Welcome to the Sears Group at Stony Brook University!

    Our group focuses on 
developing new high resolution and high sensitivity laser spectroscopic 
techniques
to study molecules. The techniques are applied to prototype molecular systems 
in order to understand their structure, dynamics and photophysics in the gas phase.  Recent frequency comb-referenced experiments provide some of the highest accuracy measurements of their kind.

Using high resolution photoelectron methods like the resonance enhanced multiphoton ionization (REMPI), we study the vibrational structure of the first excited states (S1) and cation ground state (D0) of small aromatic molecules like phenylacetylene and benzonitrile. The slow electron velocity mapping (SEVM) electron imaging technique helps us to study the photoelectron angular distributions. Theoretical methods using electronic structure and vibronic interaction programs are being developed to predict the vibrational structure of an electronic transition. We are involved in comparing our experimental spectra with those we calculated in an effort to validate our theoretical results. 

    The group is also working on implementing frequency comb-referenced techniques.  The development of this new technology was the basis for the award of the Nobel prize in Physics in 2005 to T. Hänsch and J. Hall.  In our laboratory, we have an Er-fiber laser based comb operating in the near infrared. It provides  an optical frequency standard with an accuracy and precision of approximately 1 part in 1012.  Lasers locked to this standard are used to make exceptionally precise and accurate measurements of molecular absorption lines.  Current work is focused on the measurement of pressure broadening and shifts in lines of the acetylene near-infrared spectrum. These measurements are essential for the calibration of remote sensing measurements in the atmosphere and also for understanding satellite and astronomical measurements of planetary atmospheres.  Line position measurements are also made using saturated absorption spectroscopy.


  

*******We are currently looking for one or two new graduate students*******
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