Terahertz-Regime Attenuation Signatures in Bacillus subtilis and a Model Based on Surface Polariton Effects

A summary is provided for terahertz attenuation signatures measured in spore-laden samples of Bacillus subtilis in three different forms: 1) concentrated powder; 2) dilute powder; and 3) aerosol. In addition to a surprising spectral narrowness, some signatures also display an increase in peak signat...

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Bibliographic Details
Published in:IEEE sensors journal 2006-10, Vol.6 (5), p.1076-1083
Main Authors: Brown, E.R., Khromova, T.B., Globus, T., Woolard, D.L., Jensen, J.O., Majewski, A.
Format: Article
Language:English
Subjects:
Aerosols
Attenuation
Attenuation measurement
Bacillus subtilis
Biomedical optical imaging
Displays
Electromagnetic modeling
ellipsoidal particle scattering
Fungi
Optical attenuators
peptidoglycan
Phonons
polariton
Polaritons
Powders
resonant polarizability
Signatures
spore coat
Spores
Submillimeter wave measurements
transverse optical phonon
Vibration
Walls
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Summary:A summary is provided for terahertz attenuation signatures measured in spore-laden samples of Bacillus subtilis in three different forms: 1) concentrated powder; 2) dilute powder; and 3) aerosol. In addition to a surprising spectral narrowness, some signatures also display an increase in peak signature strength (per spore) with dilution of the sample. A model is constructed to explain this phenomenology based on the presence of optical phonons and electromagnetic interaction with the spore wall. Specifically, the spheroidal Bacillus spores admit surface modes that interact with radiation via polaritonic coupling and are underdamped if isolated from each other through a dilution or aerosol levitation. Hence, the results defy longstanding assumptions that the biomolecular-related terahertz vibrations are necessarily overdamped and have immeasurably weak attenuation
ISSN:1530-437X
1558-1748
DOI:10.1109/JSEN.2006.881354