Luminescence Spectroscopy of Solids

There is an ongoing effort, in collaboration with a group at Boston College, to investigate the luminescent properties of solid-state laser materials, particularly rare earth ion- and transition metal ion-doped insulators. These materials are used for several applications, including lamp phosphors, lasers, display screens (for televisions, computers, etc.), and scintillators (for medical imaging). These materials are useful because, after absorbing energy, they emit light that is characteristic of the atoms that make up the solid. We investigate the processes that take place following the absorption energy. These processes include radiative decay (the emission of light), non-radiative decay (the conversion of energy into heat), and how energy is transferred among the ions in the solid.

Currently our efforts are focused in the following areas:

  • The properties of oxides materials with metal-metal charge transfer states for potential application in solid state lighting devices
  • An investigation into rare-earth ion doped phosphors for use in medical imaging systems
  • Luminescent properties of nanoparticles doped with rare earth and transition metal ions, particularly on the role of surface states and on confinement effects.
  • Upconversion processes as a tool in site-selective spectroscopy.
  • Downconversion as method for increasing the efficiency of solar cells.

In recent years, I have had the pleasure of participating in schools and workshops at the International School of Atomic and Molecular Spectroscopy, which meet in Erice, Sicily during the summers. The topics cover the physics of optical materials, with the most recent workshop (2012) on “New Developments in Inorganic Luminescent Materials. Learn more about the Erice summer schools.

Recent and Current Support

This work is supported by the National Science Foundation under the following grants:

  • National Science Foundation: Award 1126337, MRI: Acquisition of a pulsed laser/detection system for time-resolved studies of molecular complexes
  • National Science Foundation: Award 1105907, RUI: Investigation of metal-to-metal charge transfer states in rare earth ion-doped solids (Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.)
  • OSRAM Sylvania Corp.
  • General Electric Corp.

Recent Student Research

Publications / Presentations
  • Srivastava, M. Jennings, and J. Collins, “The Interconfigurational (4f15d1 to 4f2) Luminescence of Pr3+ in LuPO4, K3Lu(PO4)2 and LiLuSiO4”, Optical Materials 34, 8, ( 2012) 1347-1352.
  • J. Collins, M. Geen, B. Di Bartolo, and M. Bettinelli, Thermal and Concentration Dependence of Cross-Relaxation in Pr-doped YPO4, Journal of Luminescence (2012) http://dx.doi.org/10.1016/j.jlumin.2012.04.027
  • J. Collins, Y. Tsehay, J. Long, P. Boutinaud, R. Boonsin, G. Chadeyron, “Spectroscopy of Pr-doped CaTiO3 under UV excitation”, Meeting of the Electrochemical Society, Honolulu, Hawaii, October 7-12, 2012. (Yohannes Tsehay and Judy Long are Wheaton class of 2014.)
  • T. Bennett and J. Collins, “Luminescence Properties of Pr-Doped Lithium Niobate”, Northeast Undergraduate Research and Development Symposium (NURDS) at the University of New England in Biddeford, ME, March 10-11, 2012. (Tyler Bennett is Wheaton Class of 2012.)
  • J. Collins, M. Bettinelli, P. Boutinaud, M. Geen, B. Di Bartolo, and J. García Sole, “Relaxation via the Intervalence Charge Transfer (IVCT) State in Pr3+-Doped LiNbO3: A Kinetic Approach, to be presented at the International Conference on Luminescence, June 26 – July 1, 2011. (Megan Geen is Wheaton class of 2012)
  • J. Collins, J. Grassetti, K Mishra, D. Hamby, J. McKittrick, J. Tao, S. Shimizu, J Talbot, and B. Di Bartolo, Structural And Optical Properties of ZnO-based Alloys, presented at the Meeting of the Electrochemical Society, Honolulu, HI, October, 2008. ECS Transactions, December, 2008.
  • J. Collins, M. Jennings, J. S. Vartuli, S. J. Duclos, and A. Srivastava, “Luminescence of Pr3+ in LuPO4”, presented at the International Conference on Luminescence and Optical Spectroscopy of Condensed Matter, Lyon, France, July, 2008.
  • N. apRoberts Warren, J. Collins, R. Wall, B. Di Bartolo, “Theoretical Studies of Vibronic Transitions of Optically Active Centers in Crystals”, presented at the Spring Meeting of the New England Section of the American Physical Society, Orono, ME, April 2007. (Nick apRoberts-Warren is Wheaton class of2007.)
  • J. Tolson, J. Collins, B. Di Bartolo, “Cross-Relaxation and Diffusion of Energy in Pr-doped Yttrium Silicate”, presented at the Spring Meeting of the New England Section of the American Physical Society, Orono, ME, April 2007. (Jessy Tolson is Wheaton class of 2007.)
  • C. Stuetzle, J. Collins, and M. Gousie, “Stochastic Modeling of Decay Processes in Crystals with Random and non-Random Placement of Ions”, presented at the Spring Meeting of the New England Section of the American Physical Society, Orono, ME, April 2007. (Chris Steutzle is Wheaton class of 2007.)