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Prashanth Upadhya, Yao-Chun Shen, Giles Davies & Edmund Linfield

Terahertz Time-Domain Spectroscopy of Glucose and Uric Acid . Prashanth Upadhya, Yao-Chun Shen, Giles Davies & Edmund Linfield . Cavendish Laboratory, Cambridge University. Contents. Introduction Experiment Far-infrared absorption  Glucose and sucrose  Uric Acid & its derivative

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Prashanth Upadhya, Yao-Chun Shen, Giles Davies & Edmund Linfield

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  1. Terahertz Time-Domain Spectroscopy of Glucose and Uric Acid Prashanth Upadhya, Yao-Chun Shen, Giles Davies & Edmund Linfield Cavendish Laboratory, Cambridge University

  2. Contents Introduction Experiment Far-infrared absorption Glucose and sucrose  Uric Acid & its derivative Temperature & structural dependent absorption Conclusions

  3. Introduction many intrinsic resonances predicted in the THz regime vibrational modes in polynucleotides …Powell et al  base twisting and librational modes in DNA structure … Young et al low frequency collective vibrational modes  distinguish between different isomeric configurations in retinal molecules …Walther et al  finger print of conformational state – benzoic acid …Walther et al

  4. Vacuum capable THz-TDS set-up useful bandwidth of 0.1- 3.0 THz  spectral resolution of better than 1 cm-1

  5. Sample preparation pellets (1.2-1.4mm) with matrix for low temperature measurements (polyethylene:sample::8:1)  pure sample pellets ( 0.3- 0.7mm) for room temperature measurement – to observe distinct peaks

  6. Particle size – ESEM measurement  Submicron particle size – minimise scattering effect on observed spectra

  7. Far-infrared absorption in Glucose

  8. Far-infrared absorption in Glucose D-Fructose L-Glucose D-Glucose

  9. Dependence on crystallanity  Intermolecular vibrational modes

  10. Absorption in molecule containing glucose structure

  11. Absorption in molecule containing glucose structure Sucrose L-Glucose  absorption tend to depend on molecular environment

  12. L-Glucose - absorption peaks at low temperature  many distinct absorption peaks at low temperature

  13. We observed terahertz absorption as a result of intermolecular interaction & also dependence on structural change in a molecule ……… in other molecules?

  14. Far-infrared absorption in Uric Acid

  15. Far-infrared absorption in Uric Acid Allantoin Uric Acid  structural dependence of absorption

  16. Temperature dependence Uric Acid Allantoin  stronger temperature dependence in allantoin  change in energy surfaces of molecules at low temperature

  17. Uric Acid - absorption line profile  change in position and width of peaks with temperature

  18. Conclusions • Demonstrated use of THz-TDS to study far-infrared response of some isomeric and derived structures of glucose and uric acid • Observed absorption due to collective intermolecular modes • Strong temperature and structural dependence of absorption • Theoretical model analysis required to understand the underlying dynamics

  19. Acknowledgements EPSRC Royal Society Toshiba Research Europe Association of Commonwealth Universities and thanks to Dr. M. B. Johnston Dr. A. Dowd

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