescence quantum yield of this hybrid system is not reduced-proof of a weak energy transfer between the molecular probe and the nanoparticle.

These results demonstrate that a molecular dipole, oriented parallel to the metal surface, tends to be reduced by the coupling with its image. These results can strongly impact fields in biology and medicine, and our research, in general, can be applied to biological, chemical, and explosive sensing systems; biological imaging; and photodynamic therapy.

Purifying mercury-polluted water Using tiny pieces of gold and the properties of light, scientists can now quickly and inexpensively detect even trace amounts of the pollutant. In the near future, this process can be used to create water filters and reclaim contaminated water.

Most Recent Publications

2008

1. Leonardo De Boni, Carlos Toro, Artëm E. Masunov, and Florencio E. Hernández, "Untangling the Excited States of DR1 in Solution: An Experimental and Theoretical Study", J. Phys. Chem. A (In Press) 2008
2. Kevin D. Belfield, Mykhailo V. Bondar, Florencio E. Hernandez, Olga V. Przhonska, "Linear and nonlinear photophysical characterization and optical power limiting of fluorenylperylene diimide-based derivatives", J. Phys. Chem. B (In press) 2008
3. Carlos Toro, Arthur Thibert, Leonardo De Boni, Artem Masunov, and Florencio E. Hernández, "Fluorescence Emission of Disperse Red 1 in Solution at Room Temperature", J. Phys. Chem. B 112, 929 (2008)
4. Leonardo De Boni, Carlos Toro, and Florencio E. Hernández, "Pump polarization-state preservation of white-light supercontinuum generation", Optics Express. 2, 957 (2008)

2007

5. Kevin D. Belfield, Mykhailo V. Bondar, Florencio E. Hernandez, Olga V. Przhonska, Sheng Yao, "Two-Photon Absorption Cross-Section Determination for Fluorene Derivatives: Analysis of the Methodology and Elucidation of the Origin of the Absorption Processes", J. Phys. Chem. B 111, 12723 (2007)
6. Ion Cohanoschi, Carlos Toro, Athur Thibert, Shengli Zou, Florencio E. Hernández, "Surface Plasmon Fluorescence Enhancement on Gold Nanoparticles film Suspended at a Liquid-Liquid Interfaces", Plasmonics 2, 89 (2007)
7. D. S. Corra, L. De Boni, L. Misoguti, and C. R. Mendona, Ion Cohanoschi and Florencio E. Hernandez, "Z-scan theoretical analysis for three, four and five-photon absorption", Opt. Comm. 277, 440 (2007)
8. Horacio Carias, Manuel Marquez, Florencio E. Hernández, "A Wet Chemistry Method for the Construction of Silver Nanocapacitors", J. Nanoscience and Nanotehcnology 7, 1-4 (2007)
9. L. Petit, J. Griffin, N. Carlie, V. Jubera, M. Garc’a, Florencio E. Hernández, K. Richardson, "Luminescence properties of Eu3+ or Dy3+/ Au co-doped SiO2 nanoparticles", Mat. Lett. 61, 2879 (2007)
10. S. J. Andrasik, K. D. Belfield, M. V. Bondar, Florencio E. Hernandez, A. R. Morales, O. V. Przhonska, S. Yao, "One- and Two-photon Singlet Oxygen Generation with New Fluorene -based Photosensitizers", Chem. Phys. Chem. 8, 399 (2007)
11. Ion Cohanoschi, Sheng Yao, Kevin D. Belfield, Florencio E. Hernández, "Effect of the concentration of organic dyes on their surface plasmon enhanced effective two-photon absorption cross-section". J. Appl. Phys. 101, 86112 (2007)

2006

12. K. D. Belfield, M.Bondar, F. E. Hernandez, , O. Przkonska, S. Yao, "Two-photon absorption of a supramolecular psuedoisocyanine-J-aggregate assembly", J. Chemical Physics 320, 128-134 (2006)
13. Matt Rex, Florencio E. Hernandez, and Andres Campiglia, "Pushing the limits of mercury sensor with gold nanorods", Anal. Chem. 78, 445-451 (2006)
14. Ion Cohanoschi, Carlos, Toro, Florencio E. Hernández, "The impact of p-conjugation length on three-photon absorption cross-section of fluorine derivatives" J. Chem. Phys. 124, 194707 (2006)
15. Sheng Yao, Katherine J. Schafer-Hales, Ion Cohanoschi and Florencio E. Hernández, Kevin D. Belfield, "A Water Soluble Diaminostilbene Derivative as a Two-Photon Fluorescent Probe " Synlett. 12, 1863-1866 (2006)
16. Claudia C. Corredor, Kevin D. Belfield, Mykhailo V. Bondar, Olga V. Przhonska, Florencio E. Hernandez, Oleksiy D. Kachkovsky, "One and Two-Photon Photochromism of 3,4-Bis-(2,4,5-trimethyl-thiophen-3-yl)furan-2,5-dione" Journal of Photochemistry and Photobiology A: Chemistry. 184, 177 (2006)
17. Ion Cohanoschi, Marisol Garc’a, Carlos Toro, Kevin D. Belfield, Florencio E. Hernández, "Three-Photon Absorption of a New Series of Halogenated Fluorene Derivatives" Chem. Phys. Lett. 430, 133-138 (2006)
18. Ion Cohanoschi, Carlos Toro, Kevin D. Belfield, Florencio E. Hernández, "Solvent effects on the three-photon absorption cross-section of a highly conjugated fluorene derivative" J. Chem. Phys. 125, 161102 (2006)
19. Kevin D. Belfield, Mykhailo V. Bondar, Claudia C. Corredor, Florencio E. Hernandez, Olga V. Przhonska, Sheng Yao, "Two-photon photochromism of a diarylethene derivative enhanced by Fšrster's resonance energy transfer from two-photon absorbing fluorenes" Chem. Phys. Chem. 7, 2514 (2006)

2005

20. Ion Cohanoschi, Kevin D. Belfield, Florencio E. Hernández, "Three-Photon Absorption Enhancement in Symmetrical Charge Transfer Pull-Pull Fluorene Derivatives", Chem. Phys.Lett. 406, 462-466 (2005)
21. Florencio E. Hernández, Shenjiang Yu, Marisol Garc’a, AndrŽs D. Campiglia, "Fluorescence lifetime Enhancement of Organic Chromophores Attached to Gold Nanoparticle", J. Phys. Chem. B 109, 9499-9504 (2005)
22. Carlos Zapata-Rodriguez, Florencio E. Hernández, "Focal squeeze in axicons", Opt. Comm. 254, 3-9 (2005)
23. Ion Cohanoschi, Florencio E. Hernández, "Surface Plasmon Enhancement of Two- and Three-Photon Absorption of Hoechst 33258 dye in Activated Gold Colloid Solution", J. Phys. Chem. B 109, 14504 2005
24. I. Cohanoschi, A. Barbot, K. D. Belfield, S. Yao, Florencio E. Hernández, "Mega Three-Photon Absorption Cross-section Enhancement in Pseudoisocyanine J-Aggregates", J. Chem. Phys. 123, 231104 (2005)
25. Kevin D. Belfield, Mykhailo V. Bondar, I. Cohanoschi, Florencio E. Hernandez, Oleksiy D. Kachkovsky, Olga V. Przhonska, Sheng Yao, " Excited-state absorption and anisotropy properties of two-photon absorbing fluorene derivatives", Appl. Opt. 44, 7232-7238 (2005)
26. Kevin D. Belfield, Claudia C. Corredor, Alma R. Morales, Sheng Yao, Marie A. Dessources, and Florencio E. Hernandez, "Synthesis and characterization of new fluorene-based singlet oxygen sensitizers", J. Fluorescence 16, 105-110 (2005)
27. Ion Cohanoschi, Lorenzo Echeverr’a, Florencio E. Hernández, "Three-Photon Absorption Measurements in Hematoporphyrin IX: "Ground-breaking Opportunities in Deep Photodynamic Therapy" Chem. Phys. Lett. 419, 33-36 (2005)

2004

28. Florencio E. Hernández, Kevin D. Belfield, Ion Cohanoschi, "Symmetrical charge transfer enhances three-photon absorption in Fluorene Derivatives", Chem. Phys. Lett. 391, 22-26 (2004)
29. Kevin D. Belfield, Florencio E. Hernandez, Ion Cohanoschi, Mykhailo V. Bondar, Eric W. Van Stryland, Two-photons and Beyond: 2, 3, and 4 Photon Absorption in Conjugated Fluorenes, Polymeric Materials: Science and Engineering 91, 346-347 (2004)
30. Florencio E. Hernández, Kevin D. Belfield, Ion Cohanoschi, Mihaela Balu and Katherine. J. Schafer, "Three and Four-Photon Absorption of a Multiphoton Absorbing Fluorescent Probe", Appl. Opt. 43, 5394-5398 (2004)
31. K.D. Belfield, M.V. Bondar, Florencio E. Hernandez, A.R. Morales, O.V. Przhonska, and K.J. Schafer, "Nonlinear transmission and Excited-state absorption in fluorene derivatives", Appl. Opt. 43, 6339-6343 (2004)

Recent Highlights

1. Marisol Garcia, Celine Perego, Florencio E. Hernandez, “Truly Non Invasive Glucose Optical Sensor Using Gold Nanoparticles”, Chemical & Engineering News, (Web Site March 28, 2006) News of the Week April 03, 15 (2006)
2. F. E. Hernandez, “Physical Chemists Devise Quick Spectrometry-Based Mercury Test”, Video-Internet Interview and domestic TV-interview sponsored by the American Institute of Physics, USA, August 2006
3. F. E. Hernandez, “New glucose sensor using nanotechnology”, TV Interview for Central Florida News, Fox News-Channel 13, Orlando, Florida, August 2006
4. F. E. Hernandez, “New glucose sensor using nanotechnology”, TV Interview for Bay 9 News, Tampa, Florida, August 2006

Patents

1. F. E. Hernández, and D. Hagan, “Continuously-variable wavelength-independent polarization rotator (CVWI-PR)”, Patented (US-6,476,966 B1) (2002)
2. F. E. Hernández , Andres Campiglia, “Mercury sensor and water remediation using anisotropic gold nanoparticles” (Patent Pending) 2006
3. F. E. Hernández , “Truly Noninvasive Glucose Sensor” (Patent Pending) 2006

Research
Our research provides an excellent environment for interdisciplinary training for students at all levels, outstanding topics for graduate students to develop their research work in cutting-edge nonlinear optics, nano and biophotonics, and opportunities for enthusiastic undergraduate students through NSF-REU programs and UCF internal programs.