John Michael Collins
Bojan Jennings Professor of Physics
Office: Science Center 207
Office Hours: Tues. 2-3:30, Wed. 3 - 4:30
Phone: (508) 286-3976
Email: jcollins@wheatoncollege.edu
Degrees
Ph.D., M.A., Boston College
B.A., College of the Holy Cross
Main Interests
Physics, especially the interaction of radiation with matter; the role of science in society; Greek language; politics; sports (basketball, bicycling, golf); family,
Research Interests
1. 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, the most prominent being fluorescent lamp phosphors, laser, display screens (for televisions, computers, etc.). After absorbing material will often emit light that is characteristic of the atoms that make up the solid. We investigate the processes that take place following the absorption of light. These processes include multiphonon decay, energy transfer, upconversion, radiative decay, and vibronic processes. The materials of primary interest are crystals, powders, or glasses.
2. This year, our efforts are focused in four areas:
a. Luminescent properties of wide band emitters used in solid state laser applications. Basically, we examine transition metal ions such as Chromium isn a variety of crystals.
b. Spectroscopic investigation of rare earth ions in phosphors.
c. The use of group theoretical tools to relate the vibronic sidebands of sharp lines to the phonon density of states of a solid.
d. Construction of virtual crystals on the computer, and the modeling of energy transfer processes for various crystals, doping levels, and chemical parameters.
3. We collaborate with the computer science department to model the optical properties of materials so as to assist in the interpretation of the spectroscopic data. In particular, we construct virtual crystals on the computer (so far up to 160,000 atoms), and then place the rare earth or transition metal ions at the desired concentration. Those virtual atoms are made to "absorb" light, and then we trace the energy as it is transformed into either light or heat.
4. I have a strong interest in the development of materials used by the phosphor industry, particularly for medical and lighting applications. This research is supported in part by the General Electric Center for Global Research.
5. The Research Corporation Cottrell Science Award was awarded to Profs. John Collins and Xuesheng Chen for a proposal entitled "Light-shifts of Energy Levels of Rare Earth Ions in Solids." The experiment involves measuring the effect of a high intensity laser field on the energy levels in solid state laser materials containing rare earth ions. We constructed our own Q-switched Nd: YAG laser to be used in the project, and we also have the ability to frequency-double the output from the laser. The laser is used to study the light shifts, and also for laser spectroscopic studies of solids.
Teaching Interests
I enjoy teaching Physics at all levels. My most recent teaching interest is in transforming the Introductory Physics courses from a lecture-based course to a combined lab/lecture format. This new format provides students with the opportunity to gain immediate insights, through experimentation, of the material being presented in class. The format seeks to have students actively engaged in learning for the entire class, and is based on the TEAL teaching format developed in part at MIT.
As an experimental physicist, I am especially interested in providing students with meaningful laboratory experiences, from the introductory course to the senior thesis projects.
Courses taught include Introductory Physics I and II, Modern Physics I and II, Optics, Classical Mechanics, Electricity and Magnetism, Statistical Physics, Quantum Physics, Experimental Physics, The Physics of Music and Sound, and Electronic Circuits.
Student Projects
The major focus of the projects is on the optical properties of solid state laser materials. Radiative and nonradiative processes are of interest, particularly nonradiative energy transfer, and the role of phonons in affecting the efficiency of those processes.
There is also a smattering of other topics, including astronomy, engineering, and acoustics.
Projects are designed in part by the students, who know their interests better than anyone, and in part by the professor, whose expertise and advice are necessary for guidance.
Some student theses:
Jessical Tolson (07) Energy Transfer Processes in Yttrium Silicate
Nick aproberts-Warren (07) Group Theoretical Techniques in Analyzing Vibronic Transitions in Doped Crystals
Chris Steutzle (07) Computer Modeling and Visualization of Luminescent Crystals: The Role of Energy Transfer Upconversion
Jon McBee (04) Modeling of Delta Scudi Pulsating Stars
Ken Bycenski (01) Power and Temperature Dependence of Non-Radiative Decay in Er:Glass
B.J. Hansz (99) Coherent Transient Laser Spectroscopy: Light Shifts of Rare-Earth Ions in Solids
Jessica Krick (99) Two Stars Passing in the Night: An Analysis of Eclipsing Binary Systems
Adam Petri (98) Thermal Effects on Upconversion Dynamics of Er in YLF4 and Fluoride Glass
Jim Phillips (98) Construction and Characterization of a Q-Switched Nd:YAG Laser
Tara Healey (96) Theoretical and Experimental Investigations of Solid State Laser Systems
Some Recent Projects:
Construction of a Ti-sapphire laser
Non-destructive testing of beams under stress by wvae propagation analysis
Conversion of a golf cart from gas to electic power
"Gary the Gear Machine": An engineering art project inspired by the work of artist Arthur Ganson
Acoustic properties of waves in conical pipes
Selected Publications, Creative Work or Performances
Recent Presentations and Publications:
1. B. DiBartolo and .J. Collins, "Thermal Effects on the Spectral Characteristics of Laser Solids",to be published in "Frontier Developments in Optics and Spectroscopy" the Proceedings of the International School of Atomic and Moleular Spectroscopy, Erice, Italy, June 2007. To be published.
2. H. Orucu, G. Ozen, J. Collins and B. Di Bartolo, "Temperature Dependence of the Luminescence Spectra of Garnet Crystals Doped with Chromium Ions, presented at the International Workshop on Photonic Materials, Donostia (San Sebastian, Spain), July 4-6, 2007, to be published in Optical Materials
3. H. Orucu, G. Ozen, J. Collins and B. Di Bartolo, "Wide Band Luminescent Emitters: The Case of YAG:Cr" , presented at the Fall Meeting of the Electrochemical Society, Washington DC, October 2007.
4. "Luminescence as Materials Science", lectures given at summer school on "Frontier Developments in Optics and Spectroscopy" at the International School of Atomic and Moleular Spectroscopy, Erice, Italy, June 2007.
5. G. Ozen, J. Collins, B. Di Bartolo, and O Forte, " Up-conversion as a Discriminating Tool in Site-Selective Spectroscopy in Pr-doped Y3Al5O12", Journal of Applied Physics, 102, 023110 (2007) (8 pages) .
6. Nick 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.
7. Jessica 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.
8 . 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.
9. J. M. Collins, B. Di Bartolo and J. Tolson, "Spectroscopy and Kinetic Studies of Pr-Doped Yttrium Silicate", Proceedings of the 210th Meeting of the Electrochemical Society, Cancun, Mexico, October 29- November 3, 2006.
10. G. Ozen, O. Forte, B. Di Bartolo and J. Collins, "Dynamics of the Excitation and Up-convesrson Processes in doped YAlO3:Pr Single Crystals", J. Luminescence 125 1-2, 223-229 (2007)
11. J. Collins, G. Ozen, B. Di Bartolo, and O Forte, "Up-conversion at different sites in Pr-doped Y3Al5O12", presented at the International Conference on Luminescence, J. Luminescence 122-123, 447-449 (2007).
12. J. Tudisco and J. Collins, "Graphical and Statistical Modeling of a Doped Yttrium Aluminum Garnet ( Y3Al2(AlO4)3 ) Crystal", presented at the Consortium for Computing Sciences in Colleges, Northeast Region, April 21-22, 2006,Worcester, MA.
13. J. Tudisco and J. Collins, "Random and Non-random Distrubutions of Rare Earth Ions in Yttrium Aluminum Garnet (Y3Al2(AlO4)3) Crystal", presented at the Meeting of the American Physical Society, New England Section, March 31 - April 1, 2006 Boston, MA.
14. J. Collins, G. Ozen, and B. Di Bartolo, "Vibronic Studies of Optical Centers in YAG", presented at the Meeting of the Electrochemical Society, Los Angeles, October 2005.
15. J. Collins, "Luminescence Spectroscopy of Solids: Localized Systems", in Advances in Spectroscopy for Lasers and Sensing, B. Di Bartolo aand O. Forte, eds., Springer, 2006.