[MOS] October 16, 2012

[Zina M Queen]

Seminar on

Modern Optics and Spectroscopy

Adventures with chirped-pulse

millimeter-wave spectroscopy

 

Kirill Prozument,

Massachusetts Institute of Technology

 Tuesday, October 16, 2012

12:00 – 1:00 p.m. 


Recent development of the chirped-pulse Fourier transform microwave (CP-FTMW) spectroscopy by Brooks Pate and coworkers has revolutionized the field of microwave spectroscopy. Large spectral regions (~10 GHz) are covered instantly with high resolution (~100 kHz) and meaningful relative intensities of the transitions. Chirped-pulse millimeter-wave (CPmmW) spectroscopy developed recently in the Field group at MIT is an extension of the CP-FTMW technique to the millimeter-wave (mm-wave) region of 70–100 GHz.

            The technique opens new possibilities in spectroscopic studies ranging from light–matter interaction to chemistry of aldehydes and ketones. The following topics will be covered in this talk:

CPmmW spectroscopy of Rydberg-Rydberg transitions is Ca atoms. Atoms and molecules in Rydberg states have unusually high polarizability and the transition dipole moments on the order of 103 Debye. The populations and coherencies of Rydberg states are easily manipulated with CPmmW. Direct detection of coherent mm-wave radiation from such transitions is detected with CPmmW, and reveals the collective effects of interaction between the Rydberg atoms and the mm-wave field.

Chemistry mediated by free H atoms is studied by CPmmW spectroscopy. Unimolecular decomposition reactions, initiated by photolysis or pyrolysis, reveal the basic chemical mechanisms, and have been at the core of physical chemistry research. Bimolecular reactions involving free H atoms seem to be playing a key role in thermal decomposition of aldehydes and ketones, and have been studied with CPmmW spectroscopy. Extension of this experimental approach to more complex systems that are relevant to biomass decomposition will be discussed.

 

 

Grier Room, MIT Bldg 34-401

Refreshments served after the lecture
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