Terahertz Absorption Terahertz Absorption Terahertz Absorption - - PowerPoint PPT Presentation

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Terahertz Absorption Terahertz Absorption Terahertz Absorption Terahertz Absorption Spectrum of Liquid Water Spectrum of Liquid Water Spectrum of Liquid Water Spectrum of Liquid Water

Indara Suarez Pasadena City College INSET Physics Mentor: Jing Xu Faculty Advisor: Prof. S. James Allen Funded by: NASA & Army Research Office (ARO)

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Motivation Motivation Motivation Motivation

Direct Absorption Measurement:

• How Much Does the Media Absorb per Thickness?
• Pnout ∝ exp (-tn α)

To Study the Physical Property of Liquid Water. Terahertz Absorption Spectrum of Water:

• Not Well Established
• Few Powerful Terahertz Sources
• Only Recent Development in Terahertz Optics

Approach Approach Approach Approach

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THz

t

F E L t = Sample Thickness 0.08 μm 0.16 µm 0.20 µm 0.24 µm

Pout ∝ e-t α

Experimental Experimental Experimental Experimental Apparatus Apparatus Apparatus Apparatus

Sample holder

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Preliminary Data Preliminary Data Preliminary Data Preliminary Data

signal Pout (V)

0.8 0.6 0.4 0.2 0.0 1000 800 600 400 200

Pout

n ∝ e-tnα

Time (µsec )

Absorption 5 10 15 20 1 2 3 4 5

Thickness (μm) Pout (V)

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Absorption Coefficient Absorption Coefficient Absorption Coefficient Absorption Coefficient

α = 35.09 μm-1 , R2 = 94.8% Ln(Poutn) ∝ - tnα

Thickness(μm)

y = -35.09x + 4.4237

• 10
• 8
• 6
• 4
• 2

2 4 6

• 0.05

0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

Ln(Pout

n)

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Future Work Future Work Future Work Future Work

• Create A Spectrum of the Absorption

Coefficients of Liquid Water in the Terahertz Range.

• Compare Data with Current Theories of

Absorption Spectrum of Liquid Water.

• Measure Terahertz Absorption Spectrum
• f Liquid Water with Biomaterial.

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Acknowledgements Acknowledgements Acknowledgements Acknowledgements

Professor Jim Allen

Jing Xu Professor Kevin Plaxco Mike Wrocklage

Liu-Yen Kramer Trevor Hirst Al Flinck Nick Arnold

Mike Northen Mel McLaurin Eric Hoffmann

National Science Foundation Army Research Office NASA

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Terahertz Circular Terahertz Circular Terahertz Circular Terahertz Circular Dichroism Dichroism Dichroism Dichroism Spectroscopy Spectroscopy Spectroscopy Spectroscopy

• Argument:

– Well structured, chiral, stereochemically-pure macromolecules are a universal sign of life.

• Approach:

– Making a spectrometer that will detect & fingerprint these macromolecules.

• Hopeful Conclusion:

– Finding life. (funded by NASA) – Finger-printing and identifying biological polymers. (funded by the ARO)

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Circular Dichroism:

Differential Measurement

Circularly Polarized Light

Rutgers-Newark Department of Chemistry

200 µm

0° 180° 90°

• 90°

Phase Difference Result

Eric Hoffmann