NORTHWESTERN UNIVERSITY NSF - PREM - MRSEC Synthesis and Characterization of Rare Earth Nanomaterials and their Biological and Photonic Applications Dhiraj Sardar Department of Physics University of Texas at San Antonio March 10 and 11, 2011

Outline Introduction to Rare Earths Methods Important Facilities Results – Theoretical and Experimental Potential Applications UTSA Physics Department -PREM PREM Students PREM Publications and Acknowledgements

Introduction to Rare Earths Electron charge distribution in different orbitals for RE ions showing the shielding of 4f electrons by outer 5s and 5p electrons Electronic Configuration (RE3+) : Incomplete inner 4fN orbital : [Xe]4fN5s25p6(N=113) Optical Properties : Strong absorption and fluorescence : Wide range of excitation and emission (UV-VIS-IR) Applications : Lasers, Display, Sensor, Therapy, Biomedical imaging, etc. Energy levels of trivalent rare earths (RE3+ )

Methods 1. Synthesis Solvothermal/Hydrothermal Precipitation Thermolysis 2. Morphology Characterization XRD, EDX SEM, TEM, STEM AFM 3. Optical Characterization Refractive Index Optical Absorption/Reflection/Scattering Steady State Emission Fluorescence Lifetime Optical Gain Efficiency(Internal, External, Conversion, Slope) FTIR/Raman Although there are 17 elements that are considered to be RE elements, 13 of them have been found to have potential laser activity when doped into crystalline or glass hosts. The RE are unique, in that, they exhibit sharp and well defined spectra (almost atomic-like) due to the unfilled 4f shells that are shielded by outer orbitals from perturbations.

Important Facilities Laser Research Laboratory Lasers: Argon, Nd:YAG, Ti:Sapphire, Diode (Vis-IR) Cary-14 Spectrophotometer SPEX 1250M Monochromator Cryogenic Cryostat Microscopy Laboratory STEM w/EDX HR-TEM w/EDX AFM Raman XRD JEOL-ARM200F(0.06 nm resolution)

RESULTS STEM imaging of the Nd3+ distribution Nd3+:Sc2O3 Blue = Scandium , Red = Oxygen

Theoretical (Judd-Ofelt Formalism) Radiative Process: (Judd-Ofelt Model) Major Nonradiative Processes: 1.Multiphonon relaxation (Amp) 2.Energy transfer between ions (AET) 3.Hydroxyl content/High frequency vibrational groups (AOH) 4.Impurity (Aimp) 4F7/2 AET 4S3/2 4F9/2 4I9/2 4I11/2 Amp 4I13/2 Although there are 17 elements that are considered to be RE elements, 13 of them have been found to have potential laser activity when doped into crystalline or glass hosts. The RE are unique, in that, they exhibit sharp and well defined spectra (almost atomic-like) due to the unfilled 4f shells that are shielded by outer orbitals from perturbations. 980nm Pump 550nm 650nm 1550nm AOH AET 4I15/2 Er3+ Radiative Quantum Efficiency: Arad=radiative decay rate Anr=nonradiative decay rate

Nd3+:Y2O3 Absorptions from Ceramic and Embedded in Polymers Nd3+:Y2O3 Ceramic Nd3+:Y2O3 in Epoxy Nd3+:Y2O3 in HEMA Polymer embedded samples yield similar spectral features to polycrystalline ceramic sample

RE3+:Y2O3 Emissions from Nanoparticles Epoxy embedded Eu3+:Y2O3 Nd3+:Y2O3

Comparative Results of Nd3+ in polymer, ceramic, and single crystals Parameter HEMAa Epoxyb Ceramicc Ceramicd Crystale Crystalf 2(10-20cm2) 6.75 10.97 10.52 4.09 8.55 4.08 4(10-20cm2) 8.47 5.68 5.06 2.97 5.25 5.53 6(10-20cm2) 3.65 5.37 5.28 3.85 2.85 3.97 rad (ms) 0.623 0.549 0.532 0.354 0.655 0.589 fl (ms) 0.584 0.499 0.504 0.318 - *Q(%) 93.7 90.9 94.7 89.0 *Internal radiative quantum efficiency a,b,c Sardar et al., Polymer Internationa (2005), J. Appl Phys. (2004, 2005) d Kumar et al., IEEE J Quant. Elect.(2006) E Kaminskii, Laser Crystals, (1996) f Morrison et al., J.Chem. Phys (1983)

Other RE-Doped Materials and their Potential Applications Transparent Nd:YAG Ceramic Nd:YAG Single Crystal Yb,Er :Phosphate Glass Inset:Pr :Phosphate Glass Eu:Y2O3 :HEMA Polymer YbTm YbEr YbEr YbEr SrS:EuDy Eu Tb Eu2+ Eu:Y2O3 nanoparticles (Homogeneous precipitation) Host: La2O2S Top: 980 nm Ex (10mW) Bottom: 320 nm Ex: Up and Down Conversion (Imaging, Display, Therapy, Sensing, Security, Lighting, etc.)

What is so Unique about RE (Nd3+) for Biomedical Applications? absorption emission Large Stoke’s shift (~500nm) & strong emission Multi-frequency absorption & emission Long fluorescence lifetimes Optical properties “independent” of size Nontoxic However, they usually contain toxic elements such as cadmium. Rare-earth (RE) nanophosphors, in comparison, offer an alternative for biological labeling and medical diagnostics due to their large Stokes shift, sharp emission spectra, long lifetime, multiphoton and up-conversion excitation, low toxicity and reduced photobleaching over quantum dots and organic phosphors molecule. These materials have the ability to emit intensely at various wavelengths by an appropriate choice of color-center elements instead of varying particle size.

Imaging Application of RE Nanoparticles Present technology: Organic Dyes and Quantum Dots Advantages-Highly Fluorescent Disadvantages-UV excitation causes autofluorescence, reducing S/N ratio -Size tunability is needed for quantum dots for proper excitation -Toxicity of the composition, Photobleaching Color tunable Q dots a b Live cell (mouse fibroblast) image with green upconversion under 980 nm Exc. (b) Cell autofluorescence under UV Exc. Confocal image of the 980 nm excited Emissions (550 and 670 nm) from Yb,Er:CaF2 Nanoparticles Autofluorescence After background subtraction Future technology: Rare Earth-doped Nanoparticles Advantages-Highly Fluorescent, wide range of excitation and emission (UV-IR), no autofluorescence, nontoxic, no size requirement, no photobleaching

Photodynamic Therapy with IR Upconversion (IPDT) Advantages: IR Upcoversion, 5 times penetration depth compared to Current UV-X PDT

UTSA Physics Department- PREM Advanced Engineering and Technology (AET) Building ($82.5M; December 2009) Physics Department occupies the 3rd floor (over 14,000 sq. ft. of lab space) $11.2M spent by UTSA to Renovate Physics Research Laboratories Thin Films Laboratory (AET) ALD, Laser Deposition Biophotonics Research and Imaging Laboratory (AET) Synthesis Labs (AET) Nanomaterials Nanophotonics and Laser Materials Terahertz Laboratory (AET) Computational Physics Laboratories (AET) Access to the Texas Advanced Computing Center (TACC at UT Austin) Advanced Microscopy Laboratory (Science Building) TEM-STEM, SEM, AFM, Raman Including the most advanced spherical aberration corrected STEM (JEOL ARM 200F) Tenure-track faculty Total: 13; PREM: 7 6 Minority; 3 Women 2 Hispanic Women 1 African American Woman

UTSA PREM Researchers Dr. Jianhui Yang (2010) Dr. Ajith Kumar (2011) Erik Enrique Joseph Barrios Edward Khachatryan Robert C. Dennis Brian Yust Leland Page Kenneth Ramsey Madhab Pokrhel Nathan Ray Francisco Pedraza Devraj Sandhu Jesse Salas Hector Barron-Escobar Marcus Najera Gilberto Cassilas Garcia Zurab Kereselidze

PREM Publications (2010-11) Published or in Press: Chandra, S.*, Francis Leonard Deepak, J. B. Gruber, and D. K. Sardar, “Synthesis, Morphology, and Optical Characterization of Er3+:Y2O3”, J. Chem. Physics C, 114, 874-880 (2010).  Burdick, G. W., J. B. Gruber, K. L. Nash, and D. K. Sardar, “Analyses of 4f11 Energy Levels and Transition Intensities Between Stark Levels of Er3+ in Y3Al5O12”, Spectroscopy Letters: 43, 406-422 (2010). Gruber, J. B., G. W. Burdick, S. Chandra*, and D. K. Sardar, “Analyses of the Ultraviolet Spectra of Er3+ in Er2O3 and Er3+ in Y2O3”, J. Appl. Phys., 108, 023109: 1-7 (2010). Chandra, S.*, J. B. Gruber, G. W. Burdick, and D. K. Sardar, “Material Fabrication and Crystal-Field Analysis of the Energy Levels in Er3+ doped Er2O3 and Y2O3 Nanoparticles Suspended in Polymethyl Methacrylate”, J. Appl. Pol. Sci. (in Press) (2011). Yang, J. and D. K. Sardar, “One-Pot Synthesis of Coral-Shaped Gold Nanostructures for Surface-Enhanced Raman Scattering”, J. Nano Res. (in Press) (2011). Yang, J., R. C. Dennis*, and D. K. Sardar, “Room-Temperature Synthesis of Flowerlike Ag Nanostructures Consisting of Single Ag Nanoplates”, Mater. Res. Bull. (in Press) (2010). B. Yust*, D. K. Sardar, and A. T. Tsin, "Phase conjugating nanomirrors: utilizing optical phase conjugation for imaging", SPIE Proceedings, Vol. 7908 (In Press) (2011). Francis Leonard Deepak, Rodrigo Esparza, Belsay Borges, X. Lopez-Lozano, Miguel Jose Yacaman, Rippled and Helical MoS2 Nanowire catalysts – An aberration corrected STEM study. Catalysis Letters, In Press, 2011. Page, L*, Maswadi, S, Glickman, RD, “Optoacoustic Spectroscopic Imaging of Radiolucent Foreign Bodies”, in Medical Imaging 2010: Ultrasonic Imaging, Tomography, and Therapy, D'hooge, J; McAleavey, SA, Eds., Proc. SPIE, Vol. 7629, pp 7629OE-1 – 7629OE-7, 2010. Maswadi*, S, Glickman, RD, Elliott, WR, Barsalou N,. “Nano-Lisa for In Vitro Diagnostic Applications”, in Photons Plus Ultrasound: Imaging and Sensing 2011, Oraevsky AA, Wang LV, Eds, Proc. SPIE, Vol. 7899, in Press, 2011. Page, L*, Maswadi, S, Glickman, RD, “Identification of Radiolucent Foreign Bodies in Tissue Using Optoacoustic Spectroscopic Imaging”, in Photons Plus Ultrasound: Imaging and Sensing 2011, Oraevsky AA, Wang LV, Eds., Proc. SPIE, Vol. 7899, in Press, 2011. Francis Leonard Deepak, G. Casillas-Garcia*, H. Barron*, R. Esparza and M. Jose-Yacaman, New Insights into the structure of Pd-Au nanoparticles as revealed by aberration-corrected STEM”, in Press, 2011 V. H. Romero, W. Egido, Z. Kereselidze*, C. M. Valdez, .E. Michaelides, X. G. Peralta, M. Jose-Yacaman, F. Santamaria. Neurons preferentially internalize goldnanostars with strong and precise photothermal properties. Submitted to Nanomedicine NBM, 2011. X. G. Peralta, “Plasmon modes for terahertz detection: Terahertz Plasmon modes in grating coupled double quantum well field effect transistors”, released by LAP Lambert Academic Publishing (2010-08-30) - ISBN-13 : 978-3-8383-9371-1 (2010). Wilmink, G. J., Rivest, B. D., Roth, C. C., Ibey, B. L., Payne, J. A., Cundin, L. X., Grundt, J. E., Peralta, X., Mixon, D. G. and Roach, W. P. , “In vitro investigation of the biological effects associated with human dermal fibroblasts exposed to 2.52 THz radiation”. Lasers in Surgery and Medicine, n/a. doi: 10.1002/lsm.20960, 2011. J. Antunez-Garcia, S. Mejia-Rosales, E. Perez-Tijerina, J. M. Montejano-Carrizales and M. Jose –Yacaman. “Coallescence and collision of gold nanoparticles”. Materials, 4: 368-379, doi:10.3390/ma4020368, 2011. 16 Published, 4 other papers submitted, and 11 more under preparation All Publications Acknowledge NSF-PREM Support: Grant No. DMR-0934218