Can a "radiationless transition" actually radiate an electromagnetic pulse? Can we determine the direction of intramolecular electron transfer without making any assumptions whatsoever? Can we monitor charge transfer without relying on indirect evidence such as fluorescent probes?

How fast does an optoelectronic switch close? After closing, how well does it conduct electricity? For how long does it remain conductive? How does photoconductivity in nanocrystalline TiO₂ or CdSe quantum dots differ from that of their bulk counterparts?

How do solvent molecules respond to photoexcitation of a nearby dye molecule? How is hydrogen bonding in water and methanol affected by dilution with organic solvents such as acetone and acetonitrile? Is it enhanced or diminished? How are collective low frequency solvent modes affected by dilution? Do they behave ideally? How does nanoscale confinement affect librational dynamics in water?

These are the types of fundamental questions about the world around us being answered in the Schmuttenmaer Group. A unifying theme is the realization that far-infrared (or terahertz) probes can provide the answers. Therefore, we have developed experimental techniques that monitor low frequency motions and absorptions directly.

A little background ...

These types of experiments are typically referred to as THz spectroscopy. Taken literally, THz spectroscopy implies frequencies on the order of a few THz. Since 1 THz = 33.33 wavenumbers, THz spectroscopy covers the range from about 3 wavenumbers to about 600 wavenumbers. Therefore, any work done in this region of the spectrum can rightfully be regarded as THz spectroscopy. However the connotations of this terminology, especially in the context of "THz time domain spectroscopy", or "Time-Resolved THz Spectroscopy" are that it implies generation and detection of THz pulses in a synchronous, coherent manner using visible laser pulses.

 

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