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

IntroductionExperiment Far-infrared absorption  Glucose and sucrose  Glucose and sucrose  Uric Acid & its derivative  Uric Acid & its derivative Temperature & structural dependent absorption Conclusions Contents

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

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

Sample preparation  pellets ( mm) with matrix for low temperature measurements (polyethylene:sample::8:1) measurements (polyethylene:sample::8:1)  pure sample pellets ( mm) for room temperature measurement – to observe distinct peaks measurement – to observe distinct peaks

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

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

Dependence on crystallanity  Intermolecular vibrational modes

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

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

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

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

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

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

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

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