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Prashanth Upadhya, Yao-Chun Shen, Giles Davies & Edmund Linfield Prashanth Upadhya, Yao-Chun Shen, Giles Davies & Edmund Linfield
Terahertz Time-Domain Spectroscopy ofTerahertz Time-Domain Spectroscopy ofGlucose and Uric Acid Glucose and Uric Acid
Cavendish Laboratory, Cambridge UniversityCavendish Laboratory, Cambridge University
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IntroductionIntroduction
ExperimentExperiment
Far-infrared absorptionFar-infrared absorption
Glucose and sucroseGlucose and sucrose
Uric Acid & its derivativeUric Acid & its derivative
Temperature & structural dependent absorptionTemperature & structural dependent absorption
ConclusionsConclusions
ContentsContents
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IntroductionIntroduction
many intrinsic resonances predicted in the THz regime many intrinsic resonances predicted in the THz regime vibrational modes in polynucleotidesvibrational modes in polynucleotides … …Powell et al Powell et al
base twisting and librational modes in DNA structurebase twisting and librational modes in DNA structure …… Young et alYoung et al
low frequency collective vibrational modes low frequency collective vibrational modes distinguish between different isomeric configurations in retinal moleculesdistinguish between different isomeric configurations in retinal molecules … …Walther et al Walther et al
finger print of conformational state – benzoic acidfinger print of conformational state – benzoic acid ……Walther et al Walther et al
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Vacuum capable THz-TDS set-upVacuum capable THz-TDS set-up
useful bandwidth of 0.1- 3.0 THz useful bandwidth of 0.1- 3.0 THz
spectral resolution of better than 1 cmspectral resolution of better than 1 cm-1-1
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Sample preparationSample preparation
pellets (1.2-1.4mm) with matrix for low temperature pellets (1.2-1.4mm) with matrix for low temperature measurements measurements (polyethylene:sample::8:1)(polyethylene:sample::8:1)
pure sample pellets ( 0.3- 0.7mm) for room temperaturepure sample pellets ( 0.3- 0.7mm) for room temperature measurement – to observe distinct peaks measurement – to observe distinct peaks
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Particle size – ESEM measurementParticle size – ESEM measurement
Submicron particle size – minimise scattering effect on Submicron particle size – minimise scattering effect on observed spectraobserved spectra
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Far-infrared absorption in GlucoseFar-infrared absorption in Glucose
D-GlucoseD-Glucose
L-GlucoseL-Glucose
D-FructoseD-Fructose
0.5 1.0 1.5 2.0 2.5
0
10
20
30
40
50
60
Abs
orpt
ion
(a.u
.)
Frequency (THz)
D-Fructose L-Glucose D-Glucose
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Dependence on crystallanityDependence on crystallanity
0.5 1.0 1.5 2.0 2.5 3.0
0
5
10
15
20
25
Abs
orpt
ion
(a.u
.)
Frequency (THz)
Crystalline Solution
Intermolecular vibrational modesIntermolecular vibrational modes
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Absorption in molecule containing glucose Absorption in molecule containing glucose structurestructure
absorption tend to depend on molecular absorption tend to depend on molecular environmentenvironment
L-GlucoseL-Glucose
SucroseSucrose
0.5 1.0 1.5 2.0 2.5 3.0
0
5
10
15
20
25
Abs
orpt
ion
(a.u
.)
Frequency (THz)
Sucrose L-Glucose
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0.0 0.5 1.0 1.5 2.0 2.5 3.00
5
10
15
20
25
30
35
300K
204K
103K
4K
Abs
orpt
ion
(a.u
.)
Frequency (THz)
L-Glucose - absorption peaks at low temperatureL-Glucose - absorption peaks at low temperature
many distinct absorption peaks at low temperaturemany distinct absorption peaks at low temperature
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We observed terahertz absorption as a We observed terahertz absorption as a result of intermolecular interactionresult of intermolecular interaction
&&
also dependence on structural change in a also dependence on structural change in a moleculemolecule
……… ……… in other molecules? in other molecules?
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Far-infrared absorption in Uric AcidFar-infrared absorption in Uric Acid
Uric AcidUric Acid
AllantoinAllantoin
structural dependence of absorptionstructural dependence of absorption
0.5 1.0 1.5 2.0 2.5 3.0
0
5
10
15
20
Abs
orpt
ion
(a.u
.)
Frequency (THz)
Uric Acid Allantoin
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0.0 0.5 1.0 1.5 2.0 2.5 3.0
0
5
10
15
20
25 300K
205K
98K
4K
Abso
rptio
n (
a.u
.)Frequency (THz)
0.0 0.5 1.0 1.5 2.0 2.5 3.0-5
0
5
10
15
20
25
30
35
40
300K
200K
100K
4k
Abs
orpt
ion
(a.u
.)
Frequency (THz)
Temperature dependenceTemperature dependence
stronger temperature dependence in allantoinstronger temperature dependence in allantoin
change in energy surfaces of molecules at low temperaturechange in energy surfaces of molecules at low temperature
AllantoinAllantoinUric AcidUric Acid
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Uric Acid - absorption line profileUric Acid - absorption line profile
change in position and width of peaks with change in position and width of peaks with temperature temperature
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ConclusionsConclusions
Demonstrated use of THz-TDS to study far-infrared Demonstrated use of THz-TDS to study far-infrared response of some isomeric and derived structures of response of some isomeric and derived structures of glucose and uric acidglucose and uric acid
Observed absorption due to collective Observed absorption due to collective intermolecular modesintermolecular modes
Strong temperature and structural dependence of Strong temperature and structural dependence of absorptionabsorption
Theoretical model analysis required to understand Theoretical model analysis required to understand the underlying dynamics the underlying dynamics
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AcknowledgementsAcknowledgements
EPSRCEPSRC
Royal Society Royal Society
Toshiba Research EuropeToshiba Research Europe
Association of Commonwealth UniversitiesAssociation of Commonwealth Universities
and thanks toand thanks to
Dr. M. B. JohnstonDr. M. B. Johnston
Dr. A. DowdDr. A. Dowd