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RAP opportunity at National Institute of Standards and Technology     NIST

State Resolved THz and Ultraviolet Studies of Polypeptide Structure and Dynamics


Physical Measurement Laboratory, Applied Physics Division

opportunity location
50.68.62.B5923 Boulder, CO

NIST only participates in the February and August reviews.


name email phone
David Francis Plusquellic 303-497-6089


Terahertz (THz) radiation interrogates the lowest frequency collective motions of biomolecular systems. These collective modes characterize the incipient motions for the large-scale conformational changes along the torsional coordinates responsible for the flexibility of protein, polynucleotide, and polysaccharide backbones during folding and activation. THz studies are a sensitive probe of crystalline order, conformational form, peptide sequence, solvent interactions, H-bonding force constants, and anharmonic character of the force fields.  Continuous-wave and phase-coherent chirped-pulse methods are used to measure the spectra of bulk (pellet) samples, thin-film samples on waveguide interfaces and gas phase samples over temperature ranges from 1.7 K to 350 K. The experimental results are modeled using high-level quantum mechanical methods (DFT/MP2/MRCI) to characterize the nuclear motions associated with the observed THz features. 

New methods based on electro-optical dual-optical-frequency combs and room-temperature multi-heterodyne detection are under development to enhance sensitivity across the region from 0.05 to 2 THz. 

In other research areas, chirped pulse THz measurements are performed using amplifier/multiplier chains in a long pass (White) cell on samples prepared in a slit jet nozzle and from an effusive beam source. Fragmentation products are detected after passing the seeded gas through a heated quartz pyrolysis source or following electric discharge in a pulse nozzle source. Other THz applications are to studies of the magnetic spin flip transitions (magnons) in anti-ferromagnetic materials and to voltage standards using superconducting Josephson junctions.  In the UV, the doubled output from continuous-wave ring-dye and ring-Ti:Sapphire lasers are used to perform UV studies of biomolecules at a sub-Doppler resolution of 3 MHz to 20 MHz.

key words
Biophotonics; Biomolecules; THz spectroscopy; Electro-optic Dual-optical-frequency THz Combs; Chirped Pulse THz; Polypeptides; Quantum Chemical Theory; Vibrational anharmonicity


Citizenship:  Open to U.S. citizens
Level:  Open to Postdoctoral applicants


Base Stipend Travel Allotment Supplementation
$82,764.00 $3,000.00
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