Pat Kambhampati

Pat KambhampatiProfessor

B.A. (Carleton College, 1992)
Ph.D. (University of Texas at Austin, 1998)
Postdoctoral Research Associate (University of Texas at Austin, 1999-2001)

Contact Information

Office: Otto Maass 423
Phone: (514)398-7228
Email: Pat.Kambhampati [at] McGill.CA
Lab: Otto Maass 25
Lab Phone: (514)398-3455
Web Page: Kambhampati Group Website

Research Themes

  • Chemical Physics 
  • Materials Chemistry

Research Description

Research in the Kambhampati group focuses on energy, its dynamics, its manifestation in novel materials, and in the deployment of advanced measurement techniques of energetic processes. Consider that the sunlight that reaches the earth could be harnessed, on the supply side of basic energy science. Consider that the energy that powers room lighting could support walls that are lit up white, on the demand side of basic energy science. At the heart of these applications and visions of the future is the development of novel energetic materials. It is our role in this multifaceted problem to focus on the measurement of the motion of charges in energetic materials.

Towards this goal, we have developed a suite of three state-of-the-art experimental methods for probing electronic processes and apply them to the leading systems in modern materials science. Our group has three state-of-the-art laser spectroscopic instruments, each of which alone makes this an unusually powerfully equipped lab. Having three complementary spectroscopies, however, renders our lab truly uniquely equipped in the world to unravel electronic processes in electronic materials. Our group has recently developed non-classical optics based methods to perform Two Dimensional Electronic (2DE) spectroscopy, the optical analog of 2D-NMR. Prior to that our group had developed State-Resolved Pump/Probe (SRPP) spectroscopy. Most recently we have implemented a time-resolved photoluminescence (t-PL) instrument with the fastest time resolution in the world for an instrument of its kind. With 2DE spectroscopy we can probe the primary steps in electronic excitations on the timescale of 10 – 1000 femtosecond. With SRPP spectroscopy we can probe the next steps in the energetic cascade from 0.1 to 100 picoseconds. With the final step of t-PL spectroscopy we can probe from 2 to 2000 ps. The three spectroscopies are illustrated in the adjacent image. 

In our group we have historically studied semiconductor quantum dots (QD) and have done pioneering work in the field of exciton dynamics in quantum dots. QD have been a model system for years for optoelectronic applications and now see commercial use in flat panel displays. They remain a model system for explore quantum processes in materials. The simple idea is that if you make a make a semiconductor to be as small as the electron Bohr radius, you get to see all sorts of rich quantum mechanical effects. This transformation happens for QD that are about 5 – 10 nm in size, depending upon the material. When the charges are quantum confined, there are a host of changes to the electronic structure and dynamics in response to excitation. We focus on the dynamics of the electrons upon excitation by ultrashort laser pulses. We are able to observe the evolution of quantized charges from electronic decoherence to relaxation to recombination. Shown in the adjacent image is 2DE spectra of the primary steps in electron dynamics – quantum decoherence.

Semiconductor perovskites on the other hand are a very new material, dramatically appearing on the materials stage in 2014 for their performance in photovoltaics. What physical and chemical effects give rise to their remarkable performance and properties? These are some of the questions we aim to ask with our world leading electronic spectroscopy lab. One of the most remarkable aspects of semiconductor perovskites is that they are tolerant to defects unlike the semiconductors which have formed the backbone of the high tech industry for the past 50 years. This defect tolerance arises because perovskites maintain liquid / solid duality. That is the material is a crystal for the electrons but a glass for the lattice. It is our aim to unravel the remarkable physical properties of semiconductor perovskites using our world leading electronic spectroscopy facility. Shown in the adjacent image is our visualization of a quantum drop instead of a conventional quantum dot. The idea of a quantum drop is that the lattice behaves in a liquid like manner to solvate charges and give rise to quantum confinement effects, but in a bulk system.

These dynamics we observe are some of the most exciting physical processes seen in materials in decades. And we are able to obtain first glimpses of their novel behavior and use that to add value to the global effort for our energy future.

 

Currently Teaching

CHEM 203 Survey of Physical Chemistry 3 Credits
    Offered in the:
  • Fall
  • Winter
  • Summer

CHEM 204 Physical Chem/Biological Scis1 3 Credits
    Offered in the:
  • Fall
  • Winter
  • Summer

 
Back to top